Thanks to warming temperatures, the current head scab risk is low to medium for wheat flowering today and later this week (Figure 1). The exception is Ashtabula County and northeastern Trumbull County that have a high risk for susceptible wheat varieties currently flowering.
These risk estimates were generated by The Fusarium Risk Tool available at https://www.wheatscab.psu.edu/. This tool uses temperature, rainfall, and relative humidity to estimate the risk of infection by Fusarium graminearum that causes Fusarium head blight or head scab in wheat. The fungus also produces the mycotoxin deoxynivalenol (DON) or vomitoxin. Keep in mind, the estimate shown in the map is applicable to fields flowering today if a susceptible variety is planted. You should check the tool periodically as more fields begin to flower to see if the risk changes.
Fungicide applications to reduce head scab development and DON contamination should be made at early flowering (Feekes 10.5.1) when yellow anthers are seen at the center of the wheat spike (Figure 2). (Wheat flowering stage video: https://www.youtube.com/watch?v=pEJrX6UqF_E&list=PLYlh_BdeqniJ8oD8TnyGhQHRd96ptV0Yt&index=5) However, applications delayed 4 days after initial flowering can still suppress head scab and DON. Be sure to select a triazole-based fungicide and follow all product label instructions.
Fungicides with a ‘good’ efficacy rating based on multi-state fungicide trials, include Proline 480 SC, Prosaro 421 SC, Sphaerex, Miravis Ace SE, and Prosaro Pro SC. Access the complete wheat fungicide efficacy chart provided by the Crop Protection Network at https://cropprotectionnetwork.org/publications/fungicide-efficacy-for-control-of-wheat-diseases.
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