Common Corn Smut - Disease
or Delicacy?
Minidoka County
Extension Educator
Corn smut, caused by the fungus Ustilago maydis (DC.) Can. (Syn. Ustilago zeae Ung.), is often considered an unsightly disease but if harvested at the proper time it can be eaten. In fact, it’s considered a delicacy in Mexico.
So what does corn smut look like and how does it develop? According to an Ohio State University extension bulletin the corn plant can be infected at anytime in the early stages of growth. After the ears are formed the corn is less susceptible.
The smut is a formation of galls on the ears, tassels, and nodes. Rarely is it on the leaves, internodes, or aerial roots.
The smut gall is composed of a mass of black, greasy or powdery spores enclosed by a smooth white covering of corn tissue and can be up to 4-5 inches in diameter.
When the spores mature, the outer layer becomes dry and brittle, breaks open, and the spores release.
The spores can remain in the soil for 2-3 years and are spread by wind, by infected seed corn, or by animal manure from infected corn stalks.
The spores (teliospores) germinate in moist air making tiny spores called sporidia. Sporidia, like yeast, buds and forms new spores that germinate in water that collects in the leaf sheaths. The infection (galls) becomes visible after 10 days or more.
To control the disease remove smut galls before they break open and bury or burn. Since wounds on the plant provide a point of infection for the spores, control insects to prevent corn injury and avoid injury to the roots, stalks, and leaves during cultivation. Plant resistant corn if possible.
The larger, later-growing varieties usually are more resistant than the smaller, early varieties.
To see this extension bulletin visit the Ohio State University website at http://ohioline.osu.edu/hyg-fact/3000/3119.html or call me and I will send you a copy.
Purdue University’s website also contains information about preparing the galls for eating if your interested. Visit www.agry.purdue.edu/ext/corn/cgg5/recipes.htm. The site offers information about common corn smut, it’s history, and recipes. It also has some good pictures of the symptoms as well.