Population Structure of Phytophthora ramorum in Oregon 1 Simone Prospero

Phytophthora ramorum is infecting plants in Oregon forests and nurseries. In this study, we analyzed the population structure of the P. ramorum in Oregon from 2001 to 2004 using microsatellites. The P. ramorum population in Oregon is characterized by low genetic diversity, significant genetic differences between nursery and forest populations, and no evidence of sexual recombination. The forest population is dominated by a single multilocus genotype in all four years, indicating the persistence of pathogen inoculum. In nurseries, identical genotypes were not recovered during both sampling years (2003 and 2004), suggesting pathogen eradication was effective. This research highlights the continued importance of sanitation and quarantine in nursery production to prevent further introduction and spread of P. ramorum.