Abstract
White smut of cosmos caused by Entyloma sp. is one of the most severe plant diseases in Hokkaido. The disease reduces the commercial value of fresh cut flowers and seedlings. In late July, the first symptoms are observed as tiny whitish spots on the surface of the lower leaves. Between 7 and 12 days later, the number of whitish spots increases markedly. Efficient control of the disease can be achieved using the systemic ergosterol-biosynthesis-inhibiting (EBI) fungicides such as imibenconazole, cyproconazole and difenoconazole.
