All aerial plant parts can be infected by powdery mildew, although symptoms are most easily seen on the uppers surfaces of leaves. Infected leaves have white to light grey, powdery patches. These patches may enlarge and cover the surfaces of many leaves throughout a plant, however, infected leaves tend to be most common on the lower and middle leaves. Powdery mildew symptoms may vary among cultivars. Leaves on susceptible varieties may turn yellow, then brown, and fall from the plant.