Black spot sprays generally control this disease. Black spot causes black spots on the leaves. The leaves turn yellow and drop. Remove and destroy fallen infected leaves. Use Funginex, sulfur, chlorothalonil or basic copper sulfate to control this disease.
Botrytis blight causes flower buds to turn brown and decay.
The petals of unopened flower buds are easily lifted off the stem. Control this problem with chlorothalonil or benomyl. Remove old flowers as they fade. Powdery mildew causes upward curling of young leaves and makes a white, powdery coating on the leaves. Use benomyl, Funginex or sulfur to control the disease.