Reports on Plant Diseases |
RPD No. 400 - Recommendactions for the Control
of Diseases of Turfgrasses
| 1989 |
[ Cultural Management ] [
Chemical Controls ] [ Lawn-Type Grasses ] [ Bentgrass
]
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Practically all important diseases of turfgrasses (about 200) are caused
by fungi. One important disease, bacterial wilt and decline is caused
by a bacterium. These largely microscopic, disease-causing organisms lack
chlorophyll and consequently cannot manufacture their own food photosynthetically.
Food is obtained from living or dead plants. Most fungi that live in turf
feed on dead and decaying organic matter, such as dead grass roots, stems,
and leaves, either in the soil or in the layer of thatch. These fungi
are generally considered to be beneficial since they aid in thatch decomposition.
Some of these fungi also attack living turfgrass under favorable temperature
and moisture conditions. Disease-causing fungi may be found in large numbers
on dead and decaying leaves and stems on grass that lacks vigor or is
growing under stress conditions as well as vigorously growing grass. Most
of these organisms are perpetual residents of turfgrass. Weakened or injured
grass plants often lose much of their natural resistance to fungi and
exhibit more disease than vigorous plants, but both can be attacked.
Because fungi need moisture to grow, infect, and reproduce, diseases
are most common and destructive in prolonged wet weather or after frequent
light showers or watering. Most fungi that attack turfgrasses are spread
by microscopic spores, fragments of diseased leaves, and sclerotia carried
on mowers, other turf equipment, shoes, and golf carts. Fungi are transported
over long distances by air currents, splashing or flowing water, insects
and other animals, seed, sod, or plugs; many are capable of growing short
distances on plants or through soil. Fungi are often more damaging in
overly fertilized turf than in moderately nourished or nutrient-deficient
grass.
Intensively managed golf greens and tees or other fine turf areas require
a much higher degree of maintenance and disease control than a highway
shoulder or turf along an airport runway. Major diseases often cannot
be ignored, but many minor ones are more unsightly than deleterious to
the grass.
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Cultural Management
Cultural practices that help reduce disease losses involve a series of
management operations to provide the most favorable conditions possible
for the healthy growth of grass, despite the presence of disease-causing
fungi (Table 1). These help keep fungi in their place and largely prevent
the damaging effect of such diseases as leaf spots and blights, melting-out,
powdery mildew, rusts and smuts, Rhizoctonia diseases, Sclerotinia dollar
spot, snow molds, red thread and pink patch, anthracnose, and seedling
blights. Sound cultural management practices condition turf to withstand
moderate traffic or other physical abuses and recover quickly from various
injuries, insect attack, or disease. Weeds have difficulty competing in
healthy vigorous turf. Turfgrass plants that are in poor health due to
unfavorable growing conditions or poor cultural management practices outnumber
plants that are attacked by fungal pathogens.
Maintenance of quality turf requires a disease management program that
integrates both cultural and chemical practices after seeding, sodding,
sprigging, or plugging.
Table 1. Cultural Management Practices that aid in Controlling Turfgrass
Diseases
|
Cultural Management Practice
|
Diseases Partially Controlled
|
| Provide good surface and subsurface drainage when
establishing a new turf area. Fill in low spots where water may stand.
Before seeding, sodding, sprigging, or plugging, remove stumps, large
roots, construction lumber, bricks, concrete, plaster, tin cans, and
other debris. Uniformly mix into the upper 6 to 8 inches of soil all
soil amendments, e.g., peat moss, calcined clay, etc. Test the soil
reaction (pH) and follow the soil report. A pH between 6 and 7 is
best (5.5 is best for reducing Fusarium patch and take-all patch). |
"Helminthosporium" diseases, summer patch and necrotic
ring spot (Fusarium blight), Rhizoctonia brown patch, Sclerotinia
dollar spot, red thread and pink patch, Typhula blight, Fusarium patch,
Pythium blight, fairy rings, take-all patch, downy mildew or yellow
tuft, spring dead spot, seed rot, seedling blights, Physoderma brown
spot, nematodes, algae, moss, chlorosis, wet wilt. |
| Grow locally adapted, disease-resistant grasses or combinations
(blends and mixtures). Check with your nearest Extension office or
Extension turf specialist for suggested grass species and cultivars
to grow. See also Table 2 for disease resistance of some Kentucky
bluegrass cultivars. In shaded areas, grow shade-tolerant cultivars
or species. |
"Helminthosporium" diseases, rusts, leaf smuts, summer
patch and necrotic ring spot (Fusarium blight), Typhula blight, Fusarium
patch, Sclerotinia dollar spot, powdery mildew, Pythium blight, anthracnose,
take-all patch, nematodes, red thread, Septoria leaf spot, salt tolerance,
traffic, spring dead spot, bacterial wilt and decline, winter injury,
wet wilt. |
| Buy only top-quality sod, sprigs, plugs, or pathogen-free
seed from a reputable dealer. Whenever possible, plant at suggested
rates when the weather is cool and dry. The seedbed should be well
prepared and fertile. Avoid overwatering, especially from planting
to seedling emergence or plant establishment. |
"Helminthosporium" diseases, Pythium blight, seed rot,
seedling blights, leaf smuts, rusts, Sclerotinia dollar spot, summer
patch and necrotic ring spot (Fusarium blight), Typhula blight, Fusarium
patch, yellow patch, yellow ring, nematodes, bacterial wilt and decline. |
| Provide nutrients when the turf is actively growing. Fertilize (supply
nitrogen, potash and phosphorus), according to local recommendations
and soil tests. Recommendations will vary with the grasses grown and
their use. Avoid overstimulation with fertilizer, especially with
a water-soluble, high-nitrogen material, in hot weather. A high level
of potassium (potash) helps suppress disease development. A fall fertilizer
application to dormant turf 1 to 2 weeks following the final mowing
can take the place of an early spring fertilizer application. Slowly
released forms of nitrogen fertilizer are recommended. |
"Helminthosporium" diseases, powdery mildew, rusts, Rhizoctonia
brown patch, Sclerotinia dollar spot, fairy rings, Typhula blight,
Fusarium patch, Pythium blight, summer patch and necrotic ring spot
(Fusarium blight), leaf smuts, red thread and pink patch, anthracnose,
Nigrospora blight, take-all patch, seed rot, seedling blights, Ascochyta
and Septoria leaf spots, downy mildew or yellow tuft, leptosphaerulina
leaf blight, spring dead spots, nematodes, algae, chlorosis, moss
slime molds, bacterial wilt and decline, wet wilt, winter injury. |
| Mow frequently at the height recommended for the area, season, and
grasses grown. Avoid scalping. Remove no more than 1/3 of the leaf
height at one cutting. Keep the turf cut in late fall until growth
stops. Keep the mower blades sharp. |
"Helminthosporium" diseases, powdery mildew, Rhizoctonia
brown patch, Sclerotinia dollar spot, Typhula blight, Fusarium patch,
rusts, summer patch and necrotic ring spot (Fusarium blight), red
thread and pink patch, Ascochyta and Septoria leaf spots, bacterial
wilt and decline, slime molds, wet wilt, winter injury, scalping.
|
| Water established turf thoroughly during droughts. Moisten the soil
to a depth of 6 inches at each irrigation. Repeat every 7 to 10 days
if the weather remains dry. Water as infrequently as possible to allow
gaseous exchange between soil and atmospheric air. Avoid frequent
light sprinklings, especially in late afternoon or evening. Daily
watering may be needed in certain cases to prevent wilt and symptoms
of summer patch and necrotic ring spot (Fusarium blight), Nigrospora
blight, and where parasitic nematode populations are high |
"Helminthosporium" diseases, Rhizoctonia brown patch,
rusts, Sclerotinia dollar spot, red thread and pink patch, powdery
mildew, Pythium blight, summer patch and necrotic ring spot (Fusarium
blight), leaf smuts, fairy rings, Nigrospora blight, nematodes, seed
rot, seedling blights, Physoderma brown spot, anthracnose, take-all
patch, Ascochyta and Septoria leaf spots, leptosphaerulina leaf blight,
slime molds, algae, moss, wet wilt, winter injury. |
| Increase light penetration and air movement to the turfgrass area
and speed drying of the grass surface by selectively pruning or removing
dense trees, shrubs, and hedges bordering the turf area. When landscaping,
space plantings and other barriers properly to avoid too much shade
and increase air movement across the grass. |
"Helminthosporium" diseases, Typhula blight, Fusarium
patch, Rhizoctonia brown patch, Sclerotinia dollar spot, rusts, red
thread and pink patch, powdery mildew, seed rot, seedling blights,
Pythium blight, Septoria and Ascochyta leaf spots, slime molds, algae,
moss. |
| Remove excess thatch in early spring or fall when it accumulates
to 1/2 inch for higher-cut grasses, 1/8 inch for fine turf. Thatch
control will reduce essentially all diseases. Use a vertical mower,
power rake, or similar dethatching equipment. These machines may remove
much live grass when used in areas with a thick thatch. Core aerification
and light top dressing can also be used to reduce thatch. |
"Helminthosporium" diseases, Pythium blight, rusts, summer
patch and necrotic ring spot (Fusarium blight), Typhula blight, Fusarium
patch, Sclerotinia dollar spot, red thread and pink patch, anthracnose,
fairy rings, leaf smuts, yellow ring, yellow patch, nematodes, take-all
patch, algae, slime molds, moss, wet wilt, winter injury.
|
| Core (aerify) compacted turf areas one or more times per year during
the spring or fall period of active turf growth, using a hand aerifier
or power machine. Eliminate foot and vehicle traffic by putting in
walks, fences, shrubbery, patios, parking areas, etc. |
"Helminthosporium" diseases, Pythium blight, rusts, summer
patch and necrotic ring spot (Fusarium blight), Typhula blight, Fusarium
patch, Sclerotinia dollar spot, Rhizoctonia brown patch, anthracnose,
spring dead spot, algae, moss, compaction, wet wilt, winter injury. |
| Follow suggested insect and weed control programs for the area and
grasses being grown. Some insects transmit disease-causing fungi;
weeds may harbor them. |
Applies to practically all diseases. This area has not been studied
extensively by plant pathologists. |
When the cultural practices outlined in Table 1 do not check the
development of turfgrass diseases, a preventive fungicide program may
be needed.
Back to Top
|
Before using any fungicide, you should know what diseases are likely to develop
in your turf. The fungicides to use depend on several factors, such as the type
of grass being grown, disease problems expected, acreage to be sprayed, budget,
available manpower and equipment, and cost of chemicals. Other factors could
include the local distributor or dealer and the chemical companies he works
with, past experience with turf fungicides, and whether or not nearby flowers,
trees, and shrubs need to be treated for foliar diseases.
Turf disease problems vary greatly, depending on the grass or grasses being
grown and the cultural management program (Table 2).
Table 2. Modern Kentucky Bluegrass Cultivars Adapted to Illinois and Reported
to be Moderately to Highly Resistant (R)a to one or More Diseases
|
Kentucky Bluegrass Cultivars
|
"Helminthosporium"
diseases
|
Leaf Smuts
|
Leaf and stem rust
|
Summer patch & necrotic
ringspot
|
Sclerotinia dollar spot
|
Typhula blight
|
Septoria leaf spot
|
Red thread
|
|
A-20
|
R
|
R
|
R
|
R
|
R
|
|
(b)
|
R
|
|
A-34 (Bensun)
|
R
|
R
|
R
|
R
|
|
|
|
|
|
Adelphi
|
R
|
R
|
R
|
R
|
R
|
R
|
R
|
R
|
|
Baron
|
R
|
R
|
R
|
R
|
R
|
R
|
|
R
|
|
Bonnieblue
|
R
|
R
|
R
|
R
|
R
|
R
|
|
R
|
|
Brunswick
|
R
|
R
|
R
|
R
|
R
|
|
|
|
|
Cheri
|
R
|
R
|
R
|
R
|
R
|
|
R
|
|
|
Enmundi
|
R
|
|
R
|
R
|
R
|
|
|
R
|
|
Enoble
|
R
|
|
|
|
|
|
|
|
|
Fylking
|
R
|
R
|
R
|
|
|
|
R
|
|
|
Geronimo
|
R
|
|
|
|
R
|
|
|
R
|
|
Glade
|
|
R
|
R
|
R
|
|
R
|
|
|
|
Majestic
|
R
|
R
|
R
|
R
|
R
|
|
R
|
R
|
|
Monopoly
|
R
|
R
|
|
R
|
|
R
|
|
R
|
|
Nugget
|
R
|
R
|
R
|
|
|
R
|
R
|
R
|
|
Parade
|
R
|
R
|
R
|
R
|
R
|
|
R
|
|
|
Plush
|
R
|
R
|
R
|
|
R
|
|
|
R
|
|
Rugby
|
R
|
R
|
R
|
R
|
R
|
|
|
|
|
Sydsport
|
R
|
R
|
R
|
|
R
|
|
R
|
|
|
Touchdown
|
R
|
R
|
|
R
|
|
|
R
|
R
|
|
Vantage
|
|
R
|
|
R
|
R
|
|
|
|
|
Victa
|
R
|
R
|
R
|
R
|
|
|
|
R
|
a A resistant (R) rating does not mean that a particular cultivar will be
resistant in all locations every year. Due to the presence of physiological
races or strains of the various fungi that cause these diseases, a cultivar
may be susceptible in one locality and highly resistant in another. This is
especially true of powdery mildew and is the reason we omitted this disease
from our ratings.
b A blank under a given disease does not necessarily indicate susceptibility.
In some cases it means that no data are available on which to evaluate the
relative susceptibility or resistance to a particular disease.
Back to Top
One or more broad-spectrum turf fungicides, such as Daconil,
Chipco 26019, and Vorlan may be used to maintain a lawn-type grass, such as a
home or industrial lawn, municipal or state park, airport, athletic turf, school
or church grounds, cemetery, sod farm, fairways and tees, highway shoulders, or
median strip. All of these control "Helminthosporium"-caused diseases
and Sclerotinia dollar spot as well as other less important grass diseases.
If powdery mildew is a problem on Kentucky bluegrass in the shade, you
may wish to add Banner or Bayleton to the above listing.
If rusts are serious in warm to hot weather, Fore, Banner, Bayleton,
and Daconil provide good to excellent control.
Snow molds (Fusarium patch and typhula blight) damage turf in shady
areas and where snow is slow to melt. Products that give good control include
Bayleton, Chipco 26019, and Rubigan. Fungo and Vorlan control Fusarium patch
but not Typhula blight while Daconil controls Typhula blight but not Fusarium
patch.
Summer
patch and necrotic ring spot (formerly called Fusarium blight) are becoming more
severe each year, especially in sunny droughty areas where the turf has a thick
thatch. Banner and Rubigan applied as preventives give good to excellent control
where thatch has been removed, nitrogen is applied, and turf is thoroughly watered
during dry periods. Bayleton and Chipco 26019 are other good preventive fungicides
but one of these products should be combined with Fungo or Cleary 3336 to control
both diseases.
Seed decay (rot and seedling blights) are unusual problems and develop
only with poorly germinating seed, seed planted in an excessively wet seedbed,
and/or unseasonable temperatures. Purchase or treat seed with Captan or Thiram
plus Koban or Apron FL. Apply the same fungicides at early seedling emergence
and repeat at 5- to 7-day intervals. Most turf fungicides do a good job of postemergence
disease control, either alone or mixed with Koban, Terrazole, Chipco Aliette,
or Subdue.
Leaf smuts (largely stripe smut and flag smut) are not a major concern
in Kentucky bluegrass and creeping bentgrass turf areas. The only materials
that provide lasting (or eradicative) control are systemic fungicides (Banner,
Bayleton, Fungo, Rubigan). These materials must be applied in late fall, just
before the grass goes into dormancy. These products need to be drenched into
the soil. Take two applications, 14 to 21 days apart. Carefully follow the manufacturer's
directions on the container label.
If you stock
only one broad-spectrum turf fungicide, choose between Daconil, Chipco 26019,
or Vorlan. When other disease problems are expected, supplement the broad-spectrum
product with one or more disease-specific chemicals.
Back
to Top
If you are growing bentgrasses
on golf or bowling greens, low-cut tees, fairways, or other areas, choose a broad-spectrum
fungicide to control "Helminthosporium" diseases, Sclerotinia dollar
spot, and Rhizoctonia brown patch (e.g., Daconil, Chipco 26019, Vorlan).
In hot humid weather, when Pythium is active, Chipco Aliette, Banol,
Subdue, Koban, or Terrazole do an excellent job, but free water must first be
eliminated. In hot or very humid weather, one or more fungicides effective against
Pythium are often mixed with Daconil, Fore, Chipco 26019, Vorlan, Bayleton,
Cleary 3336, or Fungo to give a more broad-spectrum disease control.
Snow molds damage turf in shady areas, where snow is slow to melt and
no protective fungicide has been applied. Golf course superintendents who are
certified can use Calo-clor or Calo-Gran (both are restricted products) on golf
course greens, tees, and aprons. Otherwise, use one of the products mentioned
for snow mold control under Lawn-type Grasses.
Where Sclerotinia dollar spot is a serious problem on creeping bentgrass,
even where the turf has been adequately fertilized, the systemics (Bayleton,
Rubigan, Vorlan, Cleary 3336, Fungo ) provide the longest and best protection,
but be alert for evidence of resistant strains of the dollar spot fungus. Using
a systemic fungicide in combination with Chipco 26019 or Daconil should solve
the resistance problem.
Leaf smuts are an uncommon problem. For control, see leaf smuts under
Lawn-type Grasses above.
Effective chemical control of turf diseases depends on a
rapid and accurate diagnosis. Experienced golf course superintendents, sod growers,
lawn care company personnel, and other turfgrass managers can usually recognize
or predict the occurrence of common diseases and hence promptly initiate proper
chemical controls. Homeowners, however, are usually unable to diagnose turf diseases
until substantial damage has occurred. The use of fungicides is generally
discouraged in most home lawn situations for several reasons: 1. Proper
diagnosis and selection of the right fungicide to apply is difficult; 2.
It is usually too late for recovery after extensive damage has occurred; 3.
Homeowners often lack the proper application equipment or cannot purchase the
suggested turfgrass fungicide(s) locally; 4. It is probably less expensive
and more satisfactory in the long run to overseed or resod a diseased turf area
with a mixture or blend of disease-resistant cultivars (Table 2) or species; 5.
Lack of application experience and proper certification to handle pesticides;
and 6. Fungicides are mildly to highly toxic and only qualified personnel
should apply them following the manufacturer's directions and precautions as listed
on the container label.
Back to Top
For further information concerning diseases of crucifers
and other vegetables, contact Mohammad Babadoost, Extension Specialist in Fruit
and Vegetable Diseases, Department of Crop Sciences, University of Illinois at
Urbana-Champaign. University of Illinois
Extension provides equal opportunities in programs and employment.
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