Common smut

Greenish white to silvery galls form on all parts of the plant but are most common on ears. Galls turn gray with maturity and rupture releasing dark olive brown to black spores. Teliospores remain viable in the soil for many years. In Kansas, smut is most severe in hail-damaged corn, or during extremely hot, dry weather that inhibits pollination. Sweet corn is more susceptible. Resistant hybrids are the only effective method of control.

Taken from Corn Production Handbook, KSU Extension