Black spot is a plant disease common in roses.
It is caused by diplocarpon rosae, a fungus that is a severe problem in regions of high humidity and rainfall. Roses will develop circular, black spots on the leaves. The spots will have irregular edges, and be found on the top and sides of leaves in the spring. Often when the tissue of the plant becomes infected, the entire leaf may turn yellow. The infected leaves may droop prematurely, or drop off the plant entirely.