Stream monitoring for detection of Phytophthora ramorum in Oregon

Abstract

Stream monitoring using leaf baits for early detection of P. ramorum is an important part of the Oregon sudden oak death program. About 50 streams in and near the Oregon quarantine area in the southwest corner of the state are currently monitored. Rhododendron and tanoak leaf baits in mesh bags are exchanged every two weeks throughout the year. Leaves are sent to Corvallis for isolation and PCR diagnosis using the Winton and Hansen ITS primers. P. ramorum is regularly recovered from streams draining infested sites 5 years after eradication treatment. Because there has been a very good correspondence between culture results and PCR results rom these known infested streams, we have changed to PCR only diagnosis on streams outside the known diseased area. If a PCR positive result is obtained, these baits and subsequent baits from that stream are cultured as well as assayed by PCR. In three watersheds Phytophthora ramorum was first detected using stream baiting. Follow up intensive ground surveys located infected tanoaks or other host plants. Phytophthora ramorum has been cultured from one additional stream but a source of inoculum has not yet been found.

Parent Publication

• Proceedings of the sudden oak death third science symposium

Citation

Sutton, W.; Hansen, E.M.; Reeser, P.; Kanaskie, A. 2008. Stream monitoring for detection of Phytophthora ramorum in Oregon. In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 467-470