Paper Abstract
  Transmission and Epidemiology Session

Epidemiology of Phytophthora ramorum in Oregon Forests

E.M. Goheen¹, E.M. Hansen², W. Sutton³, A. Kanaskie⁴, M.G. McWilliams⁴, and N. Osterbauer⁵

Phytophthora ramorum was found in July 2001 near Brookings Oregon, killing tanoak (Lithocarpus densiflorus) and causing dieback of closely associated wild rhododendron and evergreen huckleberry. Recent introduction and an ongoing eradication effort have contributed to the limited disease distribution (about 9 square miles) and forest impact in Oregon. The disease appears to be not only at an earlier stage of epidemic development, but perhaps also following a different trajectory in Oregon than in California. Although nearly all of the dominant vegetation in SW Oregon forests is known to be susceptible, disease remains very limited, with some common hosts in California virtually unaffected in Oregon. In this presentation, we integrate field survey and monitoring observations and isolation results, host range testing, spore trapping data, and emerging information on the population structure of P. ramorum in Oregon to provide a hopeful prognosis for the disease in this state.

---

¹USDA Forest Service, SW Oregon Insect and Disease Service Center, Central Point, OR 97502
²Oregon State University, Dept. Botany and Plant Pathology, Corvallis, OR 97331; (541) 737-5243; hansene@bcc.orst.edu
³Oregon State University, Dept. Botany and Plant Pathology, Corvallis, OR 97331
⁴Oregon Dept. Forestry
⁵Oregon Dept. Agriculture, Salem, OR 97310