U.S. LEAFY GREEN PRODUCTION IS IN CRITICAL NEED OF IMPROVED FOOD SAFETY SYSTEMS. EFFORTS TO IMPROVE LEAFY GREEN SAFETY INCLUDE A FOCUS ON PREVENTION OF CONTAMINATION IN PRIMARY PRODUCTION. UNFORTUNATELY CURRENT APPROACHES TO PREHARVEST DETECTION OF PATHOGENS THROUGH COMPOSITING PHYSICAL GRAB SAMPLES IS SEVERELY UNDERPOWERED TO ENSURE FOOD SAFETY OBJECTIVES. THE LONG TERM GOAL OF THIS PROJECT IS TO IMPROVE THE POWER OF PREHARVEST FOOD SAFETY TESTING SO IT CAN BE A MORE RELIABLE RISK MANAGEMENT STRATEGY. THE OVERALL OBJECTIVE OF THIS PROPOSAL IS TO DEVELOP A MORE POWERFUL METHOD TO TEST PRODUCE IN FIELDS FOR PATHOGENS. THE METHOD WILL INVOLVE SWABBING MANY PLANTS IN A PRODUCTION FIELD TO CAPTURE POTENTIAL PATHOGENS ON THOSE MANY PLANTS, AND THEN PASS THAT SWAB TO A SINGLE MICROBIOLOGICAL TEST. THIS METHOD IS CALLED AGGREGATIVE SWAB SAMPLING BECAUSE THE SWAB AGGREGATES PARTICLES FROM MANY INDIVIDUAL PLANTS. OUR SPECIFIC OBJECTIVES WILL INVOLVE FIRST DEVELOPING AND VALIDATING THIS METHOD USING INOCULATED FIELD-TRIAL EXPERIMENTS ATUNIVERSITY FIELD STATIONS. THEN, THE PROJECT WILL TEST THIS METHOD IN COMMERCIAL FIELDS. THE MAJOR IMPACT IS TO ENABLE POWERFUL PREHARVEST AGGREGATIVE SAMPLING THAT COULD EFFICIENTLY IDENTIFY PATHOGENS IN LEAFY GREENS BEFORE THEY ARE HARVESTED AND ENTER THE FOOD SUPPLY.