SOYBEANS ARE AMONG THE MOST VALUABLE AGRICULTURAL COMMODITIES PRODUCED IN THE UNITED STATES (US). IN 2020, MORE THAN 4.1 BILLION BUSHELS OF SOYBEANS WERE HARVESTED FROM OVER 82 MILLION ACRES AT A VALUE OF ~$46.1 BILLION (USDA-NASS 2020). CERCOSPORA LEAF BLIGHT (CLB), PREDOMINATELY CAUSED BYCERCOSPORACF.FLAGELLARIS,ACCOUNTED FOR AN AVERAGE OF 20.2% OF ALL YIELD LOSSES ATTRIBUTED TO FUNGAL DISEASES ACROSS 16 STATES IN THE SOUTHERN US IN 2020, RANKING AS THE MOST IMPORTANT FUNGAL DISEASE IN THE SOUTHERN UNITED STATES. IN TERMS OF PRODUCTION VALUE, LOUISIANA EXPERIENCED THE GREATEST IMPACT FROM CLB WITH A TOTAL ESTIMATED ECONOMIC LOSS OF APPROXIMATELY $17.7 MILLION.OUR PRELIMINARY DATA HAS SUGGESTED THAT A WEEDY ALTERNATIVE HOST, PHYTOLACCAAMERICANA, MAY HARBOR DISCRETE POPULATIONS OF C. CF. FLAGELLARIS AND ACT AS AN INOCULUM RESERVOIR. THE POTENTIAL OF P. AMERICANA TO CONTRIBUTE TO DISEASE IN SOYBEAN FIELDS HAS YET TO BE EXPLORED. ADDITIONALLY, LITTLE IS CURRENTLY KNOWN ON THE GENETIC BASIS FOR ADAPTATION TO SPECIFIC SOYBEAN GENOTYPES OR ALTERNATIVE HOSTS.THIS PROPOSAL AIMS TO COLLECT PROPERLY SAMPLED PATHOGENPOPULATIONS, GENERATE WHOLE-GENOME SEQUENCES, AND PRODUCE ANNOTATEDREFERENCE GENOMESWHICH CAN BE UTILIZED TO ADDRESS THE DISPERSAL CAPABILITIES AND REPRODUCTIVE CAPACITY OF C. CF. FLAGELLARIS, AS WELL AS ITS POTENTIAL FOR ADAPTATION ON SOYBEAN AND ALTERNATIVE HOSTS. ADDITIONALLY, TRANSCRIPTOMIC ANALYSES WILL BE USED TO IDENTIFY GENES AND/OR PATHWAYS INVOLVED IN INFECTION OF SOYBEAN. UNDERSTANDING THE GENETIC BASIS OF ADAPTATION AND MECHANISMS OF INFECTION WILL ENABLE THE DEVELOPMENT OF ROBUST MANAGEMENT PRACTICES THAT ENCOMPASS HOST RESISTANCE, WEED MANAGEMENT, AND FUNGICIDE APPLICATIONS TO PROVIDE A DURABLE STRATEGY FOR DISEASE CONTROL.