How to Prevent and Get Rid of Corn Smut

If you have a backyard garden in one of the warmer growing zones, you’ve likely been left scratching your head a time or two over corn smut.

This disease is a fascinating – albeit troublesome – beast, found typically in small, urban gardens instead of in large, commercial productions. This disease appears on the ears, tassels, stalks, and leaves of the plant, but is most famous for destroying the ears of your corn plants.

Corn smut appears quickly, forming on the plant and releasing thousands of spores that can live in the soil for several years. If you suspect that corn smut is an issue in your garden, you should take immediate action to prevent it from spreading.

What is Corn Smut?

Corn smut is found mostly in Mexico and southern portions of the United States. This disease rears its ugly head in the late summer, just when corn is ready to be picked.

Often, the kernels will become disfigured, looking like knobby messes mixed with black and gray stains. You might notice these unattractive growths on other parts of the plant, but kernels that appear through the husk are generally more common.

Corn smut is caused by the Ustilago zeae fungus. It looks not unlike a mushroom and starts out small, but eventually grows quite large.

While this disease can appear at any time, you will usually notice outbreaks when temperatures rise in midsummer. It often becomes a problem when temperatures range between 80 and 90 degrees.

This disease is caused by fungal spores that are carried by the wind. The significance of this? You might have an infection long before you even suspect that there is a problem.

Unfortunately, ears of corn that are infected with corn smut are usually viewed as inedible in the United States. Interestingly, in some parts of Mexico, ears of corn that are infected with smut are viewed as a delicacy and consumed in a fashion similar to mushrooms. These ears are known as huitlacoche.

Despite this interesting fact, you probably don’t want to have to deal with corn smut in your garden at any time – at least, not unless you have a trade agreement with some interested buyers of the delicacy in Mexico! While corn smut can be difficult to treat, it is luckily relatively easy to prevent.

What Are the Signs of Corn Smut?

Corn smut appears as whitish-gray tumors on your corn. These tumors grow quickly and irregularly, eventually turning black and reaching up to five inches in diameter. These tumors become hard masses and while they usually remain small when found on other areas of the plant, their impact can be devastating.

It’s important that you don’t allow the corn smut tumor to open up. If it does, it will release thousands of spores. Many of these will fall to the ground, but others will be picked up by the wind or water and transported to other plants. What’s even worse is that these spores can remain in your soil, living for up to seven years in dirt and plant debris.

While corn smut more commonly appears in the late summer months, it can appear at any time throughout the growing season on any portion of the corn that is above the soil.

Any corn tissue is vulnerable to this disease, but young tissue that is actively growing is more likely to be infected. Galls will usually first develop on the ears or stalks of the plants before moving on, and will at first be composed of silvery or white tissue. The dark masses of spores appear later.

If a plant has been damaged by corn smut, it will be viewed as inedible. A damaged corn plant will be viewed as inedible in most cases, and even worse, it will spread the disease to other plants around it. Therefore, it is imperative that you take steps to prevent and get rid of corn smut before it destroys your entire patch of corn.

How to Prevent Corn Smut

Corn smut is considered an opportunistic fungus, moving through the tissues of your corn plants rapidly. While corn smut spores are more likely to enter through damaged or torn sections of the plant, they will infect ruthlessly once they get a foothold – even moving on to healthy tissues.

Pick Resistant Varieties

An easy way to prevent corn smut from ever affecting your garden is to only plant resistant varieties. Unfortunately, corn smut can infest all kinds of corn plants, from field (or dent) corn to sweet corn – even popping corn is not safe.

Luckily, there are many types of corn smut that are engineered to be resistant to corn smut. Select these when choosing seeds to plant in your garden as they will have a natural foothold against the destructive corn smut.

Corn smut resistant varieties are adapted for particular growing environments. Because corn smut takes advantage of weaknesses in the plant, it will thrive when the corn is already suffering from external conditions like excessive plant density, corn maturity issues, or drought. Smut-resistant varieties are engineered to withstand these natural stressors.

There are dozens of corn smut resistant varieties you can choose from. Some of the more popular options include:

• Brilliant
• Pristine
• Seneca Snow Prince
• Seneca Sensation
• Seneca Sugar Prince
• Summer Flavor 72W
• Silver Prince
• Fantasia
• Argent

Avoid Damaging Your Plants

A damaged corn plant is much more likely to become a breeding ground for corn smut. If you injure your plant in any way, whether by accidentally cutting it or allowing it to weaken due to poor watering or other factors, you open the door for the corn smut fungus to enter. Take care of your plants, as a healthy plant will have some natural resistance to corn smut.

When you are working near or around your plants, make sure you avoid damaging them in any way. This is especially true if you are using any mechanized equipment or tools around your corn plants, as these can easily cause damage without you noticing. Try to weed by hand in order to give you a greater awareness of potential damage.

Monitor for Pests

Just as injury on a corn plant can provide a potential entry point for corn smut, so can a pest infestation. Pests usually infest plants by boring and chewing into the plant matter. This will create another point of entry for the opportunistic fungus.

Corn borers in particular can be devastating for a corn crop when it comes to providing entry points for corn smut infestation. You can remove these pests manually or use an insecticide to help get rid of them.

Practice Crop Rotation

Make sure you never plant corn in the same spot two years in a row. Because the fungal spores that cause corn smut can live for multiple years in the soil, you should try to find a new spot for your corn plants every year. To be completely safe, make sure you wait at least six or seven years before returning your corn plants to a specific spot. This will provide an absolute guarantee that the spores have disappeared.

Use a Balanced Organic Fertilizer

Try to avoid using fertilizer in your garden that is too heavily comprised of just one component. In particular, high nitrogen fertilizers can make an outbreak of corn smut worse. Therefore, you should try to use a balanced organic fertilizer – like aged compost – instead of a nitrogen-only fertilizer in the garden.

Interestingly, corn that is grown in soil that has high levels of nitrogen, like corn grown in barnyard manure, will be more likely to contract corn smut than corn growing in well-balanced, fertile soils. If you always grow your corn in manure or another organic fertilizer that is high in nitrogen, consider adding a bit of phosphorus. Phosphorus tends to reduce levels of corn smut.

How to Get Rid of Corn Smut

Preventing corn smut is definitely easier than treating it, but if you’re reading this article and trying to figure out ways to get rid of an infection, that’s probably not what you need to hear! Luckily, there are some quick steps you can take now to prevent corn smut from decimating your entire crop.

Remove Infected Plants

For starters, removing any infected plants is imperative. Regardless of whether galls are present on your plants, get rid of the infected plants right away. Whatever you do, do not compost it. Corn smut is famous for being able to survive extremely high temperatures, and the heat of your compost bin won’t be enough to decompose the spores. Once you spread the compost on your garden, it will reinfect the soil for a very long period of time.

Instead of composting the infected portions, remove them immediately. Either burn infected plants or bag them and throw them in the trash.

Avoid Fungicides

Some gardening informational resources suggest treating corn smut with fungicide. While this can be effective very early in the spread of the disease, you have to be on top of your game when it comes to this method of control.

You can use a copper or sulfur fungicide on a weekly basis once you first notice the disease, but if it gets past you at all to the stage of developing tumors, you will likely not be effective with a fungicide regardless of how often or how much you apply.

Unfortunately, fungicides are not an effective method of getting rid of corn smut. While fungicides, whether DIY or store-bought, chemical or organic, can be effective against other fungal diseases, they won’t touch a bad corn smut outbreak. This is because corn smut fungal spores can live in the soil for so long after they have initially been introduced.

Remove Galls Immediately

If you happen to see corn smut appearing, remove the galls right away. If you can get rid of them quickly enough, you will prevent the spores from being released into the air and infecting your other plants. Remember – once the galls burst, they make it possible for thousands of spores to be spread to the rest of your corn.

The sweetest corn is likely the corn you grow yourself. That’s why so many home gardeners choose to grow at least a few ears of sweet corn in the backyard. Unfortunately, corn smut can destroy your corn crop and ruin all of your hard work. Don’t let this happen!

Treating corn smut in the garden is easy, and preventing it is even simpler. Take these steps today, and you’ll be grateful when your corn survives through the summer.

What other tips do you have for preventing, identifying, and treating corn smut in the garden? Be sure to tell us in the comments! And do pin this valuable article on your favorite Pinterest board.