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Circular 221-E
TURFGRASS DISEASES
AND
THEIR CONTROL
COOPERATIVE EXTENSION SERVICE
Institute of Food and Agricultural Sciences
University of Florida
Gainesville, Florida
May 1974
Figure 1.-Leaves show-
ing pustules typical of
those caused by rust on
ryegrass, bermudagrass,
St. Augustine grass and
zoysiagrass.
Cover Picture: Brown patch disease on St. Augus-
tinegrass. Close-up shows symp-
toms on leaves.
The use of trade names in this publication is solely for the purpose of
providing specific information. It is not a guarantee or warranty of the
products named and does not signify that they are approved to the exclusion
of others of suitable composition.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Cooperative Extension Service, University of Florida and United States
Department of Agriculture, Cooperating, Joe N. Busby, Dean
Turfgrass Diseases and Their Control
T. E. Freeman and R. S. Mullin
Diseases of turfgrass are common in Florida. Each year
they cause the disfigurement of thousands of turfgrass plant-
ings. It is fortunate that much of the damage resulting from
diseases can be avoided or minimized if proper practices are
carried out. Therefore, it is advisable for those interested in
growing turfgrasses to acquaint themselves with factors con-
cerning occurrence, symptoms and control of the various turf-
grass diseases.
DISEASES AND THEIR CONTROL
1. Diseases are less likely to cause extensive damage to grass
that has been properly maintained according to recommended
cultural practices.
2. Diseases are most likely to occur during periods when the
weather is warm and there is an abundance of moisture.
Figure 2.-Bermudagrass severely affected by dollar spot disease. Note
how the small (2 to 3 inches in diameter) damaged areas evident in the
upper part of the picture have coalesced in the lower part, imparting to the
turf in that area a mottled appearance. Inset shows typical leaf spot-type
lesions that can be found on grass affected by dollar spot.
This moisture may be the result of rain, fog, heavy dews or
watering practices carried out by the individual.
3. Many types of injury such as those caused by nematodes,
insects, spilled toxic materials, excess fertilizer and improper
mowing can be confused with disease damage. The individ-
ual should eliminate the possibility of injury by these causes
before assuming a disease is present. In general, the pres-
ence of a disease is indicated when either the grass continues
to decline or the condition spreads to new areas.
4. If a disease is found in a planting of grass, it should be identi-
fied and the recommended control measures started as soon
as possible. (See the following table.)
5. Control of a disease is usually ac-
complished by the use of a fungi-
cide. When using a fungicide the
following points should be kept in
mind:
In most cases it is best to spray
the entire planting and not
just the diseased spot.
The directions and precautions
on the fungicide container
should be followed carefully.
The fungicide should be
sprayed on the area so that
there is complete and even
distribution; otherwise, the
grass may be injured and the
disease not controlled.
A small amount of wetting
agent, such as a liquid deter-
gent, should be used in the
spray to insure complete cov-
erage of the grass foliage. It
is best to spray small areas at
a time to obtain uniform cov-
erage.
Use' enough water to wet the
Figure 3.-Typical appear-
ance of leaves of St. Augus-
tinegrass affected by gray
leaf spot disease.
grass thoroughly. (Ten
gallons per 1,000 square feet is usually sufficient.)
* An application every 10 to 14 days may be necessary to
keep the disease under control.
* Do not mow the grass immediately after applying a fung-
icide.
KEY FOR IDENTIFICATION OF TURF DISEASES
I. Grass affected in distinct patches.
A. Affected areas 2 to 3 inches in diameter.
Leaf spot-type lesions present ..........................Dollar spot
B. Affected areas usually larger than 2 to 3
inches in diameter. Leaf spot-type lesions
not present.
1. Mushrooms present in circular pattern........Fairy ring
2. Mushrooms not present in affected area.
a. Affected areas tend to be in streaks.
Grass blades matted together.
Primarily on ryegrass and
bermudagrass ....---....--.......---.........-- Cottony blight
b. Affected area more or less circular.
Grass blades usually not matted
together .-.......................---------------..Brown patch
II. Grass not affected in distinct patches.
A. Orange pustules present on leaf blades .........-.............-Rust
B. Orange pustules not present on leaf
blades.
1. Leaf spots present.
a. Leaf spots generally less than
1/16 inch in diameter. Leaf
sheath may be rotted................-- Helminthosporium
leaf spot
b. Leaf spots frequently larger
than 1/8 inch in diameter.
Primarily on St. Augustinegrass......Gray leaf spot
2. Leaf spots not present. Grass
covered with a sooty-like hard
mold growth ............................................. Slime mold
TURF DISEASES THAT OCCUR COMMONLY IN FLORIDA
Control
Disease Grasses Nature of Disease Con
Affected Fungicide* Rate per
to use 1,000 sq. ft.
Brown patch St. Augustine, Grass killed in more or less circular patches that Daconil 2787 4 oz.
(Rhizoctonia bahia, rye, begin as small spots and may expand to several feet Fore 4 oz.
solani) bermuda, in diameter. May also cause a thinning of the turf Tersan 1991 2 oz.
zoysia, over a large area. Usually occurs during warm, thiram 4-6 oz.
centipede humid weather. A root rot may be evident. PCNB 6-8 oz.
Dollar spot St. Augustine, Grass killed in distinct patches that are 2 to 3 inches
(Sclerotinia bermuda, in diameter. Patches take on a bleached straw col- Daconil 2787 4 oz.
homoeocarpa) zoysia, or. In severe cases small patches may coalesce so
bahia, that large areas are affected. Leaf spot-type lesions An application of a nitrogen fertilizer
centipede may be seen on the blades of grass at the outer mar- will often retard the disease.
gins of the small patches. Occurs during mild to
warm humid weather.
Gray leaf spot St. Augustine, Round to oblong spots on the leaves that are brown
(Piricularia Rye to ash colored with purple to brown margins. Spots Daconil 2787 4 oz.
grisea) may be covered with a gray mold in warm, humid Dyrene 4 oz.
weather. Lesions may also occur on the stems. In Fore 4 oz.
severe cases leaves have a scorched appearance. thiram 4 oz.
Prevalent during the rainy summer months.
Rust rye, Small yellow to orange or reddish-brown pustules
(Puccinia bermuda, on the leaves. Heavily infested turf has an over- Tersan LSR 4 oz.
spp.) St. Augustine all unthrifty appearance. Prevalent during the zineb 2-4 oz.
zoysia warmer months.
TURF DISEASES THAT OCCUR COMMONLY IN FLORIDA (continued)
Control
Disease Grasses Nature of Disease
Affected Fungicide* Rate per
to use 1,000 sq. ft.
Helmintho- bermuda, Small oblong purplish to brown spots on the leaves.
sporium zoysia, Spots may have a tan center. Heavily infected Daconil 2787 4 oz.
(Helmintho- St. Augustine, leaves will wither and die. There is an over-all Fore 4 oz.
sporium spp.) rye thinning of the turf. May occur at any time of the Tersan LSR 4 oz.
year when the grass is growing. A rot of the leaf
sheath may be evident.
Pythium blight rye, Grass rapidly dies in spots or streaks. In the early
(Pythium bermuda stage the affected grass is blackened and has a
aphanider- greasy appearance. At times the affected spots may Koban 4 oz.
matum) have a "cottony" appearance due to the abundant Tersan SP 4 oz.
growth of the fungus in them. Occurs during warm,
humid weather in poorly drained areas.
Fairy ring All grasses Initially the grass is stimulated in a circular pat- Difficult to control. Declining areas
(Lepiota sp., tern. In a few weeks the grass in these areas will often respond to additional fertilizer
Marasmius sp., begin to decline. Mushrooms are often present in and water.
etc.) the areas affected.
Slime mold All grasses Grass is covered with a gray to black soot-like mold Brush or wash the mold growth off
(primarily growth or prominent white or yellow masses. Oc- of the grass. Mowing will eliminate
Physarum sp. and curs during warm humid weather. (Technically the condition.
Fuligo sp.) not a disease)
Recommendations may change with the appearance of newer fungicides. Your county agent can advise you on these changes.
I
This public document was promulgated at an annual cost of $1,297.63, or
8 cents per copy to present information on controlling diseases of turfgrass.
Single copies free to residents of Florida. Bulk rates available upon request.
Please submit details on request' to Chairman, Editorial Department,
Institute of Food and Agricultural Sciences, University of Florida,
Gainesville, Florida 32611.
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