Other extremes in growing conditions may also contribute. Avoid drought stress. TAMU Bud drop can be caused by too much or too little water or over fertilization. MSU Flowers may be infected with blight caused by Botrytis cinerea. Use sprays of benomyl.
Circular spots occur on leaves which results in their shedding from the plant.
Use appropriate foliar fungicides to prevent damage. If leaf spots are seen, pick off and destroy the infected leaves or use sprays containing basic copper sulfate. If bacterial leaf spot causes problems, pick off and destroy infected leaves. No chemical control is listed. Infection is characterized by yellow-orange pustules on the lower leaf surface.