Slide 1

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 2

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 3

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 4

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 5

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 6

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 7

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 8

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 9

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 10

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 11

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 12

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 13

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 14

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 15

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 16

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 17

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 18

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 19

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 20

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 21

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 22

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 23

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 24

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 25

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 26

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 27

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 28

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 29

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 30

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 31

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 32

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 33

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 34

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 35

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 36

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 37

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 38

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 39

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 40

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 41

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 42

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 43

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 44

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 45

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 46

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 47

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 48

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 49

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 50

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 51

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 52

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 53

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 54

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 55

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 56

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 57

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 58

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 59

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks


Slide 60

Lecture 11

RHUBARB

Botanical Description
Botanical Name :

Rhubarb rhaponticum

Family

:

Polygonaceace

Ch. Number

:

2n=22

Origin

:

Southern Siberia and China

AREA AND PRODUCTION
• Rhubarb is a native of the cooler areas of Asia,
probably Siberia but it is grown in Europe and
England and used as a tilling for tarts and pie.

• A Maine grower who obtained seeds or rootstalks
from Europe Jrew rhubarb in the United States as
early as 1800.
• It is commercially cultivated in the Massachusetts.

Varieties:
• Rhubarb can be grown as an outdoor plant
and as a forcing plant.
• Cultivars of rhubarb may also be chosen
according to the cooler to their petioles.

For outdoor production:
• The cultivar MacDonald has large red stalks.

• It is vigorous and upright growing.
• Valentine is another red stalked cultivar that
is popular for growing in home gardens.

For forcing :

Timperley, Early Victoria,
Crimson Red and Sutton are
used.

Green-stalked cultivar : Victoria, is a heavy
producer and excellent for
commercial purposes.
Pink- stalked cultivar : Sutton

Land Requirement
Before planting this polygonaceae crop, consider the

following important factors:
 No polygoneous crop (Sorrel) or related weed (dock
plants) has been present in the Held for at least 2
years,4 years preferable.
 Polygoneus crop like Buckwheat.
 Also, polygoneous crops waste should not have been
dumped on these fields.

Soil
• It should be well drained.

• Rhubarb prefers deep, fertile loams and
does best in slightly to moderately acid soil.

CLIMATE
• Rhubarb is a cool-season, herbaceous, perennial

crop .
• It grows best when mean summer temperatures are

below 75° F or when winter mean temperatures are
below 40° F.
• Grown in the northern tier of the United States in a
region extending from Maine south to Illinois and
west to Washington.

 The plant requires temperatures below 50° F to
break dormancy.
 Rhubarb is not easily grown in the southern United
States because high temperatures disrupt growth.

 Cultivars that exhibit good pink or red petiole
colour during the cool season usually becomes very
green when temperatures remain above 85° F.
 The vegetative parts of the plant are killed at 26° or
27° F.

PLANTING
 Rhubarb is usually propagated by dividing the

crowns formed during the previous season.
 Crowns are divided in late fall or early spring.
 Plants must be divided and reset every 4 years to
keep the bed in vigorous condition.
 Plants not divided may become large and stalks may

become more numerous than desired.
 Seed stalks should be removed as they appear.

 Typical spacing for commercial rhubarb planting
is rows 4 ft apart with plants 4 ft apart in row.
 Trenches are dug prior to planting, generally 6
inch deep.
 Crown pieces are placed 2 inches below the
surface of the soil in the trench.

 Soil is pulled over the soil and firmed.
 Good drainage is essential for growing rhubarb.

Irrigation
• The rhubarb plant responds well to moisture,
although reliable yields can be obtained with
minimal watering.
• Irrigate prior to harvest to increase crop yield
and delay irrigation after harvest until plant
injuries have healed.

Mulching
 Straw may be applied in late fall or during
the winter as a mulch to keep down weeds
and ensure a cleaner harvest environment

from soil.
 Straw mulch may also be used to surface

burn a held to control diseases and insects
(especially potato stem borer).

Culture and Care
The first growing season –

 Plant only in fields that are as clean as possible from
perennial weeds.
 Cultivation should be shallow and throughout the
growing season.
 Some hand hoeing will be required: contact herbicides

may be sprayed between the rows with the crop shielded.
 Flower stalks should be cut off as soon as they appear.

 One or two side dressings of nitrogen may be necessary.
 No crop should be harvested the first season.
 In the fall, well rotted manure and/or straw should be
applied to the soil surface.

Following years –
 Cultivate occasionally to keep weeds in check but be
careful not to cultivate too deep or close to the crown
and fleshy roots.

 Rhubarb grown for seed production is

planted in a field for 2 years in which the
stalks and petioles are not harvested.

 After 2 years of growth the roots are ready to
be dug for seed production.

 It should be exposed to the low temperature
to break the dormancy.

 The crown and roots used for seed production
must be dug before the soil freezes, taken
storage, and held where dehydration and water
loss are at a minimum until it used for planting.
 When ready for planting, the crowns are packed
together on 4-5 ft wide beds with soil and water

added to initiate growth, and then placed in the
dark.

MANURES AND FERTILIZER:
 Rhubarb grows best in soils with a pH in the range of 6 to

6.8.
 The crop has a high demand for calcium and magnesium.
 Rhubarb is a heavy feeder, therefore will do best on sandy
loam to loam soil with a good organic matter level.
 To achieve early field production, plantings need to be made

on light soils with a southerly exposure.
 The site should also be sheltered.

 Rhubarb can remove upwards of 220 kg/ha of
nitrogen from the soil.
 The nitrogen should be replaced in 2-3 applications
with the first application at bud break.
 The remaining applications should be made after
harvest.

 Try to avoid putting nitrogen fertilizer to close to the
roots as it can burn the small feeder roots.

 All additions of lime and fertilizer or manures should be
based on recommendations from a soil test.

 When test results are not available the general
requirements from Tables 1-4 of the soil and water
management section of this guide may be followed.

 Phosporus is not very mobile so select a planting site that
is high in phosphorus.
 If additional phosphorus is required it can broadcasted

with nitrogen and potassium early in the spring and
mixed into the soil with a light cultivation between the
rows.

• Rhubarb grows well in a highly fertile soil

high in organic matter and well drained.
• A green manure crop is desirable the year

before planting.
• Also in the fall 45 tonnes of manure per

hectare may be added. (An annual fall
application of manure would be beneficial).

Lime
• Is applied to maintain the soil pH in the range
6.0 to 6.8 (rhubarb will tolerate soil acidity as
low as 5.0 but yields and fertilizer efficiency
will suffer).
• As with all crops the calcium level should be
3000 kg/ha to be in line with current soil
testing methods.

Nitrogen
 Rhubarb has a high requirement for nitrogen.

 Apply only as necessary in the establishment year.
 Otherwise apply nitrogen at bud break along with the
phosphorus and potash requirements.
 Apply one or two side dressing of nitrogen after harvest
( delay until good regrowth has began) or on crop to be
used for forcing.
 Application of manure will supply part of the nitrogen
requirement of this crop.

Phosphorus
 Is the most important in the establishment year.

 Field selected for rhubarb should be high in
phosphorus.
Potash
 Is the only added if soil level are not adequate but

is usually required if high yields are being taken
and manure is not being used.

Magnesium & /or Sulfur
• May be needed on sandy soils low in organic matter.
• Foliar sprays of epsom salts or the use of gypsum and
dolomitic limestone may be considered.

Micronutrients
• Boron may be necessary for the health of buds and
roots.
• It may be applied in the fertililzer , as soil drenches
and / or foliar sprays.

 Apply 1 to 2 kg per hectare per year of actual boron.
 Be careful not to burn foliage or roots in the establishment
year.
Application method –
 Broadcast N, P & K in the spring and apply manure in the
fall.
 Sidedress or broadcast nitrogen or apply it through an
irrigation system.
 Cultivation between the rows will mix some of the broadcast
fertilizer into the soil and control some weeds.

Use of Growth Regulators
• Gibberellic acid is useful in rhubarb forcing
to assist in breaking dormancy to permit early
production.
• This may allow time to force two crops in the
house.
• Gibberellic acid also tends to increase yields.

Roguing:

 Timely and regular interval rouging for off
type, diseased plants affected by crown rot.

 Viral diseases infected plants are important
also, weed like dock plant removed at

regular interval.

Seed Production

Method of Seed Production
• There are three major methods used to produce
seeds in Brussels sprout.
• seed to seed method
• root to seed method

• Out of these three methods, root to seed method is
commercially used for production of seeds.

Seed Certification Standards:
I. Field Inspection:

A. Mother Knots/Crowns production stage:
 Minimum two inspections arc required to produce

quality seeds.
The first inspection is done after 20-30 days of the
sowing in order to determine isolation, volunteer
plants, out crosses, off types and other relevant
factors.

• The second inspection is done after the
mother roots have been lifted to verify the
true characteristics of roots.

B. Seed production stage:
• A minimum of one inspection is done

during flowering to check isolation, off
types and other relevant factors.

II. Field Standards:
A. General Requirement:

Isolation:
Contaminants

Minimum distance(meters)
Mother root production
stage

Seed production stage

FS

CS

FS

CS

Fields of the other
varieties of the same
species

5

5

1600

1000

Fields with same variety
not confirming to varietals
purity requirements

5

5

1600

1000

B. Specific requirement:
Factors

Maximum permitted (per cent)

FS

CS

Off type

0.10

0.20

Plant affected by
seed born diseases

0.10

0.50

III.SEED STANDARDS
Factors

FS

CS

Pure seed (min.)

98%

98%

Inert matter (max)

2%

2%

Other crop seeds (max)

5/kg

10/kg

Weed seeds (max)

10/kg

20/kg

Germination (min)

60%

60%

Moisture (max)

7-9%

7-9%

For vapour proof
container (max)

5%

5%

Weed Management
• Control weeds well before planting.
• Start cultivation early in the spring.
• Cultivation should be shallow to avoid injury to
roots and can continue as late in the season as
possible without damaging the plants.

• Contact herbicides are registered for use but the
crop must be well shielded.

• Various types of mulch may be used

between the plants and in the rows
(most commonly straw).
• Grass weeds can be controlled with
glyphosate

or

round-up

Grammaxone or Paraquat.

or

with

Insect Management
Potato stem borer
Characteristics
• The potato stem borer is a caterpillar, which when fully

grown is about 3.5 in length and pinkish-white in colour.
• The first stages of the insect attack only weeds, couch grass
in particular.

• Later they move into plants with thicker stems, such as
rhubarb.

 They may move from stem to stem, boring into the
centre of the stalk.
 The adult moths lay their eggs on the stem of
grasses in August.
 The eggs do not hatch until the following spring.
 Damage can be expected in June and early July.
 Serious infestation can lead to an unmarketable
crop.

Control:
• This pest is not a problem when couch grass and

other weeds are controlled in and around
the rhubarb plantation.

• Weeds should be controlled to make the field less
attractive for egg laying by the adult moth.
• Early spring burning of affected fields or field
margins will effectively control this pest.

Tarnished plant bug
Characteristics:
 Adult tarnished plant bugs are light brown to
reddish brown in colour and about 5-6 mm in
length.
 They occur throughout the season.
 They are very active and quick moving.
 They can damage rhubarb by feeding on young
leaves.

• They pierce the stalk with their mouthparts and
cause wilting and distortion of the leaves.
• Tarnished plant bugs are mainly a pest of new
plantings.
Control
• Keep plantings and adjacent areas weed free.
• Avoid planting adjacent to legumes.

Slugs
Characteristics:

• Slugs may be a problem in plantings with
heavy soils, poor drainage and in weedy

situations.
• Slugs fed at night, by rasping the surface of

stems, leaving unsightly scars, which reduce
the sale ability of the stem.

Prevention:
• Provide good soil drainage.
• Keep weeds under control.

• Remove leaves and trash from the field when
harvesting.

• Do not use manure and/or mulches in areas
of field prone to slug damage.

Other Insect Pests

• Black bean aphid (Aphis fahae) : caused
problems on occasion.

• Large infestations may cause curling or
wilting of leaves.

• There is also potential for the spread of virus
by aphids.

• Flea beetles - can cause damage to new plantings
by their feeding activity on the leaves.
• They are especially active during periods of hot
dry weather.
Control:
• Provide good weed control.
• There are no products registered for either of these
pests.

Diseases Management:
Leaf Spots and Ascochyta leaf spot

• These fungi cause circular, or angular spots,
variable in size having beige centers surrounded by

a red zone.
• When affected tissue dies, it may drop out. leaving
large ragged holes in the foliage.
• Fungi overwinter in infected plant debris and in
infected propagation stock.

Control:

• Remove and destroy leaves following the
first heavy frost.

• During harvest, remove stems with spotted
leaves first. Apply fungicide used for

Botrytis control.

Botrytis Rot (fungus)
• May cause a leaf, stem and crown rot of forced

rhubarb.
• Disease intensifies where there is poor air circulation
and high humidity.
• Control:
• Practice strict sanitation.
• Apply recommended fungicide at first sign of disease
and at 7 day intervals.

Root and Crown rots (fungi and bacteria)

Characteristics:
• Plants become unthrifty.

• Leaves may turn yellow to red and collapse.
• The Crowns, Sectioned, exhibit a brown-

black lesions present.

Virus
Characteristics:

• Several viruses are known to occur in rhubarb.
• Reports from British Columbia and the U.K.

indicate that turnip mosaic , arabis mosaic.
and cherry leaf roll virus are the most common.
• These viruses have wide host ranges and cause
mottling and ring spotting of leaves.

• They may be introduced in infected

planting stock.
Control:
• Obtain and plant healthy nursery stock.
• Avoid planting virus free crowns near
virus contaminated crowns

Harvesting and Yield
The best time to harvest a seed crop is at stage when
the highest yield of best quality seeds will be obtained.
• Seed crops are harvested when plant start drying in the
field and seed are usually dried on the plant before

harvesting.
• Plants are manually harvested cutting with ground level
or whole plant pulls up and threshed to remove the

seeds.
• Red varieties tend to yield about half of the green
varieties

• Field yields can vary depending on the age and
vigor of the stand.

• Yields can range between 15.000 and 40,000 kg per
ha (13.500 and 36.000 lbs/acre) in a single cutting
harvest season.
• Harvest begins in late May or early June depending
on location and can last for 8 to 10 weeks.
• Rhubarb is harvested by hand.
• The stalks are pulled rather than cut

 The leaves are removed in the field and only the stalks
are marketed.

 Harvesting the year following planting is possible but
has been found to reduce productivity in the long run.
 Second year harvests are preferred.

 A healthy stand should remain productive for 5- 10
years.
 Seed crop start to harvesting from three years age
onwards.
 Seed yield varies between 250-400 kg/ha.

Seed Package
Well dried Seeds are packed in the plastic bags,

tin cans, cloth bags etc. packing or bagging consists
of following operations.

Filling of seed bags to an exact weight.
Placing leaflets in the seed bags regarding
improved cultivation practices.
Attaching labels, certification tags on the seed bags
and sewing of the bags.

Seed Storage
• Seed can be store at 0 2°C and a relative
humidity of 95 to 100%.
• Under these conditions, seed can be stored
1-2 years.
• Good air circulation is also essential.

Thanks