What Is Corn Smut Fungi (Huitlacoche) & How to Prevent It

Have you ever grown corn, and when you went to harvest it, you were shocked, disgusted, and horrified by large black, blue, or grey growths on your corn? That is called corn smut!

Troubleshooting Garden Plant Diseases

I’ve already shared how to plant corn, the types of corn, and when to harvest corn. Now, it’s time to discuss what to do when things don’t grow according to plan.

Knowing how to recognize and troubleshoot things like tomato blight, powdery mildew, blossom end rot, and corn smut will go a long way toward having a thriving garden.

What is Corn Smut Fungi (Huitlacoche)

Corn smut (Ustilago maydis) is a fungal disease that affects corn plants. The fungus usually infects corn kernels, causing them to swell and form grayish-black masses known as galls.

Surprisingly, this fungus is edible and, I’ve heard, even delicious. Corn smut, or huitlacoche as you may hear it called, is considered a food product more than an undesirable corn disease in Mexico.

As you can image, there are mixed feelings about whether huitlacoche is a threat to American agriculture and should be suppressed or if it is a viable crop that should be intentionally cultivated.

Life Cycle & Cause of Corn Smut

The fungus that causes corn smut thrives in warm, humid conditions. It is most common in areas with mild winters and wet summers.

The fungus can survive in the soil for several years. From there, wind, insects, or water transport the spores to other plants. It can also be spread through contaminated seed, equipment, or soil.

The most common type of infection occurs in an ear of corn when a spore lands on the silk and grows into the kernels. This causes them to swell and form silvery tumor-like structures known as galls.

These galls can grow quite large and are filled with a black, powdery spore mass. Eventually, the galls burst and release thousands of spores that spread to the soil and other plants.

Preventing Corn Smut Fungi

To prevent corn smut fungi, you should practice good crop rotation, using different fields for corn each year. Also, avoid planting in areas recently affected by the disease.

Using disease-free corn seed and ensuring proper sanitation of equipment and tools are also important steps in preventing corn smut. You could also buy corn that has been treated with a biofungicide; however, this is often not available for home gardeners, and when it is, it is NOT organic.

Home gardeners can also use fungicides to prevent infection with limited success. However, fungicides must be applied at the right time and in the right amount to be effective.

Applying fungicides too early or too late in the growing season, or using the wrong type of fungicide, can result in ineffective disease control. Regardless of organic or inorganic application, studies show mixed results with application, so I would recommend not spending the time or money on it.

Another preventive measure is to remove and destroy any infected plants. This will help reduce the amount of spores in the environment and make it less likely that the disease will spread to other plants.

Eating Huitlacoche

If you do end up with huitlacoche, maybe consider trying some! At least you won't be wasting any food.

It is often eaten in quesadillas and tacos and is said to have a unique, earthy, smoky taste similar to a truffle or mushroom. Hey... when life hands you lemons, sometimes you need to make lemonade!