A revised sudden oak death risk map to facilitate national surveys

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The impact of sudden oak death on Pacific Coast wildlands has received much attention from scientists, popular media, and the public. Disease symptoms were first observed in Marin County, in California, in 1994 on tanoak (Lithocarpus densiflorus) and, in 1995, on coast live oak (Quercus agrifolia) and California black oak (Q. kelloggii) (McPherson and others 2003). The crown foliage of affected trees appeared to die over several weeks, while bleeding cankers appeared on the lower trunks of larger trees (Rizzo and others 2002). During the next several years, sudden oak death reached epidemic levels in central and northern California (Frankel 2008, Garbelotto and others 2003, Rizzo and others 2005), with tree mortality estimated in one study to be three to four times the historic rate for tanoak and two times the historic rate for susceptible oak species (Swiecki and Bernhardt 2002). In 2001, the disease was discovered in Curry County, OR, likely having arrived there 3 or 4 years earlier (Frankel 2008, Goheen and others 2002, Hansen and others 2005). In addition to a now-quarantined portion of Curry County, sudden oak death outbreaks have so far been recorded in fourteen counties in California, extending from Monterey County northward to Humboldt County (Frankel 2008).

  • Citation: Koch, Frank H.; Smith, William D. 2012. A revised sudden oak death risk map to facilitate national surveys. In: Potter, Kevin M.; Conkling, Barbara L., eds. 2012. Forest health monitoring: 2009 national technical report. Gen. Tech. Rep. SRS-167. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 109-136.

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