Effectiveness of a novel fungicide pydiflumetofen against Fusarium head blight and mycotoxin accumulation in winter wheat

Fusarium head blight (FHB) causes yield loss, quality reduction, and grain mycotoxin accumulations. A novel pydiflumetofen-containing fungicide, Miravis Ace, was recently registered in North America. The main objective of this study was to assess the efficacies of Miravis Ace and the timing of application alongside industry standard triazole fungicides (Prosaro, Caramba, Proline and Folicur) on suppressing FHB, reducing mycotoxins and improving wheat agronomic performance. The assessment was conducted across six natural environments on commercial farm fields and in two artificially inoculated-misted environments. All environments included 5 fungicides (Miravis Ace and the four triazole fungicides) and 3 application timings (Zadoks GS 59, 65, 69-71). Additionally, for the ZGS 65 timing, the experiment in the natural environment included a quinone outside inhibitor (QoI) fungicide pyraclostrobin (Headline). In general, Miravis Ace tended to be more effective on FHB suppression than the triazole fungicides across all environments. However, any biological differences tended to be statistically non-significant, likely because of a lack of statistical power. Miravis Ace reduced total deoxynivalenol (DON) concentration by 52-73% compared to the non-treated control. If applied at ZGS 59-65, Miravis Ace was more effective in increasing yield and test weight than the triazoles tested. Across fungicides, applications made at ZGS 65 were most effective in FHB suppression compared to earlier or later application timings. There was no evidence that pyraclostrobin increased mycotoxin concentrations. Overall, compared to the triazole fungicides, the novel pydiflumetofen-containing fungicide tended to have lower FHB suppression and mycotoxins, higher grain yield and test weight, and higher harvest moisture, but differences were not always statistically significant. Because the main active ingredient in Miravis Ace has a different mode of action than the triazoles, we speculate that this fungicide will be competitive with industry standards, and benefit strategies for fungicide resistance management.