Kentucky bluegrass, perennial
ryegrass, tall fescue
Lawns damaged by southern blight have large, crescent to circular
areas of damaged turf up to several feet in diameter. The turfgrass
turns reddish-brown as it dies. Some plants may remain green in the
center of the affected area. As the disease develops, white mycelia
appear on grass blades and stems and light to dark brown sclerotia
develop at the base of stems. The sclerotia, which resemble mustard
seeds in size and shape, are key to diagnosing the disease.
Conditions favoring disease
Warm or hot temperatures (85° to 95°F), high moisture,
and heavy thatch favor the development of southern blight. The fungus
survives in the thatch as sclerotia.
Prevention and management
Follow proper irrigation and fertilization
requirements for your turf species. Southern blight is less
destructive on a vigorously growing grass. Control thatch.
Use clean equipment when aerating or
dethatching because these practices can spread the sclerotia. Fungicides
may be useful in areas where the disease has been a problem in
For more information on lawn diseases, refer to:
Pest Notes: Lawn Diseases:
Prevention and Management