California's oaks are an essential part of our heritage and natural landscape. Since 1995, SOD has been confirmed in California from Humboldt County to Monterey County, as well as in Curry County, Oregon, and is particularly severe in Marin, Santa Cruz, and Monterey Counties in California. The actual current geographic range of the fungus that causes SOD, Phytophthora ramorum, is unknown. A team of USDA Forest Service, California State University (CSU), and University of California (UC) researchers was assembled to conduct a statewide survey to map and identify the fronts of infection and overall distribution of SOD on overstory hosts, including coast live oak (Quercus agrifolia), tanoak (Lithocarpus densiflorus), Shreve oak (Quercus parvula var shrevii), and California black oak (Quercus kelloggii). The twelve currently infested counties plus those counties south of San Francisco (San Benito, Fresno, San Luis Obispo, Kern, Santa Barbara, Ventura, and Los Angeles), and the Sierra Nevada foothill band of black oak were jointly surveyed. Additional counties bordering infested counties including Solano, Yolo, Lake, Glenn, Tehama, Trinity and Siskiyou were also surveyed. Aerial surveys were conducted from May 29, 2002 through July 3, 2002 over 20 million acres of species susceptible to SOD. Approximately 14,000 miles of ground were flown and 450 polygons exhibiting oak mortality mapped. The area included in the polygons was approximately 157,000 acres, a nearly four-fold increase in the area mapped in the 2001 aerial survey. Ground surveys of a prioritized sample of the aerially surveyed polygons were checked primarily for new infestations and for infestations that expand the existing range of SOD. Field crews were provided with GPS coordinates to center points of a polygon, navigated to the center and determined if SOD symptoms were present in any one of the susceptible species. Established sampling protocols were followed and all samples were shipped to the laboratory for confirmation of SOD. Results from the entire aerial and ground survey were compiled and evaluated
