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Corn Smut

Ustilago maydis

Corn Smut, Huitlacoche (Mex)

Maisbrand, Maisbeulenbrand (Ustilago maydis) - hms(1)

by Hans-Martin Scheibner. CC BY-SA 3.0

A corn plant infected with corn smut Ustilago maydis
Ustilago maydis is a pathogenic fungal plant disease commonly called corn smut. It mainly affects crop plants such as maize (corn), Zea mays. Infection leads to the production of abnormal growths termed galls, these appear on any above-ground part of the plant and are also called huitlacoche in Mexico, where they are considered a delicacy and consumed as food.
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Some cause small yellow spots on leaves. Some completely distort and stunt the plant's growth. Many causes swelling of certain tissues that when opened are shown to be filled with brown-black spores.

Growth factors

Plant wounds. Hot and dry weather.


Formation of abnormal growths (galls) on above-ground parts.


The spores germinate in the spring and infect young plants through wounds. The fungi multiply inside areas of plants causing them to swell. These swellings will eventually dry out and burst open releasing massive amounts of black spores that infect other hosts.


Keeping good hygiene around plants e.g. removing fallen leaves and burning infected materials. Check the area for signs of previous smut infection. Making sure that plants do not become too dry in hot weather. Keep good air circulation around and through plants. Keep damage to plants a minimum to reduce infection points.
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