Transcript LAWN PROBLEMS IN FESCUE LAWNS

LAWN PROBLEMS IN FESCUE
LAWNS
Prepared by
John Johnson
Bridgett Hand
Camron Jasper
Presented by
John Johnson
Lawn and Garden Manager
Ace Peninsula Hardware
THE BIGGEST PROBLEM WITH FESCUE LAWNS IS OWNER OPERATION OF
LAWNMOWERS. EITHER THE BLADE IS TOO DULL OR THE GRASS IS CUT TOO
SHORT. DULL BLADES TEAR THE GRASS, RATHER THEN CUT IT, LEAVING RAGGED
EDGES THAT INVITE ALL KINDS OF DESEASES AND FUNGUI
BLADE CONDITION
Toro Lawn Mower
Sharp blades help your mower deliver the
best quality of cut...but they also contribute
to the ongoing vitality of any lawn. That’s
because a dull blade...
“Mowing with a dull blade shreds the ends of grass leaves,
causing browning from tip dieback and a heightened risk
of disease. The cleaner the cut, the less the injury.”
Dr. Van Cline
Toro Agronomist
Manager of turf research,
Center for Advanced Turf Technology
Dull Blades Damage Turf!
• Shreds plant tips, leaving them vulnerable
to attack by fungal disease and increased
desiccation
• Causes the plants to die back, creating an
unsightly brown appearance to the lawn
• Slows the growth of grass blades
Mowing Height and Frequency
A neatly trimmed lawn is generally considered to be more attractive than one that is
unkempt and shaggy. By mowing frequently and maintaining a uniform turf surface, a neat
appearance can be achieved, even at taller heights. Unfortunately, however, a common
perception is that a short turf is superior in appearance to tall turf. In reality, turf that is
uniform appears neater than uneven turf, regardless of height. Proper height and
frequency are the two most important aspects of a turf mowing program.
Mowing height Mowing turf at the appropriate height is important to turf health and
appearance. Turf cut too short usually has a shallow root system, lacks density, and often
requires pesticide applications to stave off weed and pest infestations that commonly
occur in stressed lawns. Conversely, tall turf is often considered to be unattractive because
of wide leaf blades, low density, and a clumpy, unkempt appearance. In addition, tall turf
may not be satisfactory for some sports applications.
Mow turfgrasses according to the heights presented in Table 1. Note that a range is listed
for each species. When healthy and actively growing, turf can be mowed at the lower
heights; raise mowing heights within the desired range during warm-hot periods or when
turf is stressed due to drought, disease, shade, insects, or traffic. The heights listed in this
table provide a balance between turf appearance and health.
Mowing frequency Turf should be mowed as necessary, not according to a preset
schedule. Turfgrasses grow at different rates depending on weather, management, and
species. A basic recommendation is to remove no more than one-third of the grass blade
at any one mowing. For example, Kentucky bluegrass being maintained at a two-inch
height should be mowed when it reaches three inches. This "one-third rule" will help
maintain maximum turf root growth. Removing more than one-third of the grass blades
may cause root growth to cease while the leaves and shoots are regrowing. This practice
can be especially destructive if practiced continuously over a period of successive
mowings. Roots may not have a chance to fully develop and the plants will thus be more
susceptible to environmental and management stresses. Maintenance of healthy, growing
turf root systems should be a primary consideration of any turf management program.
Turf Species
Fescues
creeping bent grass
Zoysia grass
Mowing Height (in inches
2 to 3
1/4 to 3/4
1 to 1.5
Insects
Bill Bugs
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Billbugs
(crown & thatch inhabitant)
Adult billbugs are about 1/5" — 3/4" long. They are beetles with long snouts,
or bills, that carry to the tip a pair of strong jaws or mandibles with which the
beetles chew their food. Clay yellow to reddish brown to jet black in color.
The beetles burrow in the grass stems near the surface of the soil and also
feed on the leaves. Several species of billbugs damage lawns. The bluegrass
billbug is a bluegrass pest. The Hunting Billbug causes damage to Zoysia
grass.
Bill Bugs are found in two forms: adult and larvae (infant). The adult Bill Bugs
look like a small beetle and are distinguishable by the long elephant-like bill
that protrudes from their head. Hence the name. The adult Bill Bug feeds on
grass stems above the surface. The younger Bill Bugs, or larvae, look like Cshaped, legless, wet pieces of white-rice and feed on grass roots.
Bill bugs cause the most damage when they are larvae, and can
spread and destroy large sections of grass if not contained or killed.
Common signs of Bill Bug problems are dead spots on your lawn that
don't recover from watering. Since the larvae feeds on the roots, you
can also tell by pulling-up on the dead grass and see if it comes up
easily from the roots. If so, it could be Bill Bugs.
Chinch Bugs
Adapted from the University of
Massachusetts
Description:
chinch bugs are complex of three different species within the Lygaeidae family. They have
piercing-sucking mouthparts and they feed on the sap of grass plants. They reside in the thatch
area of the turf grass stand and prefer to feed on the lower leaf sheath and crown area of the
plant. The chinch bug can be a major insect pest on home lawns throughout the country. The
hairy chinch bug (Blissus hirtus) is the most common species in the Northeast. The hairy chinch
bug prefers bent grasses, but will attack many other lawn grasses as well. The adult chinch bugs
are about 3 to 5 mm (1/8 to 1/5 inch) in length and black with white markings on the wings. The
wings rest flat over the back of the insect and there is a black spot between the wings. Adults
may be long-winged or short-winged. There are five nymphal instars of chinch bus ranging in size
from 1 to 3 mm (1/32 to 1/5 inch). The first two nymphal instars are red, with a white band
across their abdomen, while the third and fourth instars are orange with wing pads just
beginning to appear. The fifth instar is black with wing pads easily visible.
Damage:
The chinch bug inserts its straw-like mouthparts into the plant tissue and sucks out the plant
juices while injecting chemicals into the plant which clog the vascular system. The area around
the feeding puncture usually turns yellow. Damaged areas first appear as small, irregular
patches which enlarge as the insects spread. Chinch bugs are most damaging in open, sunny
areas.
Life Cycle:
Chinch bugs spend the winter as adults in partially protected areas (under shrubs or around
foundations of houses). As the weather warms in the spring, adults move into open areas,
where females begin laying eggs. Fifteen to 20 eggs per day are deposited for two to three
weeks. The eggs hatch in one to two weeks, and the nymphs begin to suck the juices from host
plants. It takes 30-90 days to reach adulthood. There are two generations per year, with a partial
third generation in unusually warm summers. There is considerable overlap of generations, and
all stages can be found during the summer.
Detection:
Examine the grass in the marginal areas of injured patches, not in the clearly dead grass.
Spread the grass gently with your fingers and look in the thatch, near the soil surface.
Chinch bugs are usually very active in the summer, so you will be able to see them
scurrying around, especially on warm summer days. An alternative method of detecting
chinch bugs is to remove both ends of a large tin can, such as a coffee can. Soften the soil a
little with water, and insert one end of the can into the ground at least 5 to 8 cm (2-3
inches) deep, leaving at least 10 cm (4 inches) of the can above the ground. Fill the can
with water and wait about five minutes. If chinch bugs are present, they will float to the
surface of the water, where you can count them.
Control:
In many instances, chemical control of chinch bugs is not necessary. Studies in Michigan
have demonstrated that lawns which receive adequate amounts of water throughout the
summer (preferably weekly deep watering) are able to tolerate relatively high populations
of chinch bugs without sustaining damage. In addition, many lawns have natural
populations of predators, such as ground beetles or "big-eyed bugs," which can keep
chinch bug populations from getting out of hand.
Insecticide applications sometimes have very adverse effects on these predators,
causing the chinch bug populations to develop more rapidly in subsequent years. Plant
resistance has also been reported for a number of turf grass species and cultivars.
Research has demonstrated strong resistance of endophyte-enhanced turf grasses to
the hairy chinch bug.
Turf grass managers usually control chinch bug populations after major damage has
occurred. To avoid this problem in areas with habitual problems, an April to mid-May
insecticide application will control the overwintering females and subsequent
generations during the summer. Reinfestation may occur from adjacent areas, but this
process is slow and may require an additional year or more. This adult treatment must
be made before egg laying occurs. As with any pesticide application, be sure to read the
label and apply the material at the specified rate. Avoid mowing the area for two or three
days afterward.
Adapted from the University of Massachusetts Extension, 1999
Grubs
University of Illinois
White Grubs in Lawns
Concerns are often raised about white grubs in lawns and ways to manage them. Late
summer into early fall is the time white grub problems are most likely to show in lawns
here in northern Illinois. While a relatively small percentage of lawns will actually get
white grubs in a given year, this insect can cause serious damage when a significant
population occurs on a lawn or other turf area.
Since white grubs are often asked about, this month’s Lawn FAQ features white grubs in
lawns and summarizes the most common questions regarding this pest of home lawns.
How do I know if I have grubs in my lawn?
Why does my lawn have grubs but not my neighbor?
How can I predict if my lawn will have grub damage this year?
Can I prevent grub damage?
What about using organic controls for grub control?
What should be done after grub damage has occurred?
How do I know if I have grubs in my lawn?
White grubs feed on the roots of grasses, so lawns will show wilting and browning of
irregular shaped areas. Certainly there could be many reasons for lawns browning,
especially in late summer when most grub damage occurs. Always check the root zone of
affected areas for the white, c-shaped grubs. Carefully pull back the sod in suspect areas,
in particular the marginal areas where brown grass meets green grass, and look for the
grubs. Usually a population of about 10 or more grubs per square foot will lead to
browning of the lawn.
Peeling back a damaged lawn area has revealed
these white grubs in the soil as the cause.
Keep in mind other factors that can lead to poor rooting and are mistaken for grubs. For
example, lawns in shade areas often have weak roots and are pulled-up easily. Grubs do
not typically appear in shade lawns. Also, many lawns were easily pulled up this spring and
grubs were blamed. Once grass dies, regardless of the cause, roots will rot away and the
grass is very easy to tear out. So trying to diagnose grub damage from the previous season
as the cause of a dead lawn area in spring is very difficult to do, even if limited roots are
found in an area of dead grass.
Raccoons and skunks have damaged this lawn
area looking for grubs.
Another sign of grubs is damage from skunks and raccoons digging up lawns in
search of grubs to eat. This usually happens at night. Moles may or may not be
feeding on grubs so are not a reliable indicator of grub problems.
Why does my lawn have grubs but not my neighbor?
Keep in mind the adult stage of the grub life cycle is a beetle, which can fly. Random
chance is part of the answer. But adult beetles usually lay eggs in full-sun lawn areas
with adequate soil moisture. The masked chafer (annual white grub) and Japanese
beetle lay eggs in July. So if the weather has been dry but your lawn is watered and
surrounded by dry lawns, it is a prime target for egg laying
How can I predict if my lawn will have grub damage this year?
It is difficult, as insects can go in cycles and many factors influence the chances of
grubs appearing in your lawn. Lots of adult beetles on the lawn in July is one
indication. Masked chafers, the adult of the annual white grub, are tan beetles active
shortly after sundown. Japanese beetles fly during the day and feed heavily on many
ornamentals. Noting these adults and then having irrigated lawns surrounded by drier
turf increases the chances of grub damage to your lawn. Watch lawns closely starting
about mid-August and continuing into September for wilting and browning areas, and
then check the root zone for grubs.
The masked chafer is the adult beetle which lays
eggs becoming the annual white grub in lawns
Japanese beetles, which have been increasing in
Illinois, feed on many plants as adults and lay eggs in
lawn areas which may become a grub problem later
in the season
Can I prevent grub damage?
There are some options to consider. One option is allowing the lawn to go into dormancy
if conditions dry due to lack of rainfall in July, reducing the odds of grub damage since
the adult beetles look for green lawns with good soil moisture for egg laying. The
downside is the lawn will be brown and dormant. Also, this may not be reliable if rainfall
keeps grasses green throughout July, although if all lawns are green, the chances of
significant grub damage on any one lawn are low since the adult beetles tend to disperse
and lay eggs over a much broader area under this scenario.
Another option is to closely monitor the lawn as we advance into late summer and be
ready to act if grubs start to appear. Watch for grass areas going off-color and just
starting to brown, in particular those areas that have been irrigated. Check the root zone
for small white grubs. Insecticides such as diazinon or trichlorfon (Dylox) can be applied
when grubs are first noticed to prevent large-scale damage.
Other insecticides such as imidacloprid (Merit) or halofenozide (GrubEx) can be applied
prior to noting damage, such as in late July to lawns likely to show damage (adult beetles
present, irrigating lawn). All of these insecticides should be watered into the soil for best
results. Lawns should also be watered prior to application.
With all insecticides, read and follow label directions. To confirm what a product contains
as active ingredient, check the active ingredient section on the front of the label
What about using organic controls for grub control?
Heterorhabditis bacteriophora nematodes have shown good results for white grub control.
Nematodes are very small unsegmented worms. This particular species will search out
white grubs and after entering the grub, release bacteria that kills the grub. This product is
available in mail order catalogs, often sold as Hb nematodes. This product should be
applied late in the day to lawns with adequate soil moisture and then watered in
immediately.
What should be done after grub damage has occurred?
If significant grub damage has occurred, the lawn will need some renovation work in early
fall. Rake away dead debris. Water the lawn area, as some of the grass with damaged roots
may recover, especially if the weather cools down. Bare or thin areas may need some
reseeding. Labor Day is a good target date for lawn renovation work in northern Illinois.
Fungi
Brown Patch
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Brown Patch / Large Brown Patch
Rhizoctania solani
Brown Patch, which is also known as large patch, is a common soil-borne
fungus that attacks a variety of plants including almost all turf grasses. It is most
common to Bermuda, Kentucky Bluegrass, Centipede Grass, Bent grass, St.
Augustine, and ryegrasses in regions with high humidity and/or shade. Tall
fescue is also prone to the development of Brown Patch.
Brown patch commonly starts as a small spot that can quickly enlarge. As the
disease progresses and becomes larger, it will take on a circular, or sometimes
a horseshoe shape, that could be several feet across or larger. As the infected
area becomes larger, the initially infected area begins to recover, creating a
brown circular pattern in the lawn.
Conditions most favorable for brown patch development include the presence
of active fungi responsible for the disease coinciding with a seasonal time when
the susceptible grass is aggressively growing combined with a climate where
daytime temperatures range between 75 — 85 degrees and night-time
temperatures hover above 65. Poor surface and subsurface drainage combined
with excessive fertilization (nitrogen) are both factors that greatly increase the
intensity of this disease.
Brown Patch Symptoms
On warm season turf grasses, the disease is characterized by at least two different
types of symptoms. The most common is a circular pattern of brown grass with a
yellowish ring (smoke ring) of wilted grass on the perimeter of the diseased area. The
leaves can be easily pulled from the stolons with the smoke ring because the fungus
destroys the tissue at the base of the leaf. Symptoms first appear as small circular
patches of water-soaked, dark grass that soon wilt and turn light brown. Stolons often
remain green as the disease develops, the circular patches enlarge, smoke-rings
become apparent and new green leaves may emerge in the center of the circular areas.
Control
When environmental conditions are favorable, brown patch is likely to develop on
susceptible turf grasses. The severity of the disease can be somewhat controlled by
following a strict fertilization schedule that only apply the proper amount of nitrogen and
trace elements during the ideal times; by watering early in the morning to remove dew
and all the grass to dry quickly; mow grass a little taller with a sharp mower blade, and
when possible , by bagging the lawn
clippings during likely periods of disease activity. Fungicide applications are most
effective when used as a preventative before the disease has become established in the
lawn.
Since brown patch typically only kills the leaf, lawns attacked by brown patch will usually
return when conditions improve as long as secondary problems do not take advantage
of the turf grass in its weakened state.
Prevention
The best prevention for brown patch is to aerate often, reduce shade to effected areas,
and follow a fertilization schedule to help prevent fertilization with excess amounts of
nitrogen. Avoid irrigating late in the day. Do not over-fertilize.
Treatment
The most common fungicides used on Brown Patch are: benomyl, and chlorothalonil.
The brown patch fungus will survive in thatch and turf debris between periods of activity.
Chemical controls are available, but should only be applied by licensed applicators.
Contact your local lawn care provider for additional information.
Dollar Spot
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Dollar spot is rare on sports turf and professional landscapes. Outbreaks may occur in residential
lawn turf and can reduce the lawn’s aesthetic quality and contribute to an overall decline in turf
vigor.
Dollar spot is one of the most readily identifiable diseases on golf course turf. Characteristic
symptoms on creeping bent grass include small (up to 1 inch in diameter), round, tan-colored
spots (Figure 1). The spots often occur in clusters and can cause considerable damage to playing
surfaces if not appropriately managed (Figure 2). Figure 3 shows a research site where various
treatments were applied to control
dollar spot (green rectangles). The brown turf surrounding the treated areas shows severe dollar
spot damage.
In the early morning hours after a long dew period, the dollar spot pathogen will produce an
abundance of mycelia on affected plant parts (Figures 4, 5). Characteristic symptoms on
individual plants include distinct lesions on leaf blades (Figure 6) with straw-colored centers and
red-brown margins. Leaf spot symptoms are more readily observed on taller mown turf species
such as Kentucky bluegrass and perennial ryegrass.
The dollar spot pathogen survives in the turf environment as mycelium in infested turf debris.
The pathogen becomes active with rising temperatures in the spring. Mycelial growth and
infection occur during extended
dew periods (longer than 8 hours) over a broad range of temperatures (55˚-80˚F). On golf
course fairways
and putting greens, dollar spot severity is increased significantly in nitrogen-deficient turf.
On residential turf, dollar spot usually accompanies the normal depletion of nitrogen
nutrition in late spring or early Summer.
The pathogen produces no spores; spread occurs through radial growth from individual
infection centers and by the movement of infected and infested leaf blades, usually
through turf maintenance operations such as mowing and core aeration. Dollar spot is
caused by a fungal pathogen (Sclerotinia homoeocarpa) that blights leaf tissues but does
not affect turf grass roots or crowns. The disease is a common concern on golf course
turf, especially creeping bent grass and annual bluegrass greens, tees, and fairways,
where it can result in poor turf quality and appearance.
Leaf Spot
North Carolina State University
SYMPTOMS
Leaf spot and melting out are common diseases in bluegrasses and bermuda grasses
caused by species of Drechslera and Bipolaris (formerly known as Helminthosporium).
In the bluegrasses, this disease is most active during warm and humid weather, but in
bermudagrasses, most damage occurs during cool and wet periods in the fall and
spring. Leaf spot symptoms are expressed in the early stages of the disease, but if left
uncontrolled, the pathogen may progress into the basal portions of the plant to cause
“melting out”. Leaf spot symptoms initially appear as small, brown or black spots or
flecks on the leaves or sheaths. As the lesions expand, the center of the lesions
becomes tan with a dark brown or black border. The lesions may also be surrounded
by a yellow halo. As the lesions expand, they coalesce and cause dieback of entire
leaves or plants. Melting out symptoms appear as a reddish brown rotting of the
sheaths, crowns, rhizomes, or stolons which initially leads to wilting, yellowing, or
death of the foliage. Symptoms of leaf spot and melting out appear in irregular
patterns, although localized “hot spots” may be more severely damaged than others.
FACTORS AFFECTING DISEASE DEVELOPMENT
Leaf spot/melting out is one of several Helminthosporium diseases which survive in
thatch during periods that are unfavorable for disease development. These fungi are
most active during periods of cool (60 to 65 degrees F) and wet weather, but some are
able to cause disease whenever temperatures are above freezing.
Leaf spot/melting out is most severe on turf that is growing slowly due to adverse
weather conditions or improper management practices. Shaded areas with little or no
air movement result in weak turf and extended periods of leaf wetness that favor
disease development. Deficient or excessive nitrogen, excessive thatch, extended
periods of leaf wetness, drought stress, and low mowing heights are factors that
encourage the development of Helminthosporium diseases. These fungi may spread to
the crowns and roots and cause melting out, which is most severe during periods of hot
weather.
CULTURAL CONTROL
Use turfgrass cultivars with resistance to this disease when available. Planting resistant
cultivars is one of the most effective and economical ways to manage leaf spot and melting
out. Refer to the results of cultivar evaluation trials operated by the National Turfgrass
Evaluation Program or local Universities for cultivars with leaf spot resistance that perform
well in your area. If planting cool-season turf, use blends and mixtures of multiple species
and/or varieties when possible..
Fertilize to meet the nutritional needs of the turf but avoid over-stimulation and the
development of lush, succulent growth. Do not apply more than one pound of nitrogen per
1,000 square feet in a single application. Mowing heights and frequencies should be within
the recommended range for the turfgrass species being managed. Keep the mower blades
sharp to prevent open wounds through which the fungus can enter.
Reduce extended periods of leaf wetness by watering deeply but infrequently to wet the
entire root zone. Use the Turf Irrigation Management System available on Turf Files to
schedule irrigation based on weather conditions and turf needs. Do not irrigate just before
or after sunrise, and ensure good surface and soil drainage. Remove unwanted vegetation
that impedes air movement and prune trees to allow for light penetration. Power rake or
dethatch to remove excessive thatch and reduce the potential for pathogen survival.
Regular aerification and topdressing of golf greens is also necessary to reduce thatch
buildup.
CHEMICAL CONTROL
Leaf spot can be controlled on a preventative or curative basis. However, applications are
most effective when made in the early stages of development. Once the disease reaches
the melting out stage, fungicides may not cure infected plants but will help to reduce
further spread of the disease. Susceptible turfs should be monitored frequently for signs
of disease activity during periods of cool and wet weather.