Black, powdery mold in patches or covering entire upper leaf surfaces. A non-parasitic growth resulting from infestations of aphids or other sucking insects. Use effective insect control. Frequently associated with poorly drained or waterlogged soils. ROSE Rosa spp.
Spots can occur on either leaf surface as well as petioles, twigs and canes.
Infected leaves soon turn yellow and drop from the plant. This results in plants becoming weakened to the point where few blossoms are produced and plant life is endangered. Consistent use of protectant fungicides is necessary for black spot prevention in most areas. The fungus persists in fallen leaves and canes. Destroy all fallen leaves and prune infected canes severely during late winter.