Growing wheat means managing disease

Soft red winter wheat is an important rotation crop for Missouri farmers, contributing not only to farm profitability but also to soil health and weed management strategies. The region’s climate, however, creates ideal conditions for foliar and head diseases that can significantly reduce yield, test weight and grain quality if left unmanaged.

Because of the common threat of disease, fungicide applications play a critical role in protecting yield potential and preserving profitability in wheat acres. MFA’s agronomy team compiled the following answers to key questions about wheat management systems, particularly when it comes to disease control:

What’s the wheat disease of greatest concern?

Fusarium head blight (head scab) is typically the greatest concern for wheat growers in MFA territory. This fungus can be borne in seed or soil, which is why MFA highly recommends fungicide seed treatments. However, it can infect flowering wheat heads as well. While flowering, glumes that cover reproductive parts of the flower open to allow for pollination. During this time, rain can splash head scab spores into the glumes, making wheat vulnerable. The flowering pattern of wheat also makes complete control with fungicide difficult. Head scab fungicides are not systemic—they must cover the part of the plant they’re designed to protect.

Growers must apply fungicide during flowering when glumes are open, before infection occurs. Typically, no more than 20% to 30% of the wheat head flowers at one time, providing a three- to five-day window for treatment. Regardless of when you spray, you can’t protect the entire head, but spraying remains valuable—a 30% reduction in head scab still increases yield and grain quality.

How do head scab fungicides help ensure grain quality?

When head scab attacks developing kernels, it leaves behind a shrunken pink berry or an empty glume called a tombstone. Tombstones lower yield, reduce grain quality and often contain high levels of mycotoxin that elevators must screen. Fungicide treatment can not only improve quality and test weight, it can also reduce dockage at the elevator or prevent a load from being rejected.

What other diseases affect Missouri wheat?

Common fungal diseases affecting soft red winter wheat in the state include stripe rust, leaf rust, powdery mildew, tan spot and septoria leaf blotch. Rust can be a major concern because it does most of its damage by attacking leaf tissue, reducing the plant’s ability to photosynthesize energy and convert it to grain. Stripe and leaf rust are fairly easy to control by applying fungicides to wheat before infection becomes severe and after the wheat’s flag leaf emerges. When left uncontrolled, yield losses can be severe.

Weather conditions, disease history and yield potential should all be considered when making fungicide decisions. Fields with high yield potential and a history of disease pressure are often strong candidates for treatment.

Why is application timing so critical?

The flag leaf and head are responsible for a large portion of grain fill in wheat. Diseases that damage these structures late in the season can quickly erode yield potential. A well-timed fungicide application helps protect these yield-driving plant parts, allowing the crop to capitalize on favorable growing conditions.

Research and on-farm experience consistently show that fungicides applied at key growth stages often result in measurable yield advantages, especially when disease pressure is moderate to high. In Missouri, spring weather patterns can shift quickly, and applying fungicides proactively — rather than reactively — is often the best approach to maximize return on investment.

For foliar disease protection, applications made at jointing through flag leaf emergence (Feekes 5–9) can suppress early disease development and protect upper leaf tissue. To manage fusarium head blight, fungicides must be applied at early flowering (Feekes 10.5.1). This narrow application window is crucial because treatments made too early or too late provide significantly less protection. Proper timing, combined with adequate spray coverage, is essential for achieving maximum benefit.

What other management practices are important?

While fungicides are a valuable tool, they should be part of a broader management strategy. Variety selection, crop rotation, residue management and planting date all influence disease risk. MFA agronomists and our Crop-Trak team work with growers to assess individual fields and determine where fungicide applications will provide the greatest economic return.

Controlling insects and weeds helps keep plants healthier, which, in turn, helps ward off disease. We always recommend a seed-applied insecticide in wheat. Aphids and armyworms are the biggest problems. You can control aphids through seed treatment as well as foliarly applied insecticides. Aphids usually do the most damage by infecting wheat with the barley yellow dwarf virus; as few as one aphid per foot of row can cause enough damage to justify treatment. Armyworms move in after moths lay eggs in developing fields and their worms hatch. They also migrate into fields like an invading army—hence their name. Scout for these destructive leaf feeders frequently. If levels are high enough, control them with a foliar insecticide.

Hessian fly infestations can also be a concern, but planting after a killing freeze greatly reduces its likelihood. Resistance traits in wheat can also control a small number of insects on a limited basis.

When it comes to weed control, several herbicides can be effective, depending on the species and timing of application—just like with any other crop. However, fall-applied herbicides in wheat are under-utilized.

What will help get next season’s crop off to the right start?

Our top advice for growing healthy wheat is to start by selecting certified, treated seed designed to tolerate the challenges that you face in your area. Look for seed varieties with high yield potential as well as traits that make the plant resistant to driver diseases. Certified seed also helps ensure all seeds are viable. A lot of farmers save wheat in their bins to plant, but this seed may have a low germination rate, is likely not thoroughly cleaned, and could carry higher levels of seed-borne diseases.

MFA’s agronomy team is committed to helping growers protect their wheat investment. From selecting the right fungicide product to ensuring proper timing and application, we provide local expertise backed by agronomic research and field experience. Reach out to your local manager or agronomist for more information. 

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