Corn smut can appear in the stalks, leaves, tassels, or ears. Symptoms are most commonly noticed when the ears produce mushroom-like tumors or galls. These “swellings” begin as small, whitish-gray irregularities that expand and turn black as they fill with spores. Ear galls can grow to 4- to 5-inches in diameter and release thousands of spores as they rupture. These fungal spores are blown by the wind for considerable distances to infect new plants. Galls on leaves remain small and eventually become hard and dry.