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POSTERS: Chemical control

Sensitivity of Fusarium graminearum in Michigan to fungicide pydiflumetofen, a component of Miravis formulations.
Mikaela Breunig - Michigan State University. Martin Chilvers- Michigan State University

In North America, Fusarium species including F. graminearum are a major concern due to mycotoxin contamination of wheat grain. Historically triazole products have been the sole option to manage head scab in wheat. Recently a new SDHI active ingredient, pydiflumetofen (AdepidynTM, Syngenta), received registration in the U.S. and will be marketed in the 2019 growing season as Miravis Ace for head scab control. We investigated the in-vitro sensitivity and determined baseline sensitivity of Michigan populations of Fusarium graminearum to the new chemistry pydiflumetofen. Isolates were collected as part of a survey of Michigan wheat and corn to determine the Fusarium species present and fungicide sensitivity of the population. Sensitivity was determined by mycelial growth assays for 97 isolates, and spore germination assays conducted on a subset of 22 isolates. Effective concentration that reduced pathogen by 50% (EC50 ) and 90% (EC90 ) were calculated. EC50 values from spore germination (mean 0.30 µg/ml) were significantly greater than EC50 values from mycelial growth (mean 0.069 µg/ml), however EC90 values for spore germination were significantly lower than mycelial growth values. We found isolates less sensitive to triazoles (EC50 from 1-4 µg/ml) were still quite sensitive to pydiflumetofen (<0.1 µg/ml). These studies provide us with phenotypic data that can be used as a baseline for future monitoring and indicate F. graminearum populations in Michigan are very sensitive to the new chemistry pydiflumetofen in-vitro.