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Corn Smut: Good or Bad?

Updated on November 9, 2017
OldRoses profile image

Caren White is a Master Gardener and longtime volunteer at Rutgers Gardens as well as an instructor at Home Gardeners School.

Immature Corn Smut
Immature Corn Smut | Source

A gardener or farmer here in the U.S. who checks their corn crop and finds corn smut despairs. The crop is ruined and must be destroyed. A gardener or farmer in Mexico who checks their corn crop and finds corn smut is elated. A delicious treat for their table or market has appeared in their crop.

Why the difference in reaction between the U.S. and Mexico?

What is corn smut?

Corn smut is a fungus (Ustilago maydis) that infects all parts of the corn plant. It won’t kill the plant, but it will reduce the yield. The fungus is spread through spores that fall to the ground where they can survive in the soil up to seven years. When it rains, the spores are splashed onto the plants, infecting them. The spores can be spread on the wind to infect corn that is not immediately adjacent. They can also be spread through manure from animals who have eaten infected corn.

After infecting a plant, the fungus forms galls that range in size from a pea up to five inches. The galls form where the spores have landed on the plant and can appear on the stalk, the leaves or the tassels but are largest and most apparent on the ears. In the ears, the galls form between the kernels. They are white as they begin to develop but as they mature and fill with black spores, they turn brown or black. Fully mature galls rupture, spilling their spores on the ground or if it is a windy day, the spores will be blown on the breeze spreading infection to neighboring fields.

Mature corn smut filled with spores
Mature corn smut filled with spores | Source

How do I get rid of corn smut?

There is no treatment for corn smut. Once a plant has become infected the only remedy is to remove the entire plant immediately from your garden and destroy it. Don’t wait for fall. It is important to destroy the galls when they are young before they have formed spores that can spread the infection. Do not compost infected plants. This will only result in spores being spread as you add compost to your garden the following year.

The best “cure” is prevention. Clean up and destroy all garden debris in the fall to prevent spores from overwintering in the soil. Practice crop rotation. Plant your corn in a different bed every year. Try planting sweet corn varieties that are bred to be resistant to the fungus such as Silver King, Seneca Sensation or Fantasia.

Corn smut for sale in a Mexican street market
Corn smut for sale in a Mexican street market | Source

Is corn smut edible?

Yes! In Mexico it is considered a delicacy. Farmers will sometimes deliberately infect their corn crop to produce the edible galls. The galls can be purchased fresh in markets and stands or canned in grocery stores. They are usually used in fillings for tortillas and in soups but can also be eaten fresh. The galls are harvested when they are white before they mature and fill with spores. The taste is similar to mushrooms.

Empanada with corn smut filling
Empanada with corn smut filling | Source

Attempts have been made to introduce this local delicacy into the United States. The galls have even been renamed to Mexican Truffle to entice consumers. They have been slow to catch on. There is a very small quantity available because the USDA has devoted tremendous resources to eliminating corn smut from American corn. Perhaps they should instead devote some of those resources to encouraging Americans to eat corn smut rather than destroy it. It’s certainly an organic solution to a common fungal infection.

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    • OldRoses profile image
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      Caren White 2 weeks ago from Franklin Park, NJ

      Glad you found it helpful. I think corn smut has been around in the US longer than the USDA. Thanks for reading and commenting.

    • Blond Logic profile image

      Mary Wickison 2 weeks ago from Brazil

      I am surprised the US ever allowed them in, as their rules are stringent. I think it was in the 70s or 80s when the Mediterranean fruit fly was found in California. The whole of the LA basin (crops and houses) were sprayed by planes with insecticide. California is called the breadbasket of America and any potential threat to crops would be devastating to the ecomony.

      I've never seen such a thing before and I grew up around many cornfields, although there was spraying.

      My neighbor says I should try growing corn this year here in Brazil. Now if I see this fungus I will recognize it.

      Seven years is a long time for it to stay in the ground. This was very interesting and now I'll stay on the alert for it.

    • OldRoses profile image
      Author

      Caren White 2 weeks ago from Franklin Park, NJ

      Demas, you're welcome! Thanks for reading and commenting.

    • Perspycacious profile image

      Demas W Jasper 2 weeks ago from Today's America and The World Beyond

      An interesting Hub devoted to a specialty concern. Thanks.