Smut diseases on small grains, grasses, onions, herbaceous ornamentals. Smut fungi are Basidiomycetes and include several important genera including Ustilago, Tilletia, Entyloma, and Urocystis . The most economically importance smut diseases are on cereals and grasses.
Smut fungi attack any aboveground plant parts including leaves, stems, and flowers.
Individual florets may be replaced by a spore mass as with loose smut or the whole grain head may be converted into black, smutted masses enclosed within thin membranes as with covered smut. Pictured are chlamydospores of Ustilago maydis .