Disease of corn , grasses , onion , and sorghum , caused by many species of fungi (see fungus ).
{{link=spore">Spores accumulate in sootlike masses (sori) that form within blisters in seeds, leaves, stems, flower parts, and bulbs. The sori usually break up into a black powder that is readily dispersed by wind. Many smut fungi enter embryos or seedling plants, develop throughout the plant, and appear externally only as the plants near maturity. Other smuts are localized, infecting actively growing tissues. Control includes growing resistant varieties in noninfested soil, treating seeds with fungicide, using disease-free transplants, and destroying infected plants or plant parts before the spores are released.