2007 Annual Report 1a.Objectives (from AD-416) To determine the effectiveness of a systems approach for producing nursery stock free of plant pathogenic Phytophthora species and to compare it to the current system by measuring the frequency of infestation by Phytophthora species before and after implementation of the systems approach. 1b.Approach (from AD-416) Symptomatic and asymptomatic plant tissue will be sampled for the presence of Phytophthora. Soilborne Phytophthora will be sampled by removing cores from potting media (container stock) or soil (field-grown plants). Water samples from water sources will be baited with rhododendron leaves. Documents SCA with Oregon State Univ. 4.Accomplishments Phytophthora is the most significant pathogen of nursery crops nationwide. This project is testing a systems approach for producing nursery stock free of Phytophthora. Using the Hazard Analysis Critical Control Point (HACCP) approach developed in the food processing industry, all possible sources of nursery contamination by Phytophthora species are being identified, and specific management strategies to prevent infestation are being developed. Scientists from HCRU Corvallis, OR sampled four nurseries participating in the study 6 times per year to determine Phytophthora species abundance. We found Phytophthora in soil, leafy debris, irrigation water, piles of potting medium, re-used pots, and even tires of delivery trucks. Over 100 Phytophthora isolates have been identified and most belong to one of the following genera: P.ilicis, P. citricola, P. citrophthora, P. cinnamomi, and P. syringae. Results from this project will provide data for the development of Best Management Practices and will provide a basis for considering improvements to the current system of periodic nursery stock inspections. NP303 action plan componentII:Biology, Ecology, Epidemiology, and Spread of Plant Pathogens and Their Relationships with Hosts and Vectors, Problem Statement A Pathogen Biology, Virulence Determinants, and Genetics of the Pathogen. 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 3 Number of newspaper articles and other presentations for non-science audiences 1