Plant Pathology Fact Sheet
Monica L Elliott, Associate Professor, Ft. Lauderdale Research and Education
Center, University of Florida, 3205 College Ave, Ft. Lauderdale, Fl 33314. and
Gary W. Simone, Professor Emeritus, Plant Pathology Department, University of
Florida, Gainesville, Florida, 32611. Revised April 2001
Florida Cooperative Extension Service/ Institute of Food and Agricultural Sciences/ University of Florida/ Christine Waddill, Dean
All warm-season turfgrasses.
This disease is most likely to be ob-
served from fall through spring. It will only be
observed on turfgrass areas with sub-optimal
nitrogen levels for that particular turfgrass spe-
cies. Other factors associated with the disease
are a dry root system combined with a humid
leaf canopy. The humid leaf canopy may be
due to either high air humidity, light rainfall or
too little irrigation applied too frequently at the
wrong time. See information on water and dis-
Small (1-3 inches diameter), brown to
straw-colored patches of dead grass will de-
velop (Figure 1). Irregular, light tan lesions with
distinct brown borders will be present on the
leaves at the outside edge of the patch (Figure
2). The small individual patches do not expand
in size, but as the number of patches increase,
they may merge together to form larger patches.
White, cottony mycelia may be observed in
early morning hours when dew is present.
Prevent the disease by avoiding extreme
nitrogen deficiency. Use slow-release nitrogen
fertilizers, and balance the nitrogen with potas-
sium, preferably a slow-release potassium
form. During dry weather, apply adequate
water so the root-zone is fully saturated each
time you irrigate. Irrigate during the early
morning hours (2 to 8 AM) when dew is already
If the disease is already present, apply a
quick-release source of nitrogen (12 pound N
per 1000 square feet). Examples would be am-
monium sulfate, ammonium nitrate or quick-
release urea uncoatedd urea). Follow-up with
an application of slow-release nitrogen, bal-
anced with potassium. This is just as effective
as fungicides on warm-season turfgrasses. If
the soil is dry, irrigate to fully saturate the root
chlorothalonil, iprodione, mancozeb,
myclobutanil, PCNB, propiconazole,
thiophanate methyl, thiram, triadimefon,
Mancozeb can be applied to a residen-
tial lawn only by a professional pesticide ap-
plicator. Chlorothalonil, thiram, and
vinclozolin cannot be applied to a residential
lawn, but they can be applied to turfgrass in a
business or industrial landscape.
Refer to "Turfgrass Disease Management" PPP-
64 for explanations of chemical and cultural
rlfUMet -1. UUIIal opul s ymlpiLuIn Ulfn t.
Augustinegrass. Note that the patch is very
small (-3 inches) compared to Brown Patch
symptoms figure 2 and 3 PP-20.
Figure 2. Leaf lesions due to D
disease on St. Augustinegrass.
rlgure 3. UOlldF iUc UINCd eate -UlIL WILII
either a fungicide(left) or by adding a quick-
realese nitrogen fertilizer(right).