**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** DOUGLAS-FIR AND WESTERN HEMLOCK ARE TWO IMPORTANT CROP TREES ON INDUSTRIAL FOREST LANDS IN THE PACIFIC NORTHWEST; THEIR COMMERCIAL VALUE IS ESTIMATED TO BE $20 BILLION DOLLARS ANNUALLY. THE OOMYCETE PHYTOPHTHORA PLUVIALIS IS AN EMERGING PATHOGEN THAT LIKELY IS BOTH ENDEMIC TO THE US AND INTRODUCED TO NEW ZEALAND AND THE UNITED KINGDOM FROM THE US. IT WAS OBSERVED MOST RECENTLY IN THE UNITED KINGDOM ON WESTERN HEMLOCK, WHERE IT NOT ONLY HAS SHIFTED HOSTS, BUT ALSO CAUSES NEW DISEASE SYMPTOMS THAT LEAD TO MORTALITY. THE PD WILL DEVELOP RESOURCES TO INVESTIGATE HOW THE PATHOGEN CAN ADAPT TO NEW HOSTS AND RISKS THAT THE PATHOGEN HAS BOTH IN NATIVE WILDLAND FORESTS AND PLANTATIONS IN THE PACIFIC NORTHWEST. THE SPECIFIC AIMS ARE 1) GENERATE A HIGH-QUALITY REFERENCE GENOME FOR PHYTOPHTHORA PLUVIALIS. 2) TEST IF PATHOGEN POPULATIONS COLLECTED FROM NATIVE WILDLAND FORESTS, DOUGLAS-FIR PLANTATIONS, AND WESTERN HEMLOCK PLANTATIONS ARE GENETICALLY DIFFERENTIATED FROM ONE ANOTHER. 3) TEST IF POPULATIONS ARE DIFFERENTIATED BY HOST PHENOTYPE (DISEASE SEVERITY BY HOST). GENOMIC APPROACHES TO CHARACTERIZE THE POPULATIONS OF PHYTOPHTHORA PLUVIALIS WILL LAY THE GROUNDWORK FOR UNDERSTANDING THE ADAPTATION OF THE PATHOGEN TO NOVEL HOSTS. THE PROJECT WILL ALSO BROADEN THE PD'S TRAINING IN FOREST PATHOLOGY, POPULATION GENOMICS, AND BIOCOMPUTING, WHILE PROVIDING OPPORTUNITIES FOR THE PD TO FURTHER HER MENTORING AND TEACHING SKILLS. THE PROPOSED TRAINING WILL PREPARE THE PD FOR A CAREER AS AN INDEPENDENT RESEARCHER.