black fungus on an ear of corn

Corn smut infested ear of sweet corn compared to a healthy ear
Whitney Cranshaw, Colorado State University, Bugwood.org

Updated: May 10, 2021

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.

Dried, old corn smut on an ear of corn
Old corn smut on ear 

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.

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