In spring of 2004, WSU initiated a research project to examine factors influencing P. ramorum infection in Christmas tree plantations with funding provided by a two-year USDA Forest Service grant. Work on this project is occurring at the Black Road Christmas Tree Farm near Los Gatos, CA. This is a 23-acre U-cut Christmas tree farm that was established in 1966. Conifers being grown at this site include Douglas-fir, grand fir, giant sequoia, scotch pine, white fir, and California red fir. Some known P. ramorum hosts in the forest adjacent to the edge of the farm include:
California bay laurel, madrone, big leaf maple, toyon, coast redwood, and tanoak. Dieback on some of the grand and Douglas-fir along the interface between the infected forest and the Christmas tree farm appears to have occurred at least 4 years previously, in 2000. During 2005, conditions were very favorable for disease development. Results from this study indicate that most of the infected Christmas trees occurred within 2 meters of the edge of the P. ramorum-infected bay laurel forest canopy. Virtually no infection was evident on Christmas trees that were >5 meters away from the forest edge.
Given recent developments in the UK, where P. ramorum is infecting conifers, further research at WSU-P is being done on the susceptibility of conifer species in western Washington forests.
In Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. 2013. Proceedings of the Sudden Oak Death Fifth Science Symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 169 p.
Symptoms Associated with Inoculation of Stems on Living Douglas-fir and Grand Fir Trees with Phytophthora ramorum 15 KB
Gary Chastagner, Kathy Riley, Katie Coats, Marianne Elliott, Annie DeBauw, and Norm Dart.
In Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M. 2010. Proceedings of the Sudden Oak Death Fourth Science Symposium. Gen. Tech. Rep. PSW-GTR-229. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 378 p.
Chastagner, G.A., E.M. Hansen, K.L. Riley, and W. Sutton. 2005. Susceptibility of conifer shoots to infection by Phytophthora ramorum. Sudden Oak Death Science Symposium II, 18-21 January 2005, Monterey, CA.
Chastagner, G.A., K.L. Riley, E.M. Hansen, and W. Sutton. 2004. Christmas tree and conifer nursery stock: Sudden oak death project update. Christmas Tree Lookout 37(3): 10-13.
Chastagner, G.A., E.M. Hansen, K.L. Riley, and W. Sutton. 2004. Susceptibility of conifer shoots to infection by Phytophthora ramorum. Phytopathology 94: S16.
Chastagner, G.A., E.M. Hansen, K.L. Riley, and W. Sutton. 2003. Susceptibility of conifer shoots to infection by Phytophthora ramorum. In: Program and abstract book, sixth international Christmas tree research and extension conference; 2003 Sept. 14-19; Hendersonville, NC; 10-11.