Development of Phytophthora ramorum infection and disease symptoms on coast redwood seedlings

Abstract

Coast redwood (Sequoia sempervirens) is a host for Phytophthora ramorum but it is not clear if the pathogen represents a significant disease risk to this tree species. In an on-going field experiment, we are examining the process of infection and the development of symptoms on coast edwood seedlings in naturally infested sites in southern Humboldt County, California. In November 2006, healthy, potted redwood seedlings were placed mid tanoak and bay trees naturally infected with P. ramorum. Symptoms and disease incidence are being observed periodically, and every two months, a subset of redwood seedlings is destructively sampled to investigate the location and extent of tissue colonization by P. ramorum. To assess inoculum levels to which seedlings are exposed, and to correlate this with disease development, rainwater is being collected for quantification of P. ramorum propagules. Results of this study will help evaluate the risk of P. ramorum to coast redwood seedlings and inform land managers of the potential for reforestation of infested sites with this species.

Parent Publication

• Proceedings of the sudden oak death third science symposium

Citation

Lucas, Sunny; Parke, Jennifer L.; Valachovic, Yana. 2008. Development of Phytophthora ramorum infection and disease symptoms on coast redwood seedlings. 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. p. 397