Corn ears infected with a fungus
This fungal disease produces unusual fleshy, moldy growths on stems, leaves, tassels, and ears of corn. The fungus first appears white, then changes to brown and black as it matures and releases spores. It is more commonly seen when the weather is somewhat dry. Corn smut can stunt plants and reduce yields. The disease organism overwinters in the soil and in crop residue. This fungus is considered a delicacy in some Mexican cuisines. The young spongy galls are fried or boiled.
Management
Avoid growing 'Silver Queen', a very susceptible sweet corn variety. There are dozens of varieties that are reported to have resistance to corn smut. Check seed catalogs and seed packets for this information. Remove young galls from plants before they release spores. Do not compost plants with mature galls. Throw them out with your regular trash.