Strawberry gray mold is a devastating disease that drives fungicide spray programs across all growing regions worldwide. A recently discovered fungal speciesBotrytis fragariae, along withB. cinerea,have been frequently found to cause gray mold in the southeastern strawberry fields. Fludioxonil, belonging to phenylpyrroles, is a key fungicide for gray mold control. While little resistance to fludioxonil was found inB. cinerea, concerning levels of resistance was detected inB. fragariae. Given the apparent importance of gray mold in strawberry production, we aim to better inform farmers about the risk and optimum fungicide control of strawberry gray mold, and build a solid foundation for future collaborative work to more effectively tackleB. fragariae, ultimately contributing to improving sustainability and profitability of strawberry production in the U.S.This project has three specific objectives: 1) Investigate prevalence and fungicide resistance profiles ofB. fragariaefrom California and northeastern strawberry fields; 2) Determine intraspecific variation and population structure ofB. fragariaevia whole-genome resequencing; and 3) Explore molecular basis of resistance to the fungicide fludioxonil in the U.S.B. fragariaeisolates.