**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** PLANT DISEASES ARE A CRITICAL THREAT TO AGRICULTURE WORLDWIDE, AND FUNGICIDES ARE A VALUABLE TOOL FOR DISEASE PREVENTION. DUE TO WIDESPREAD USE OF FUNGICIDES, PLANT PATHOGEN POPULATIONS, INCLUDING THE HIGHLY DESTRUCTIVE PATHOGEN BOTRYTIS CINEREA, ARE BECOMING RESISTANT TO THE AVAILABLE FUNGICIDES. WHEN PATHOGENS BECOME RESISTANT TO A FUNGICIDE, THEY MAY BE LESS COMPETITIVE AND AGGRESSIVE THAN THEY WOULD BE IF THEY WERE SENSITIVE TO THE FUNGICIDE, WHICH IS CALLED A FITNESS COST. THE FITNESS COSTS ASSOCIATED WITH RESISTANCE TO THE MOST IMPORTANT FUNGICIDES ARE NOT FULLY UNDERSTOOD, LEADING TO CHALLENGES IN PROVIDING ACCURATE GUIDANCE ON MANAGING FUNGICIDE RESISTANCE.THIS PROJECT AIMS TO CLARIFY THE SIGNIFICANCE OF FITNESS COSTS ASSOCIATED WITH RESISTANCE TO THREE FREQUENTLY RELIED UPON FUNGICIDE GROUPS. GENE EDITING TOOLS SUCH AS CRISPR/CAS9 AND MITOCHONDRIA-TARGETING NUCLEASES WILL BE UTILIZED TO INDUCE TARGETED GENETIC MUTATIONS THAT ARE KNOWN TO CAUSE FUNGICIDE RESISTANCE INTO B. CINEREA. THEN, LABORATORY EVALUATIONS OF THE FITNESS OF THESE FUNGICIDE-SENSITIVE AND FUNGICIDE-RESISTANT STRAINS WILL BE CONDUCTED. THIS PROJECT IS INVESTIGATING FITNESS COSTS IN A NEW WAY USING THESE GENE EDITING TOOLS, AND MAY PROVIDE A CLEARER PICTURE OF FITNESS COSTS. RESULTS FROM THIS PROJECT WILL HELP TO INFORM GROWER FUNGICIDE CHOICES AND FUNGICIDE RESISTANCE MANAGEMENT STRATEGIES. IN THE LONG-TERM, THIS COULD RESULT IN PROLONGED OR RENEWED EFFECTIVE USE OF THESE VALUABLE DISEASE CONTROL TOOLS.