Spores are dispersed by air currents in greatest number during the middle of the day. Because powdery mildew can cause premature defoliation of numerous plants, it causes alarm for gardeners. This is currently occurring on dogwoods throughout the state. Often infected plants will produce new growth. This new growth may or may not become infected depending upon environmental conditions.
Powdery mildew is most common on plants growing in shady areas.
Since the disease is favored by high humidity, increasing air circulation and light penetration can reduce infection. Overgrown landscapes can be selective pruned to accomplish this. In greenhouses and homes, increasing ventilation and light intensity can reduce disease. Chemical control is seldom recommended in the home landscape. Fungicides protect healthy tissue from infection, they do not cure diseased tissue.