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. Brown canker may be worse on bushes hilled with soil. Common stem canker gains entrance through a wound. Young cankers are pale yellowish or reddish, becoming brown, sunken and cracked.