Fungicides applied in the course of the regular scab spray program will control powdery mildew. Infected leaves turn brown along the leaf margin or tip. The necrotic areas may extend from only a small area at the leaf margin to completely encircle the margin of the leaf. As the lesion matures it becomes gray. Infection can result in leaf shedding from mid July to mid August.
Symptoms develop on a few leaves and then spreads to nearby leaves.
Seldom is the entire tree affected. Because the infected leaves shed, orchard insepections made late in the season are not effective in diagnosing the disease. Several fungi are reported to be the cause of this disease. All of the fungi are controlled with approved fungicides. Fungicide applications applied for scab are effective when applied in early to mid summer.