While bleeding canker of European beech trees (Fagus sylvatica) has long been recognized as a problem in Europe and North America, the cause in the northeastern United States has not been clear. To resolve this, we surveyed for disease prevalence on European beech, identified the pathogens involved, proved their pathogenicity, compared protocols for pathogen detection, and conducted a soil assay to determine pathogen presence in soil surrounding established trees in residential and commercial landscapes in New York, Pennsylvania, Maryland, Connecticut and Massachusetts. Approximately 40% of surveyed trees had bleeding cankers. While Phytophthora cactorum, P. gonapodyides, P. cambivora and two newly described species, P. citricola I and P. plurivora, were recovered from symptomatic tissue, P. citricola I and P. cactorum were most prevalent. All caused disease when artificially inoculated into European beech sapling stems, although P. cambivora and P. gonapodyides produced significantly smaller lesions. Recovery of the pathogen from symptomatic tissue using selective media, the preferred method of diagnosis, was significantly higher in the fall. ELISA detection was more successful and worked regardless of season, but did not allow identification to the species level. All five Phytophthora species were found in soil surveys; P. cambivora was most common, followed by P. cactorum and P. citricola I. These results provide a foundation for building management strategies to protect valuable specimens of European beech.

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Author notes

We would like to thank the Cooperative Extension educators, tree care professionals, and grounds crew personnel who assisted us in locating and sampling from the trees in this study, specifically Richard Anacker, Dave Barnett, Keith Bernard, Bob Beyfuss, Dave Chinnery, Julie Coop, John DelRosso, Brian Eshenaur, Tom Golon, Jon Hickey, Bob McMullin, Brian Sayers, Chuck Schmitt, Casey Sclar, Vincent Simeone, Jacob Thomas, Paul Walker, Rex Webber and Robert Wick. Funding for this project was provided in part by Almstead Tree Co. of New Rochelle, NY, the New York State Arborists Association, the American Wildlife Conservation Foundation, and the Cornell University Agricultural Experiment Station federal formula funds, Project No. NYC-1536413 received from Cooperative State Research, Education and Extension Service, U.S. Department of Agriculture.

2Former Graduate Student. ahn3@cornell.edu.

3Research Plant Pathologist, 3420 NW Orchard Avenue, USDA-ARS, Corvallis, OR 97330.

4Professor and Chair. gwh2@cornell.edu.