Disease Control
Lawn Diseases
Red Thread
Rust
Dollar Spot
Snow Mold
Of all the pests that damage lawns, fungus diseases are
one of the most difficult to tame. There are hundreds of diseases
that can infect your turf. Some are relatively harmless, others
can destroy an entire lawn in a very short time.
Fungus spores spread on the wheels of lawn mowers, on
the shoes of children, on the droplets of rain that bounce
from plant to plant during rain or watering, or blow like
microscopic seeds across your lawn. Every lawn has disease
organisms. The trick is not letting them get the upper hand.
To reduce disease, keep the lawn healthy and growing
with proper feeding, mowing, watering, and thatch control
measures. Some grass types are much less susceptible to fungus
attacks. Consider planting disease-resistant varieties when
you seed.
Disease treatments do not usually eliminate the disease
from the lawn. Instead, they suppress activity for a period
of a few days to several weeks. The goal is to keep the disease
in check long enough for the grass to recover or the weather
conditions to change. Often, several treatments are needed.
Some of the more common diseases facing residents of
Western New York include; snow mold, rust, dollar spot and
red thread. Most of the common diseases are weather-related.
Some of them require control and some don't – most of them can
be handled through good cultural practices.
Puccinia
Thin, weakened turf that appears covered with an orange-red
or yellow powdery dust.
Powder will discolor shoes
and clothing.
All cool season turfgrasses, especially perennial ryegrass.
Warm nights (68-86 degrees F/ 20-30 degrees C), wet leaves,
and low light areas (shady sites or cloudy weather).
Most severe mid to late summer into fall when turf is
not actively growing or under stress.
Maintain adequate fertility.
Minimize leaf wetness.
Avoid drought stress (proper watering).
If you need more help or information with
this topic or any other lawn or tree care questions, please contact
us.
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Sclerotinia homoeocarpa
On closely
mowed turf: Collection of silver dollar size, tannish brown to whitish
spots. Turf appears speckled or mottled.
On residential turf: Collection of 1 inch to 6 inch diameter
bleached white patches.
All cool season turfgrasses.
Warm days (60-90 degrees F/ 16-32 degrees C) and cool
nights above (50 degrees F/ 10 degrees C).
Prolonged leaf wetness, dew, and high humidity.
Dry soils with low nitrogen fertility.
Maintain adequate fertility.
Reduce compaction and limit thatch.
Minimize leaf wetness.
Avoid drought stress (proper watering).
If you need more help or information with this
topic or any other lawn or tree care questions, please contact
us.
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Corticium fuciforme
Coral-pink to red fungus strands may be seen on leaves
and leaf sheaths binding leaves together. Affected turf areas
are usually more or less circular and vary from 2 to 15 inches
in diameter. When dry, the pink strands resemble red threads.
The infected leaf first appears water-soaked, but rapidly
dies, becoming light tan. Leaves, and often the sheaths, are
killed.
Bentgrass, bermudagrass, bluegrass, fescue and ryegrass.
Red thread is most serious during periods of prolonged
cool, wet weather, especially on turf deficient in nitrogen.
The fungus survives unfavorable conditions as pinkish
or red gelatinous crusts of fungus threads. When conditions
are favorable, the crusts resume growth and fungus threads
infect leaves.
If you need more help or
information with this topic or any other lawn or tree care questions,
please contact
us.
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Winter weather conditions are very conducive
to snow mold!
When the snow disappears from your lawn, there may be
areas of weak or dead turf. Often this damage is caused by a disease
known as Snow Mold.
There are two types of snow mold, Gray Snow Mold (Typhula
spp) and Pink Snow Mold (Fusarium Nivale). Both types of snow mold
develop under snow covers or prolonged periods of cool, wet weather.
The optimum temperatures are in the 32 to 45 degree F range for both,
however, the pink snow mold can cause significant damage at temperatures
of 65 degrees. Both snow molds develop most rapidly when snow has fallen
on unfrozen ground.
Where snow mold has been active, the turf commonly develops
rough circular spots of matted, silver-gray turf. Often these spots
are so numerous that an entire area may be disfigured. The trouble
is most likely to be seen on the shaded side of a building, in the
shade of trees and shrubs, or similar areas where moisture remains
for a long time in late winter.
As pink snow mold develops, the initial infections are
irregular patches of pale yellow grass, ranging from two inches to
over one foot in diameter. As the disease develops further, the individual
blades will take on a bleached appearance and the patches become whitish-gray.
For this reason, pink snow mold is often confused with gray snow mold.
Both snow molds develop mycelium (which resemble cob-webs)
that form a white mat under prolonged moist conditions. However, there
is normally more mycelium with gray snow mold.
Once snow mold damage has occurred, the only possible
procedure is to loosen the discolored, matted grass with a leaf rake
(without digging into the soil), fertilize the entire lawn and see
what will develop once good growing weather is at hand. Often the snow
mold fungus kills only the tops of the plants and they recover with
a few weeks of good growing weather. In more serious instances entire
areas of turf, roots and all, will be destroyed and the spots will
not recover. After a few weeks of good growing weather, it is reasonable
to assume that any turf that has not recovered, will not do so. Then
it is the time to do any necessary patching by loosening the soil and
planting more seed. The delay to see what may develop is usually well
worthwhile. Often the most devastating attacks of snow mold will recover
without any reseeding.
If you need more help or information with this
topic or any other lawn or tree care questions, please contact
us.
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