Common Smut

Encyclopedia Article

Description and Symptoms 

Common smut galls can form on stalks, leaves, ears, and tassels; actively growing tissue is especially susceptible. Galls are swollen, distorted growths that are at first covered with a glistening white membrane. The membrane eventually ruptures to reveal a mass of dark brown or black powdery spores. Common smut is favored by excess nitrogen, excess manure, herbicide injury, and relatively dry, warm weather. Some hybrids are less susceptible than others. Avoid mechanical damage from cultivation and herbicide injury to reduce disease risk. Maintenance of balanced fertility also will reduce risk of disease.

Scouting 

The best time to scout is V6 through R6. Incidence is higher among plants grown in soil high in nitrogen or injured by hail, wind, insects, cultivation, or detasseling. 

Management

Foliar fungicides are effective against both common and southern rust, however it is rare for common rust disease severity to be high enough and southern rust to occur early enough in the growing season in Iowa to warrant an application. 

Photo by Daren Mueller

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