Surveying for Phytophthora ramorum in Urban and Wild Forests Throughout Western Oregon

N. Osterbauer, A. Trippe, S. Suttle, and M. Boschee, Oregon Department of Agriculture, 635 Capitol St. NE, Salem, OR 97301-2532, (503) 986-4636, and A. Kanaskie and L. Bauer, Oregon Department of Forestry, 2600 State St., Salem, OR 97310, (503) 945-7200; nosterba@oda.state.or.us.

In 2004, Oregon received information indicating Phytophthora ramorum-infected nursery stock may have been shipped to 52 nurseries throughout Western Oregon. The pathogen was detected in nine of the nurseries in seven counties (Clackamas, Josephine, Lane, Lincoln, Marion, Multnomah, and Washington). Because the pathogen may have been present at these nurseries for =12-mo, the urban and wild forests nearby were surveyed. As the P. ramorum-susceptible plants were non-contiguous in these areas, the USFS Sudden Oak Death National Detection Survey for Forests protocol was used to provide a systematic survey strategy. Four transects were established around each nursery and around a tenth nursery (Columbia County) where P. ramorum was found. All susceptible plants within each transect were visually surveyed and samples collected for laboratory testing. Five subsamples per plant were tested with DAS ELISA to identify Phytophthora-infected plants. DNA was extracted from ELISA-positive samples by spin column chromatography and then tested with nested PCR and with multiplex PCR. A total of 782 samples were collected from 40 transects. One sample collected in Marion County tested ELISA-positive. DNA testing showed the Phytophthora infecting the plant was not P. ramorum. Based on these survey results, P. ramorum did not spread from the infected stock within the nurseries into the natural environment in these eight Western Oregon counties.

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