UCONN IPM Turf:Diseases:Powdery Mildew

Powdery Mildew of Turfgrass

Powdery mildew, caused by the fungus, Erysiphe graminis, affects Kentucky bluegrass and other bluegrass and fescue turfgrasses. This disease is favored by shaded conditions, especially if there is little air movement. It usually occurs during spring and autumn and is favored by cool, (65^o F), humid, cloudy weather.

Symptoms. Whitish, talcum-like growth is present on leaves and leaf sheaths. The growth begins as small patches on the leaf, but will cover large portions of the leaf if conditions are favorable for fungal growth. It grows more heavily on the upper leaf surface than on the lower leaf surface. Large patches of infected grass look as if flour or lime were sprinkled over them. If leaves are infected heavily, they turn yellowish, and then tan to brown as they die. The plants are weakened and may be killed by other diseases or drought stress.

Prevention.

The use of shade-tolerant grasses in the mixture when planting in shady areas is key in preventing this disease in these areas.
Some areas may be too shady to plant turf.
Prune trees and shrubs to allow more light to reach the turf and improve air circulation.
Avoid excessive nitrogen fertilizer, but fertilize sufficiently to promote vigorous growth.
Mow grass frequently, but relatively high in mildew-prone areas.
Water as needed.
See current recommendations for chemcal 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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