** 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 PATHOGENS NEGATIVELY IMPACT AGRICULTURAL, RANGELAND AND FORESTRY PRODUCTIVITY. WHILE MANAGEMENT OF PESTS IN ANNUAL CROPS EMPHASIZES CONTINUED DISRUPTION OF PATHOGEN POPULATIONS, SUCH STRATEGIES HAVE LIMITED VALUE IN PERENNIAL PRODUCTION SYSTEMS. IT IS QUITE LIKELY THAT MORE DURABLE RESISTANCE TO PATHOGENS CAN BE GENERATED BY MIMICKING NATURE AND UTILIZING MIXED STRATEGIES THAT INCLUDE BREEDING FOR RESISTANCE AND PLANTING PERENNIAL CROPS IN MULTISPECIES POLYCULTURES. WE EVALUATE THIS POSSIBILITYAND APPLY THIS FRAMEWORK TO AN EMERGING PERENNIAL OILSEED CROP, THEREBY ILLUSTRATING POTENTIAL RELEVANCE TO OTHER PERENNIAL PRODUCTION SYSTEMS.WE HAVE FOUND THAT PATHOGEN IMPACTS DECLINE WITH SPECIES DIVERSITY IN PLANT COMMUNITIES, AND THAT THIS PATHOGEN DILUTION GENERATES SUBSTANTIAL INCREASES IN PRODUCTIVITY RELATIVE TO MONOCULTURE (I.E. OVERYIELDING). WE ALSO FOUND THAT PATHOGEN DILUTION OCCURS IN CONCERT WITH EVOLUTION OF GENETIC RESISTANCE TO DISEASE. OUR WORK TESTS THE JOINT IMPACTS OF THE GENETIC AND COMMUNITY DIVERSITY ON PLANT PATHOGEN SPREAD AND IMPACT BUT DEVELOPING AND TESTING A MATHEMATICAL FRAMEWORK THAT PREDICTS PATHOGEN DILUTION AND ITS IMPACTS ON PRODUCTIVITY. WE BUILD MORE SYNTHETIC UNDERSTANDINGOF THE ECOLOGICAL AND GENETIC CONTROLS OF PATHOGEN SPREAD, WHICH TOGETHERCAN ADVANCE PEST MANAGEMENT IN AGRICULTURE AND RANGELANDS. WE WILL ALSO TRAIN STUDENTS AND HIGH SCHOOL TEACHERS IN AGROECOLOGY, PLANT PATHOLOGY AND DISEASE ECOLOGY.