Symptoms. In warm weather, when the soil is dry but the canopy is moist, the fungus colonizes the older leaves. This causes the leaves and their stems to die faster. Plants are killed in irregularly shaped patches. The patches are an inch to a few feet in diameter. The patches are first reddish-brown, then yellow, next light brown, and finally darker brown. . Leaves have oblong reddish-brown leaf spots or may turn completely yellow. The disease progress up the stem with older leaves affected first. Within the leaf spots are spiny black spots, which are the fungal fruiting bodies.
During cool, wet periods (60o-75o F) in late spring and early summer, a basal rot develops. This can affect individual plants scattered throughout the turf, or clusters of plants in patches that can reach 6 inches or more across. An individual plant can have infected and uninfected tillers. The edges of the patches are irregular. The patches are a grayish-green color, and fade to tan.
The basal rot begins as a watersoaked spot on the stem. These spots then become bleached and ultimately grow completely around the stem. The leaves turn yellow, then light brown, and die, starting at the tips, and progressing down the leaf. The central, youngest leaf remains green the longest. It later may turn yellow, orange, and then red. A black rotting of the base of the plant occurs. This causes the top to be easily pulled from the roots.
Prevention. Adequate fertilizer and water are important to control this disease, especially in hot, humid weather. It is especially important to avoid potassium and phosphorous deficiencies or excessive nitrogen. Avoid fertilizing during drought or hot weather. Water early in the day, as deeply and infrequently as possible. Avoid soil compaction and aerate soil by spiking.
Some cultivars of annual bluegrass are less susceptible than others. Turfgrasses other than bluegrass are not as susceptible.
See current recommendations for chemical control measures.
By Pamela S. Mercure, IPM Program Assistant, University of Connecticut, 1998
Smiley, R.W. 1983. Compendium of Turfgrass Diseases. APS Press, St Paul, MN.
Smith, J.D., N. Jackson, and A.R. Woolhouse. 1989. Fungal Diseases of Amenity Turfgrasses, Third Edition. E. & F.N. Spon, London.
Turgeon, A.J. 1996. Turfgrass Management, Fourth Edition. Prentice Hall, Upper Saddle River, New Jersey.
This information was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.
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