EARLY SEASON FUNGICIDE ON WHEAT
Information for this article was written by Andrew Friskop from NDSU Extension Plant Pathology. The complete article is located at https://bit.ly/4vm5mHP.
Cereal crops residue-borne diseases such as tan spot and Stagonospora nodorum blotch (SNB) are the primary targets for early-season fungicide application. Tan spot is more common than SNB in North Dakota (ND), but both diseases have shown a downward trend in prevalence in ND wheat fields over the past eight years. This can be largely attributed to the use of management tools such as crop rotation (has been shown to reduce tan spot by 70%), genetic resistance (average resistance in 2026 is better than average resistance in the 1990s), residue management (disrupts longevity of the pathogen), and regular use of fungicides
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in wheat crops (tillering, flag leaf, and/or early-flowering). The greatest risk for tan spot and SNB will be in no-till production regions, with a short rotation away from wheat, and during springs with excessive leaf wetness during the growing season. At this point in the growing season early prediction risk for tan spot and SNB in North Dakota is “low”. There are several efficacious products that can be used for tan spot and SNB. This includes products with active ingredients belonging to the mode of action groups 3, 7 and 11. Remember, fungicides applied at tillering will only protect the available leaves at time of application. Any new leaves that emerge should be considered as being left unprotected due to the limited effective mobility of fungicides.
One way to capture the answer to the yield response question is to dive deeper into the data generated by NDSU Extension – Cereal Crop Plant Pathology. Dr. Friskop has continually updated a data set to estimate yield response from an early season fungicide reflective of disease risk. This data set now includes field research conducted from 2008 to 2025 with over 125 replicated data points on the tillering fungicide application. All fungicides with a very good to excellent rating on tan spot and/or SNB were combined for each disease risk scenario. The primary driving factor for determining disease risk was previous crop. Wheat following wheat would indicate a moderate to high disease risk scenario. Wheat following a broadleaf would be a very low to low disease risk scenario. The second driving factor for disease risk was environment (i.e., prolonged leaf wetness and cool-wet weather in late-May into early-June would increase risk). The data suggests yield responses ranged from 0.0002% to 1.7% for very low to low disease risk, and 4.1% to 4.3% for moderate and high disease risk scenarios. To better apply these values, let’s assume a farm average for a wheat field is 60 bu/A. If you seed wheat after a previous broadleaf crop, an early season fungicide may provide a response of 0.01 to 1.02 bushels. However, if you are in a wheat-on-wheat production system, the estimated yield response will be approximately 2.5 bu/A.
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