Challenges and Opportunities in Small Grain Harvest 2025

My Wheat Looked Great at the Beginning of the Month—what happened?

Reports from the field reveal that wheat and barley that once looked clean and healthy in the first week of June are now showing signs of disease and quality issues. The persistent wet and cool conditions in most of Pennsylvania over the past few weeks have brought rust and leaf spots, powdery mildew, and other head infections such as scab, blotches, and sooty mold. If you have not had the opportunity to walk your fields recently, now is a good time to evaluate late season diseases in your crops. The information you gather will be critical to some harvest decisions.

Why do my Head Scab-treated Fields have less Leaf Disease?

Many have observed that wheat treated for Fusarium head blight (scab) at flowering was also better protected against flag leaf diseases than unsprayed fields. Even if the target of our sprays is scab, we typically benefit from these fungicide treatments in the reduction of other disease-causing fungi as we approach harvest.

Why is the barley in better shape than the wheat?

Others note that barley seems to have fared better than wheat crops in terms of scab. While barley is vulnerable to infection by Fusarium graminearum at flowering, barley has a natural genetic resistance called "Type II resistance" that prevents some of the additional spread of the fungus throughout the head from the initial infection site ¹. This means that while infections were spreading to new kernels within wheat heads, barley heads maintained their initial level of infection.

What could I have done to prevent this?

It is important to recognize that because of the way fungi like those that cause head scab gain entry and spread in the plant, and the constraints imposed by post-harvest spray intervals and economics, it is impossible to prevent all disease. Even with moderately resistant varieties and well-timed fungicide applications, 100% protection against FHB cannot be achieved when weather conditions are highly conducive to disease development.

What should I do now?

Now we have the opportunity to limit further impact of these diseases on yield and quality by making some choices approaching harvest. Waiting for the crop to reach the ideal storage moisture in the field can result in additional chances for disease to spread and mycotoxins to develop. Quick harvest and immediate cooling and drying will not reverse the damage, but will stop the progress in its tracks and keep things from getting worse. Ideally, getting the grain below 15% moisture (13% for long-term storage) and 50 degrees F will halt the deterioration.

For any fields in which 25% of heads or more are infected with scab, mitigation efforts can be applied. First, contact your insurance company to determine if mycotoxin testing or a claim is in order. The decision and any necessary testing need to be done before harvest begins. Once you begin harvest, consider segregating the grain from these fields to preserve the quality of the grain from unaffected fields.

When harvesting, specific adjustments can be made to your equipment to help "clean" the grain as it moves through the combine. Since diseased kernels are lighter than healthy ones, using combine settings to blow more of the low-quality grain back onto the field will result in a higher percentage of good grain in your hopper. A recent edition of FHB Tool Talk from the U.S. Wheat and Barley Scab Initiative provides an overview of a study that identified optimal combine fan speeds and shutter openings to minimize price discounts and maximize profits when harvesting scabby wheat.

What About Next Year?

For fields highly affected by scab this year, it is best to avoid rotating into corn or a grassy forage in 2026, especially where no-till systems maintain abundant crop residue. Moving these fields into a broadleaf crop like soybeans or alfalfa is a good option to prevent inoculum carry-over that could increase the risk of mycotoxin-causing infections in corn, for instance.

As you consider small grains for planting this fall, be sure to research varieties that offer moderate resistance to scab and other diseases as well as good agronomic properties. Genetic resistance combined with proper fungicide applications at flag leaf and flowering is a multi-pronged strategy for excellent grain quality when weather conditions are conducive for disease development.

References:

1. Jansen, C., von Wettstein, D., Schäfer, W., Kogel, K., Felk, A., and Maier, F.  Infection patterns in barley and wheat spikes inoculated with wild-type and trichodiene synthase gene disrupted Fusarium graminearum. doi/10.1073/pnas.0508467102