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| Symptoms of sudden oak death caused by Phytophthora ramorum on Rhododendron |
Phytophthora ramorum - a guide for Washington nurseries
Sudden oak death (SOD) was first noticed in central California's coastal counties in 1995 and since then large numbers of tanoaks (Lithocarpus densiflorus), coast live oaks (Quercus agrifolia) and black oaks (Quercus kelloggii) have died. The causal organism, the fungus-like Phytophthora ramorum, however, was not named until 2001. There are currently 56 known hosts for P. ramorum falling into two categories: bark canker hosts and foliar hosts. The bark canker hosts are tanoaks and oaks that become infected on the trunks. Foliar hosts are bays, rhododendrons, bigleaf maple, and many others that become infected on the leaves and small branches. While the bark cankers often lead to mortality in tanoaks and oaks, foliar hosts only occassionally die from the P. ramorum infection.
P. ramorum is now known to occur in California, Oregon, Washington and British Columbia. There are two strains (North American and European). In California and southwest Oregon SOD is largely a forest problem. In northern Oregon, Washington and British Columbia, it is a foliar problem on ornamental plants, particularly rhododendrons. We are greatly concerned, however, about the spread and development of SOD in Washington and have developed this web site to keep researchers, extension agents, and the public up to date on the latest information on SOD.
For more information please contact
Dr. Gary Chastagner
WSU Puyallup Research and Extension Center
7612 Pioneer Way E.
Puyallup,
WA 98371-4998
Phone: 253-445-4528
E-mail: chastag@wsu.edu
This
page last modified on
October 18, 2005
