Powdery mildews are common on many kinds of plants. Although they may look the same, each kind of plant is infected by a different species of powdery mildew fungus. Powdery mildew fungi on grasses will not infect lilacs, phlox, roses or other garden plants.

Symptoms:
Powdery mildew may appear quite suddenly, usually in shaded areas, and most commonly on Kentucky bluegrass. The grass blades look as if they were dusted with flour or lime. The white to gray powder is a combination of the mycelium and spores of the powdery mildew fungus. The mycelium grows over the surface of the leaf, absorbing nutrients from the plant. Later, the leaf may turn yellowish and begin to dry up and die, but the leaves often support the presence of the powdery mildew fungus for some time without significant injury. Powdery mildew is most common in turf from July to September, and occasionally in the spring. It is most common during overcast periods of cool, moist weather.

Life Cycle:
Powdery mildew fungi overwinter on infected grass plants and in survival structures on dead grass. Spores can infect leaves in less than two hours, and new spores are produced in abundance in about a week. Air currents carry the spores to new grass plants. Disease development can be so rapid that powdery mildew may seem to appear very suddenly.

Cultural Management:
Powdery mildew is usually a disease of shaded turfgrass. Similar grasses growing nearby in full sun usually will remain free of powdery mildew. To reduce shade and increase air circulation, prune shrubs and tree branches. If grass is thin or weakened in shady areas, re-seed with shade-tolerant grass species and select cultivars resistant to powdery mildew. If grass is growing very poorly due to shade, consider its replacement with shade-loving ground covers such as hosta, pachysandra or lily-of-the-valley. In moist, shaded areas of lawns, powdery mildew may be prevented or reduced by careful lawn care. Avoid excess nitrogen fertilizer, raise the mowing height and water deeply but infrequently. Avoid frequent, light sprinkling.

Solutions
Eagle, Myclobutanil, Banner Maxx, PrimeraOne Propiconazole, Trinity, Instrata, Headway, Armada, Tartan, Bayleton