Anthracnose is a stress-related fungal disease that infects most turfgrasses.
Conditions such as soil compaction, poor soil drainage, low nitrogen, traffic
and dry soil stress turf and contribute to the development of the disease.
During warm weather when the soil is dry, but the canopy is moist, the fungus
grows in the older leaves. Irregularly shaped patches form in the turf, ranging
from an inch to a few feet in diameter. Initially, the patches may be red brown,
then progress to yellow or tan, and finally dark brown. Red-brown, elongated
leaf spots may be visible on individual blades. Spiny, black fruiting structures
are easily found on the older leaves.
In cool wet weather, anthracnose basal rot develops. Leaves turn yellow,
brown and then die beginning from the top down and with the older leaves first.
As the base of the plant rots, it darkens and leaves pull out easily. These
leaves, too, have a darkened base. Sometimes plants appear orange or red during
this stage.
To manage the disease, water turf deeply and infrequently. Shallow, frequent
watering may keep the soil dry and the canopy moist, creating ideal conditions
for disease development. Be sure there is adequate sprinkler overlap to avoid
dry spots.
Fertilize turf 3 to 4 times per year, applying 1 pound of nitrogen per 1000
square feet at each application. Core aerate once or twice per year (spring,
fall) to reduce soil compaction and improve drainage and aeration. Regularly mow
turf to a 3 -inch height throughout the growing season.
Fungicides available for home use include propiconazole, thiophanate-methyl
and triadimefon. Always follow label directions. Fungicides are a tool in
disease management. If the underlying problems contributing to disease
development are not addressed, anthracnose will continue to be a problem.
