Symptoms. Small (2" to 6") patches of turf become pale and may wilt. They then turn slightly reddish, then tan , then straw-colored. The patches can grow to 12" across and are circular to irregular in shape. A dark brown to black, dry, firm rot is present on the roots, crowns, and bases of the stems. In warm, wet weather, white to pink masses of cottony to powdery fungal growth and spores may appear.

Leaf spots may or may not be present. They begin as irregularly shaped dark-green blotches, and quickly become light green, then reddish brown, then dull tan. They have light colored edges. The centers may ultimately become bleached white. The spots can be almost 1/2" in length, and may reach across the entire leaf blade.

Prevention.

• Mow at the recommended height, mowing lower can stress the plants and predispose them to this syndrome.
• Remove thatch if it is deeper than 3/4".
• Remove clippings.
• Keep the pH of the thatch and the soil at 6 to7 by adding small amounts of lime or sulfur regularly if necessary.
• Apply balanced fertilizers, and avoid deficiencies of phosphorous and potassium.
• Avoid excessive nitrogen, especially in spring and summer.
• Water as deeply and infrequently as possible.
• Water in the early part of the day to allow leaves to dry thoroughly.
• Including perennial ryegrass in mixtures of Kentucky bluegrass helps reduce the occurrence of this disease, and helps mask the disease symptoms.
• See current recommendations for chemical control measures.

By Pamela S. Mercure, IPM Program Assistant, University of Connecticut, 1998.

References.

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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