Wheat Disease Update – May 8, 2025
Categories: Disease updates
Meriem Aoun, Small Grains Pathologist
Department of Entomology & Plant Pathology Oklahoma State University
According to the Fusarium Head Blight (FHB) risk tool (wheatscab.psu.edu), there is currently a high risk of FHB across most of Oklahoma, with the exception of the Panhandle (Figure 1). This elevated risk is largely due to recent wet weather and high relative humidity conditions that are favorable for FHB infection during the wheat flowering stage. In eastern Oklahoma, where wheat is often planted following corn, the risk is particularly high due to the presence of Fusarium inoculum in the fields. In contrast, in western Oklahoma, where corn production is not common, we lack information on the presence of Fusarium inoculum, making it difficult to accurately assess the FHB risk in those areas.
Figure 1. Fusarium head blight risk as of 8 May 2025 (wheatscab.psu.edu). Warmer red color corresponds to higher disease risk.
On May 7, a wheat grower in Kingfisher reported a very low incidence of FHB in his field (Figure 2). For wheat fields that have already passed the flowering stage, fungicides cannot be applied. For fields that have not yet reached flowering, the most effective window for fungicide application is at early flowering. Applications made earlier, such as at the heading stage, do not provide effective control of FHB. It is essential to carefully follow all fungicide label instructions to ensure proper use.
Figure 2. Fusarium head blight infection in a grower field in Kingfisher (7 May 2025).
Fungicide products that offer good protection against FHB include Prosaro, Prosaro Pro, and Miravis Ace. While some growers have expressed concerns about the high cost of these treatments, an alternative is Tebuconazole, which is more cost-effective and provides fair efficacy in managing FHB. Wheat fields intended for seed production should be prioritized for fungicide application to preserve seed quality and germination rates, and to help reduce costs related to seed cleaning.