Corn Diseases

Growing vegetables takes a lot of know-how and hard work, but the rewards you reap are well worth the effort. While corn is not as popular for home growing as other crops like tomatoes and peppers, it is relatively uncomplicated to plant and an excellent addition to the garden. However, there are many things to contend with within the home garden, including corn disease and pests.

Corn originated in Latin America and is now one of the most popular crops in the United States, with most production concentrated in the Heartland or the high plains, including Illinois, Iowa, Indiana, and South Dakota. However, corn is simple to grow in all other regions, from North Carolina to California.

Sweet corn is a favorite in our household, and it’s even better when we harvest it from the garden. While corn is not as susceptible to diseases and insect damage as many other crops, it is not impervious to plant disease and pests, and it’s vital to know what to look for to ensure a healthy crop.

Growing a Healthy Corn Crop Free of Disease and Pests

There is nothing more upsetting than losing a crop to unforeseen challenges. Fortunately, there are many steps you can take to keep your corn safe from harmful pests and diseases. Learn about some of the most common difficulties you may encounter while growing corn and tips for preventing and eliminating the problems during corn growing time and harvest.

What are the Most Common Corn Problems When Home Gardening?

If you’ve ever peeled back a corn cob while buying ears of corn at your local farmer’s market and discovered a gross worm, you’re already aware that corn is susceptible to pests. Discover some of the more familiar corn problems you may encounter when growing corn in the home garden.

Harmful insects and diseases are typical problems corn plants deal with while growing sweet corn in your garden, and sometimes it’s hard to know which is the culprit. Bugs chew on roots, leaves, and kernels, depriving the plant of nutrients and leaving it in distress, and their activity is usually easy to identify.

On the other hand, when you plant corn in blocks, you often don’t discover that your plant has a disease until the damage is done since diseases live in the soil, spread through the air, or travel with insects.

Ways to Identify Corn Bugs in the Garden

Like other vegetables you grow in a garden, corn plants have to deal with various bugs, and some of them are pretty destructive. Explore which insects are beneficial and identify harmful corn bugs to keep your plants safe.

The most obvious sign that you have corn bugs is the presence of insects feeding on your plants. However, sometimes they hide beneath leaves and are not immediately visible. Check your plants daily for chewed leaf edges or stems, holey leaves, and other forms of destruction.

Bugs that live in the ground are a little harder to detect. Corn seeds that produce weak seedlings or fail to germinate indicate that your garden has maggots, root aphids, or another soil bug.

Is Corn Disease Something to Worry About in a Home Garden?

Corn disease happens from time to time, and there are different types, including bacterial and fungal. Let’s look at these diseases, their causes, and which ones affect corn crops the most.

Bacteria or fungi cause plant diseases, and they generally exhibit symptoms in the leaves. These diseases overwinter in the corn residue or spread on the wind. Some pathogens live in an insect host during the winter. A foliar disease that becomes severe may result in significant yield loss.

Some examples of common fungal diseases are northern corn leaf blight, anthracnose leaf blight, gray leaf spot, and southern corn leaf blight. Bacterial stalk rot, bacterial leaf streak, and Holcus leaf spot are bacterial diseases.

What are Those Black Spots on My Corn Plants?

If you discover black spots on the leaves and husks of your corn, the problem may be tar spot disease. This damage is from the fungus Phyllachora maydis. It overwinters in crop debris and is more prevalent during cool, humid conditions.

According to Purdue University, tar spot is one of the more recent corn problems in the United States and was first confirmed in 2015 in Illinois and Indiana.

Its primary symptom is small, raised black spots on the infected corn leaves. Tar spot thrives during long periods of wetness – avoiding susceptible hybrids and performing crop rotation may reduce the severity of this disease.

What is Bacterial Leaf Streak?

Xanthomonas vasicola PV. vasculorum causes bacterial leaf streak. It is a bacterial disease often confused for other diseases, and it made its first appearance in Nebraska in 2016. It is a bacterial disease observed in sweet corn, field corn, and seed corn.

The symptoms of bacterial leaf streak begin as a narrow lesion with a wavy edge between the veins and corn leaves. The lesions range from one to several inches long and are tan, yellow, brown, or orange. It survives in infected plant material from previous seasons, and the best way to prevent it is to plant resistant hybrids.

The Difference between Common and Southern Corn Rust

Corn rust occurs every growing season, and the southern type is more aggressive than the common rust. They are both similar and spread quickly during favorable environments. However, they don’t usually affect resistant hybrids and do not overwinter in Midwest states.

The Puccinia sorghi fungus causes common rust, and southern rust is caused by the fungus Puccinia polysora. Common rust appears as dark, reddish-brown pustules on both sides of the leaves.

According to Kansas State University, this disease occurs wherever corn is grown, while southern rust thrives in hot conditions and erupts in brown and orange spore masses. Fungicides are relatively effective at treating these diseases.

What Causes Bacterial Leaf Blight?

This disease is caused by the bacterium Pantoea stewartii, spread by corn flea beetles. They carry the bacterium and introduce it to new plants while feeding. Warmer winters predict an increase in this disease during the following season.

Bacterial leaf blight causes long and linear lesions, and young infected plants usually die. Insects and prolonged leaf wetness and cool conditions spread the disease.

Unlike other foliar diseases that start at the lower leaves, leaf blight begins on the upper part of the plant, and flea beetle feeding is often evident in the lesions. The most reasonable ways to prevent this leaf disease from destroying your crops are crop rotation and growing resistant hybrids.

The Destructive Nature of the Corn Earworm

Corn earworms are destructive on several levels. They feed on the silks and kernels of your corn, prevent pollination, and make the corn susceptible to a fungus invasion.

Corn earworms are slightly hairy larvae that range from green and yellow to red and brownish-black. They feed on the ear tips after silking, and once they establish in the ear, they are impossible to control. Pyrethroid insecticides are traditional for dealing with these pests.

What is a European Corn Borer?

If you notice your corn plants have bent stalks and broken tassels and something resembling sawdust around the corn, your crop is dealing with a European corn borer problem. These insects are the larvae of moths and are easy to eliminate if you catch them right away.

Corn borers start as moths that lay eggs on the underside of corn leaves. The corn borer emerges from the egg, and it overwinters as full-grown larvae in stalks and crop residue. To prevent these insects in the future, avoid planting early-maturing corn varieties and cut the stalks close to the ground while harvesting.

The Sneaky Behavior of Corn Root Aphids

These tiny, light green corn bugs feed on the roots of corn plants and remove nutrients, leading to unwelcome root aphid damage. They are dependent on ants for survival, and their activity causes the corn plants to wilt, brown, and even die if the pests are left unchecked.

Corn root aphids are a severe pest in the corn garden, and they rely on cornfield ants, which store aphid eggs in their nests. These ants transfer the hatched eggs to the corn roots in the spring, and the cycle repeats. Neem oil and natural predators are effective at eliminating these insects.

Ways to Prevent Wireworms

Wireworms are click beetle larvae, and they resemble a jointed wire. They are generally present in a newly worked garden and are relatively simple to eliminate by taking preventative steps.

The wireworm has a slender, hard body, and it is a half-inch to an inch and a half long. This yellow to brown pest damages young corn plants, and some species last four to seven years, ruining several successive crops. Flour baits and wireworm-specific insecticides work well to eliminate them.

Companion Planting with Corn to Prevent Disease and Pests

One of the best ways to stop insects and diseases from ruining your crop is to companion planting. Companion plants draw beneficial insects while deterring harmful ones that spread disease, and this practice is excellent for organic gardening.

Companion planting with cucumbers and melons is ideal, as they are vines that spread across the ground to prevent weed growth. Borage, marigolds, and nasturtiums are flowers that attract beneficial insects and deter corn pests.

Dill, mint, and thyme are herbs that repel earworms and prevent deer from eating your crop, and clover is a good cover crop for corn. Winter squash and pole beans are two of the three sisters that provide nitrogen to the soil.

Keep Pests Off Your Corn Plants

Various commercial pesticides work well to get rid of garden pests, but many of these products also kill beneficial bugs. There are other ways to eliminate them. Here are some tips for keeping corn bugs off your plants without harsh chemicals.

Spread a layer of food-grade diatomaceous earth over the soil around your plants. This natural powder slices through the hard outer shell of bugs, causing them to dehydrate and die.

After your corn plants begin to mature and the silks start turning brown, apply five drops of corn oil to the silks of each ear to create a barrier, preventing insects from laying eggs in the corn. Secure a rubber band around the top of each ear to keep the tip of the corn closed for further protection.

Remove the corn stalks from the garden after harvesting them since insects like to overwinter in the plant material.

Ways to Prevent Disease in Your Corn Crop

While some corn diseases are easy to rectify, others are challenging to control and notorious for damaging the entire crop. The ideal way to stop the spread of disease is to take preventative measures while gardening.

One of the best ways to stop your corn plants from suffering from a disease is to ensure the soil pH is correct. Test the dirt and make sure it is 6.0 and adjust it with fertilizer or lime if needed.

Keep the corn garden and nearby areas free of weeds and plant debris. Promptly remove smutted corn ears and discard them away from the healthy plants. Clean the garden at the end of the season and perform crop rotation to stop the spread of disease.

Prepare a Tasty Dish with Corn from Your Garden

You work hard to care for your plants by protecting them from pests and disease, and you’re rewarded with a healthy crop of sweet corn at the end of the growing season. Instead of boiling those corn cobs in a pot of water, like you always do, why not try something a little different?

Combine the butter, Parmesan cheese, smoked paprika, garlic powder, and salt in a medium bowl and spread the butter mixture on each ear of corn. Spread a sheet of parchment paper over a baking sheet and line the corn cobs on top. Bake them for 20 minutes at 420°F without turning, and broil them for the last five minutes.

A lot of hard work and time goes into planting and nurturing a veggie garden, and no one wants to experience a yield loss from corn diseases or harmful bugs. Fortunately, there are simple ways to prevent and remedy these issues before they become a problem.

Growing vegetables is a rewarding experience, and understanding how to prevent corn disease and insect destruction goes a long way to creating a healthy garden, so why not share our corn disease and pest guide with the gardeners in your life on Facebook and Pinterest?