Geographic distribution and diversity of Phytophthora spp. associated with bleeding cankers of European beech, Fagus sylvatica

European beech (Fagus sylvatica) are common in managed landscapes throughout the northeastern United States. The death of mature specimens has been reported for at least 50 years, although a cause has not been determined. Often, the first indication of decline is the presence of bleeding cankers on the lower trunk. Surveys have revealed cankers are widespread, affecting about 25% of mature European beech in the Northeast. These symptoms, along with ELISA results and literature reports, suggested the involvement of a species of Phytophthora. Attempts to isolate from the cankers consistently yielded two members of the genus Phytophthora; P. citricola and P. cactorum. Identification of isolates was conducted using morphological characteristics as well as phylogenetic analyses comparing the beta tubulin and cytochrome c oxidase genes and the ITS regions. Both species were found associated with diseased trees throughout the Northeast, often infecting trees at the same site, though they were never recovered from the same tree. Current work is focused on completing Koch's postulates with both species.