FUSARIUM WILT CAUSED BY FUSARIUM OXYSPORUM F. SP. VASINFECTUM (FOV) IS AN EMERGING DISEASE THAT THREATENS COTTON PRODUCTION IN THE UNITED STATES. IN THE PROPOSED PROJECT WE ADDRESS THE URGENT NEED TO UNDERSTAND THE EPIDEMIOLOGY OF FOV AT THE AGRICULTURAL SYSTEM LEVEL. THE COTTON-FUSARIUM PATHOSYSTEM INVOLVES INTERRELATED BIOTIC AND ABIOTIC COMPONENTS: A DISEASE AGENT ABLE TO LIVE AS A SAPROPHYTE, ENVIRONMENTAL DETERMINANTS OF INFECTION, AND NEWLY-DISCOVERED BIOTIC INTERACTIONS BETWEEN THE AGENT AND ADDITIONAL MICROBIAL TAXA. INCREASINGLY, THE RECIPROCAL ROLES OF ABIOTIC AND BIOTIC EFFECTS IN MODULATING EACH OTHER IS CLARIFIED THROUGH RESEARCH, ALLOWING COTTON GROWERS TO USE INFORMATION TO DYNAMICALLY MANAGE DISEASES IN EFFICIENT AND SUSTAINABLE WAYS. WE WILL COMBINE IN-FIELD OBSERVATIONAL DATA AND ANALYSIS WITH LABORATORY STUDIES INTO THE MECHANISMS THROUGH WHICH PATHOGENESIS IS MODULATED BY ABIOTIC AND BIOTIC FACTORS SUCH AS NUTRIENT AVAILABILITY IN SOILS, MOISTURE, TEMPERATURE, AND MICROBIOTA, WITH THE GOAL OF UNDERSTANDING FUSARIUM WILT EPIDEMIOLOGY TO PROVIDE ACTIONABLE INFORMATION TO DISEASE MANAGEMENT EFFORTS. WE PURSUE THREE OBJECTIVES: 1) CHARACTERIZE THE ABIOTIC CONDITIONS UNDER WHICH FOV PRESENCE RESULTS IN DISEASE; 2) CHARACTERIZE MICROBIOTA ASSOCIATED WITH DISEASE AND DESCRIBE THEIR INTERACTIONS; AND 3) CHARACTERIZE HOW BIOTIC AND ABIOTIC FACTORS AFFECT COTTON-FOV ASSOCIATIONS, USING FUNGAL ENZYME AND SECONDARY METABOLITE PROFILES AS INDICATORS OF THE ASSOCIATIONS. IN ADDITION TO ADDRESSING THE DIRECT NEED TO ADDRESS FOV, FINDINGS WILL IMPROVE EPIDEMIOLOGICAL UNDERSTANDING OF SOILBORNE PATHOGENS IN GENERAL, AND PROVIDE LINKAGE TO RESEARCH UNDERWAY IN DISCIPLINES WITH FOCUS ON AGRICULTURAL MICROBIAL SYSTEMS AS MEDIATORS OF PLANT DISEASE.