How to Manage Pests

Pests in Gardens and Landscapes

Common smut—Ustilago maydis

Common smut is easily recognized by the tumorlike galls that form on any aboveground plant part. Galls at first are a glistening, greenish white to silvery white. Galls on ears and stems expand and fill with masses of powdery, dark olive brown to black spores. Galls on leaves and tassels remain small and become hard and dry. Ear and stem galls rupture, and wind, rain, or irrigation water spread them through the garden.

Identification | Life cycle


Remove and destroy tumorlike growths as soon as noticed; keep the black powder in galls from getting into the soil. Plant early as common smut becomes more prevalent in later harvests. All corn varieties are susceptible to common smut to some degree. Try to plant varieties that are the least susceptible to the disease. Rotating out of corn for as long as possible can help reduce overwintering spores in the soil.

Common smut of corn
Common smut of corn

Statewide IPM Program, Agriculture and Natural Resources, University of California
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