A New Report of Phytophthora ramorum on Rhamnus purshiana in Northern California

Vettraino, A.M., Hüberli, D., Swain, S., Smith, A. and Garbelotto, M. (2006) A New Report of Phytophthora ramorum on Rhamnus purshiana in Northern California. Plant Disease, 90 (2). p. 246.

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Abstract

Rhamnus purshiana, or cascara, is a deciduous tall shrub or small tree as much as 9 m high with thin, smooth, silver-gray bark. It is often present in shady sites in redwood and mixed evergreen forests of the North Ameri-can west coast, from British Columbia to northern California. In July 2005, symptomatic leaves with irregular, black spots, 2 to 5 mm in diameter and concentrated toward the tips, were collected from four cascara plants in the Samuel P. Taylor State Park, Marin County, California. There was no evidence of defoliation.