AGRICULTURAL EXTENSION SERVICE
University of Florida
Figure 1.-Leaves show-
ing pustules typical of
those caused by rust on
and St. Augustinegrass.
Cover Picture: Brown patch disease on St. Augus-
tinegrass. Close-up shows symp-
toms on leaves.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Agricultural Extension Service, University of Florida,
Florida State University and United States Department of Agriculture, Cooperating
M. O. Watkins, Director
Turfgrass Disease Control Guide
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 concern-
ing occurrence, symptoms and control of the various turfgrass
DISEASES AND THEIR CONTROL
1. Diseases are less likely to cause extensive damage to grass
that has been properly maintained according to recommended
2. Diseases are most likely to occur during periods when the
weather is warm and there is an abundance of moisture. This
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.
moisture may be the result of rain, fog, heavy dews or water-
ing 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 individual
should eliminate the possibility of injury by these causes
before assuming a disease is present. In general, the presence
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
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 in-
jured and the disease not con-
A small amount of wetting
agent, such as a liquid deter-
gent, should be used in the
spray to insure complete cover-
age of the grass foliage. It is
best to spray small areas at a
time to obtain uniform cover-
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.
* It is best to mow the grass before applying a fungicide
(never immediately after).
TURF DISEASES THAT OCCUR COMMONLY IN FLORIDA
Nature of Disease
Grass killed in more or less circular patches that
begin as small spots and may expand to several feet
in diameter. May also cause a thinning of the turf
over a large area. Usually occurs during warm,
humid weather. A root rot may be evident.
Grass killed in distinct patches that are 2 to 3 inches
in diameter. Patches take on a bleached straw color.
In severe cases small patches may coalesce so that
large areas are affected. Leaf spot-type lesions may
be seen on the blades of grass at the outer margins
of the small patches. Occurs during mild to warm
Round to oblong spots on the leaves that are brown
to ash colored with purple to brown margins. Spots
may be covered with a gray mold in warm, humid
weather. Lesions may also occur on the stems. In
severe cases leaves have a scorched appearance.
Prevalent during the rainy summer months.
Small yellow to orange or reddish-brown pustules
on the leaves. Heavily infested turf has an over-all
unthrifty appearance. Prevalent during the warmer
PCNB or thiram
1,000 sq. ft.
Cadmium compounds 1/ oz.
mercury chlorides 1-2 oz.
organic mercury **
An application of a nitrogen
fertilizer will often retard the
Gray leaf spot
TURF DISEASES THAT OCCUR COMMONLY IN FLORIDA (continued)
Nature of Disease
Small oblong purplish to brown spots on the leaves.
Spots may have a tan center. Heavily infected
leaves will wither and die. There is an over-all
thinning of the turf. May occur at any time of the
year when the grass is growing. A rot of the leaf
sheath may be evident.
1,000 sq. ft.
Grass rapidly dies in spots or streaks. In the early Results obtained with fungicides
stage the affected grass is blackened and has a often erratic. Indications are that
greasy appearance. At times the affected spots organic mercury fungicides are most
may have a "cottony" appearance due to the abun- effective. Do not water or mow when
dant growth of the fungus in them. Occurs during disease is active.
warm, humid weather in poorly drained areas.
All grasses Intiaily the grass is stimulated in a circular pattern.
In a few weeks the grass in these areas will begin
to decline. Mushrooms are often present in the
Grass is covered with a gray to black soot-like mold
growth or prominent white or yellow masses. Oc-
curs during warm humid weather.
Difficult to control. Declining areas
often respond to additional fertilizer
and water. Organic mercury
fungicides injected into the soil at
two to three times recommended
rate may give some degree of control.
Grass may be temporarily injured
by such a treatment.
Brush or wash the mold growth off
of the grass. Mowing will eliminate
Turfgrass fungicides may be purchased from dealers for garden and golf course supplies under various trade names. These trade named materials
may contain one or more of the fungicides listed. When using a material containing more than one fungicide (so called broad-spectrum fungicides), use the
rate recommended by the producer.
** Follow manufacturer's recommendation.
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