Small to large areas of the lawn, especially in shady to partial shade locations, show symptoms of grass being dusted with flour or talc. As the disease progresses, turfgrass blades wither and die. Powdery mildew is caused by a fungus. It is not considered to be a serious disease on turf, but is more of an esthetic problem. Sever outbreaks tend to occur in shaded areas in late spring through fall. High humidity and temperatures above 60 degrees favor this disease. Increase sunlight penetration by pruning trees and shrubs to allow more light to infected areas. Adjust water so that areas prone to the disease will stay drier. Fungicides can be applied as a preventative before the disease becomes established. Blades already infected will not benefit from chemical treatments.