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. Brand canker develops while plants are under winter protection.
Infected roses have a black sooty appearance when uncovered in the spring.
This disease is sporadic and does not directly affect the blossoms or leaves. Destroy infected canes. No chemical control is listed. Brown canker causes cankers with light chestnut brown centers and deep purple margins. Small flecks and purple spots form on the leaves.