Corn Diseases + Picking Hybrids for 2026

2025 was a terrible year for disease in corn…

With high humidity and many hours of leaf wetness from heavy dews and/or frequent rains, the stage was set for foliar diseases. Let’s take a look at how disease protection plays into corn hybrid selection for 2026.

BACTERIAL DISEASES

There are a number of bacterial diseases of concern for corn fields across the U.S., most notably Goss’s Wilt, Bacterial Leaf Streak (BLS), and an up-and-comer, Corn Stunt Disease. With Corn Stunt, it’s spread by corn leafhoppers, which makes it unique. Spray the leafhoppers and stop the disease spread. Bacterial Leaf Streak is not thought to be a major economic yield robber, but managing crop residue, limiting irrigation at certain times of the season, washing equipment when moving from field to field, and crop rotation can reduce its impact. Goss’s is another story.

If Goss’s Wilt is a problem in your area, choose a hybrid with good to excellent tolerance to the disease. That’s by far your best way to manage it. Fortunately, hybrid tolerance ratings are available on every corn hybrid and building more tolerance to Goss’s has been a focus of most major corn breeding programs. Researchers have developed inoculation practices to induce Goss’s, so they can get good comparative ratings between hybrids.

FUNGAL DISEASES

In the Upper Midwest, gray leaf spot and northern corn leaf blight have gotten all the attention for as long as I can remember. Hybrid tolerance to each of these diseases is something to select for as corn breeders have good screening capablities and many years of experience working with them. One other tool that has been helpful fighting gray leaf spot and northern corn leaf blight has been Xyway fungicide at planting time. Its systemic movement within the corn plant well into the season has been a great foundation for stopping these pathogens, as well as others like tar spot. While you will still need a foliar fungicide application when disease pressure is heavy, it’s tough to beat having Xyway’s protection to start the season.

The other two diseases that are the most problematic heading into 2026 are tar spot and southern rust. Tar spot thrives in moderate temperatures and high humidity. Southern rust thrives in high temperatures and high humidity. It sure seems like one or both of these diseases could be in play most growing seasons. HERE’S THE LOWDOWN.

TAR SPOT – Bayer has an inoculation for tar spot they can use in their testing which is incredibly helpful for them to eliminate susceptible hybrids. I would guess the other major breeders will have a way to inoculate hybrids in their research soon, too. My estimation is one in eight hybrids has a strong tolerance to tar spot now, so if you’re picky and do your homework, you can put together a good mix of varieties on your farm. However, foliar fungicides are effective on this disease, so if your favorite hybrids are good but not great on tar spot, you can still protect them with timely fungicide applications.

SOUTHERN RUST – This disease is well known in the South and will likely always be a major factor in picking hybrids. In the Upper Midwest, it’s an infrequent guest in hybrids under 105-day. Heavy southern rust pressure in 2024 and 2025 will help seed companies get much more accurate readings on individual hybrid tolerances. If you decide to spray, you can have great success preventing southern rust, but you must be timely. It often takes at least two separate applications of fungicide to get you through from tassel until black layer, since fungicides usually last only 2 to 3 weeks.

PICKING HYBRIDS

Each year, corn hybrids enter the market with better yield performance and better disease tolerance. Pick some new hybrids each year, as well as some proven performers for your area.

If Goss’s is your biggest concern, pick hybrids with Goss’s tolerance.

If any of the fungal diseases are your biggest fear, picking hybrids with tolerance is a good idea. Beginning the season with Xyway at planting is advised, and finishing with one or two applications of foliar fungicide is highly recommended.

Finally, plant multiple hybrids and don’t plant any single hybrid on a large percentage of your acres. Spread your risk to avoid a big disaster with any of these diseases.