Common Smut of Corn
Published: 03/19/2019
Common smut is caused by the fungus Ustilago maydis. 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 galls can form on most corn plant tissues.
Image: D. Mueller
Common smut galls on corn ear.
Image: D. Mueller
Common smut is favored by excess nitrogen, excess manure, herbicide injury, mechanical 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.
Common smut galls can form on stalks, leaves, ears, and tassels.
Common smut gall on leaf tissue.
Later stage common smut gall on leaf tissue.
Common smut galls forming on ear.
Eventually, common smut galls rupture to release dark spore masses.
Common smut galls forming on the tassel.
Common smut galls forming on ear.
Common smut on tassel.
Common smut gall on leaf tissue.
Common smut galls can form on stalks, leaves, ears, and tassels.
Gallery Images: D. Mueller, A. Robertson, G. Munkvold, and A. Sisson
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