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.
This disease is sporadic and does not directly affect the blossoms or leaves. Destroy infected canes. Brown canker causes cankers with light chestnut brown centers and deep purple margins. Small flecks and purple spots form on the leaves. This disease attacks canes while the roses are under winter protection.