** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** ORGANIC TREE FRUIT PRODUCTION (APPLES, CHERRIES, PEACHES)EAST OF THE MISSISSIPPI RIVER WILL NOT BE SUSTAINABLE WITHOUT EFFECTIVE MANAGEMENT OF THE BACTERIAL DISEASES FIRE BLIGHT, BACTERIAL CANKER, AND BACTERIAL SPOT. BACTERIOPHAGES (PHAGES) REPRESENT A PROMISING TOOL FOR THE MANAGEMENT OF BACTERIAL PLANT DISEASES; HOWEVER, PHAGES HAVE NOT BEEN DEVELOPED COMMERCIALLY MAINLY DUE TO REDUCED AND INCONSISTENT EFFICACY. WE INTEND TO INTENSIVELY INVESTIGATE THE PHAGE:PATHOGEN DYNAMICS ON APPLE AND CHERRY FLOWERS WITHERWINIA AMYLOVORA(FIRE BLIGHT, APPLE)PSEUDOMONAS SYRINGAE(BACTERIAL CANKER, CHERRY). WE PREDICT THAT THE INCREASED PRECISION IN UNDERSTANDING THESE SYSTEMS WILL ENABLE US TO MORE EFFECTIVELY AND EFFICIENTLY EMPLOY PHAGES IN ORGANIC ORCHARDS. WE WILL ALSO INVESTIGATE MATERIALS THAT CAN DISRUPT CELLULAR AGGREGATES ON PLANT SURFACES, AND MIXING-PARTNER MATERIALS THAT CAN WEAKEN OR KILL A SUBSET OF TARGET CELLS TO AID IN INCREASING THE EFFICACY AND RELIABILITY OF PHAGES. WE WILL CONDUCT YEARLY FIELD TESTING OF PROMISING MATERIALS ON APPLE, CHERRY, AND PEACH. EXTENSION ACTIVITIES WILL INCLUDE DEVELOPING A BIOPESTICIDE SELECTION TOOL FOR THE THREE TREE FRUIT DISEASES STUDIED, PRODUCING A VIDEO TO DEMONSTRATE THE MODE OF ACTION OF PHAGES, AND REPORTING PROJECT FINDINGS TO GROWERS AT THROUGH LOCAL AND REGIONAL FRUIT SCHOOLS, WEBINARS, AND FIELD DAYS.