Transcript Pecan Fertility

Pecan Fertility and Orchard
Floor Management
Lenny Wells
UGA Extension Horticulture---Pecans
Leaf Sampling
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Sample trees between
July 7th and August 7th.
Use terminal shoots
exposed to the sun.
Collect leaflets from all
sides of the tree.
Avoid leaflets damaged
by insects and diseases.
Leaf Sampling
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Abnormal trees or trees not representative of the area
should be sampled and sent separately.
Sample trees of the predominant variety in a given block.
Immediately upon collection, wipe leaves (entire surface,
boh top and bottom) with a damp cellulose sponge or
cheese cloth to remove dust and spray residue.
Do not allow the leaves to come into contact with
rubber or galvanized containers.
If recent soil test data is not available, it would be
advisable to collect a soil sample and have it sent to the
Soil Testing Laboratory.
Soil Sampling
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Useful for pH and toxicities
Late Fall/Winter
Sample uniform area
1 pint/sample (15-20 cores) over large area
Sample to 8” depth
Nitrogen
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N absorption by roots is
driven by demand
Demand is regulated by
growth of leaves or fruit,
and production of
proteins.
Flowers may be aborted
if leaf N is deficient the
previous summer
Nitrogen
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Leaf Concentration: 2.5-3.3%
(Apply when less than 3)
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10 lbs N/100 lbs expected
crop
Shoot growth should be 8-12”
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Nitrogen
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In well managed, irrigated orchard soils, N can move
more readily and leach out of the effective root zone
before it is taken up by the tree.
Initial spring N used by developing foliage comes from
storage pools within the tree.
N demand will be greatest for “on” trees bearing a
heavy crop load, since expanding leaves, shoots, and
fruit create the greatest demand.
Nitrogen
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General Recommendation:
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75-100 lbs N applied mid-late April
Examine Crop in June/July
“On Year”---50 lbs around August 15
“Off Year”---0 lbs around August 15
OR
IF NO AUGUST APPLICATION
 75 lbs N in March/April (March after “on year”)
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25-75 lbs in late May/Early August
Most of the N taken up during the kernel-fill stage
will supply the N storage pool needed for early spring
growth.
Timing of fertilizer application for non-irrigated or
run-down orchards will be different
Nitrogen
Dry-Land /Neglected Orchards
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75 lbs N in March
25 lbs in late May
Young trees
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Year 1:
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Year 2: 1 cup in April, 1 in May, and 1 in June
Year 3-4: 2 cups in April, May, and June
Year 5-7: 4 cups in April, May, and June
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1 cup ammonium nitrate in June if growth is good
(2-4’ terminal growth)
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Year 1: 1 lb 10-10-10 fertilizer distributed in a 25 sq. ft. area around the
tree (apply in June if growth is good)
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After Year 1: 4 lbs of 10-10-10 fertilizer for each inch of trunk diameter
(measured one foot above soil surface). Do not place fertilizer within 12
inches of the trunk
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1 lb zinc sulfate per tree for the first three years following planting.
Nitrogen
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Fertilizing on a per tree basis
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Mature trees
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1 lb amm. Nitrate/inch of trunk diameter in late March before
bud break. Water in promptly
If lawn is concern, bore holes in ground and pour in, then water
area
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4 pounds of 10-10-10 for each inch of trunk diameter (measure 4
1/2 feet above soil level) up to 25 lbs/tree. This fertilizer should be
applied in late March before bud break. Zinc needs are best
determined by analysis of leaf samples taken in late July or early
August. (Max 2 lbs/tree)
Clover as a Source of Nitrogen
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Crimson – 100 lbs N/A
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White Clover--103 lbs N/A
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10 lbs/A seeding rate
1.00-1.50/lb
4 lbs/A seeding rate
2.00-2.50/lb
Use mixture
Allow clover to re-seed
Apply Poast in February
Potassium (K)
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K is transported to nuts at leaf’s expense
50-100 lbs K applied in February/March
During “on” year apply additional 30 lbs K in mid
August
1.25-2.5 ppm in leaf analysis
Manage N/K ratio to 2:1
Manage Mg---(No Dolomitic lime above .45% Mg)
Deficiency most common on Desirable and Schley
Basal Leaf Scorch
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Usually occurs in June/July
Results from imbalance between
N/K
More susceptible to winter
injury
Defoliation
Occurs on basal leaves of shoot
and moves upward
Scorched areas circular or
oblong/ dime size
Basal Leaf Scorch
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Maintain adequate K levels
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When K level is marginal or
deficient, N level should be
reduced until K is corrected
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Foliar K can help, but does
not replace soil applied
(Potassium Nitrate: 3
lbs/100 gallons)
Zinc
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Necessary for shoot
elongation, leaf
expansion, and yield
Apply when Zn in leaf is
below 50 ppm
2 lbs Zinc sulphate + 3
lbs Potassium
Nitrate/100 gallons
Begin 2 wks after
budbreak until shoot
elongation complete
Mouse Ear
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Nickel Deficiency
Zinc Management
Nickel lignosulfonate
Apply 1 pt/A in spring (April) while canopy
is developing (parachute stage);
2nd application: 1 pt/A 30-60 days after 1st
appl.
Third application of 1.5-2 pts/A in late
Sept.-early October before leaf fall to
prevent mouse ear in the spring flush.
Magnesium
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0.35-0.6% leaf
Deficiency occurs on acid soils
(pH <5.5)
High K or Ca
Use Dolomitic lime
Maintain pH of 6.0-6.5
OK to use calcitic lime when
Mg above 0.45%
If pH adequate, apply foliar
Magnesium Sulfate at 5
lbs/100 gallons (4” shoot
growth to July)
Chicken Litter
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Have sample analyzed
Typically 70 lbs N/ton; 35 lbs P;
40 lbs K;
0.6 Zn
Nutrients are organically bound
Organic matter adds tilth/waterholding capacity to soil
Apply between late February and
early June
Use BROILER litter and NOT
LAYER litter
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Ca/Mg
Water Split
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Occurs in August/September
on Certain Varieties (late
water stage/early shell
hardening)
Split occurs along ½ length
of fruit and may penetrate
shuck and shell
Rapid influx of water
Rain/Irrigation/
High humidity/Low solar
radiation
Water Split
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Occurs w/in 24 hrs of heavy influx of water to
soil
Most split occurs in upper 1/3 of canopy
Split occurs in pre-dawn hours
Fruit falls from tree within 7 days of splitting
Managing Water Split
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Maintain soil moisture 2-3 wks before shell
hardening (limited)
Fruit thinning
Avoid excessive N
Micronutrients?
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B, Ni, Cu
Orchard Floor Management
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Mature Trees
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Early Spring Pre-Emergence:
 Simazine—2-4 qts/A
Control of Annual Broadleaf weeds and some ann grasses
Use low rate on sandy soil
OR
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Surflan 2-4 qts/A + Simazine—2-4 qts/A
Broader Spectrum
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Karmex 2-4 LBS
Do Not use on sandy soil; Do not graze
Spring Post: (Can be mixed with pre-emerge applications)
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Gramoxone Max 1.75-2.7 pts or Boa 2-3 pts
20 GPA Volume improves control
Add 1 gal crop oil /100 gal spray mix
Broad Spectrum of Annual weeds when small and succulent
Do NOT contact foliage, green bark or allow animals to graze
OR
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Poast 16 oz/A-----Clover release
Orchard Floor Management
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Summer Burndown Herbicides:
(Do NOT contact foliage or green bark)
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Roundup (Glyphosate)
1-2 qts/A
OR
Roundup+Karmex 2-4 lbs
Use low rate on sandy soil
OR
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Gramoxone Max 1.75-2.7 pts
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Rely
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3-6 qts/A
Better on perennials
Orchard Floor Management
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Eliminate grass and weed competition under orchard trees
Non-Bearing Trees
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Pre-Emergence
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(after soil settles)
Surflan 2-4 qts/A
Surflan+Simazine (At least 2 yrs old)
Prowl 2.4-4.8 qts (after soil settles)
Solicam 2.5-5lbs. (after soil settles)
Post-Emergence
Roundup (Glyphosate)
1-2 qts/A
 Rely (Glufosinate) 3 -6 qts/A
 Poast 16 oz/A
OR
Fusilade 16 oz/A
1 qt crop oil
low spray volume (10 GPA) increases activity
(no broadleaf activity)
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Do NOT contact foliage or green bark
Basic Needs of the Pecan Crop
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Light
Water
Leaf Retention
Management of Crop Load
Pollination
Pecan Irrigation
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71,031 Irrigated Pecan Acres in GA
(~50% of crop)
based on UGA Farm Gate & Irrigation Surveys
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Average Amount Applied/Year = 15.5”
Average Cost/Year = $64.50/A
18,254 Acres irrigated by solid-set
52,777 Acres irrigated by drip
Irrigation Schedule for Pecans
MONTH
SPRINKLER
DRIP
Inches/A
% cycle
April
0.5”
60
May
0.75”
70
June
1”
80
July
1.25”
90
August
1.5”
100
September
1.5”
100
October
1”
90
November
0.5”
60
Pollination
Pistil Receptivity
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Desirable (I) – April 23-May 4
Cape Fear (I) – April 22-May 4
Stuart (II) -- April 22-April 29
Sumner (II) -- April 22-April 28
Elliott (II) – April 19-April 30
Schley (II) – April 19-April 27
Pollen Shed
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Desirable (I) – April 23-April 28
Cape Fear (I) – April 23- April 30
Stuart (II) – April 28-May 7
Sumner (II) – May 1-May 7
Elliott (II) – April 27-May 3
Schley (II) – April 23-May 3