Description: Black spot is a common and potentially serious leaf spot disease affecting many types of roses. Black spot is caused by the fungus Diplocarpon rosae, which survives in rose leaf litter and in infected rose canes. Spores of the fungus are easily spread to newly emerging leaves by wind, or splashing rain.
Organic Control: Products that contain neem oil or potassium bicarbonate are effective, organic controls for many plant diseases.