The center of the spot turns gray and drops out. 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.
Botrytis blight causes flower buds to turn brown and decay.
The petals of unopened flower buds are easily lifted off the stem. Remove old flowers as they fade. Powdery mildew causes upward curling of young leaves and makes a white, powdery coating on the leaves. Brand canker develops while plants are under winter protection. Infected roses have a black sooty appearance when uncovered in the spring.