What are the reddish-orange spots on the leaves of my rosebush?
A. These spots are caused by a fungal disease, called rust, which covers leaves with tiny spore cases that resemble curry powder. Affected leaves always wilt and then fall off. Rust can defoliate and seriously weaken or even kill rose bushes. The disease occurs most frequently at temperatures between 18-21 degrees Celsius accompanied by 4-12 hours of rain, fog, or dew. At the first sign of rust, remove and destroy all infected leaves. Spray plants with Garden Sulfur as a control measure. Q. What are the black spots on the leaves of my rose bush? A. This is one of the worst rose diseases: blackspot. A fungal infection, it causes the leaves to get these black spots with fringed margins which then turn yellow and fall off. Rose bushes are defoliated from the lower leaves upward. It is most prevalent on warm humid days at temperatures between 20-24 degrees Celsius. The spores are spread by splashing water, and quickly develop when they land on wet leaves, so try to avoid wetting the foliag
