An unknown species of tree fungus has been identified as the primary reason tens of thousands of oak trees have been dying in the hills and valleys of California's scenic central coast.
The deadly microbe is so new it doesn't even have a name. It was detected by David Rizzo, a plant pathologist from the University of California, Davis. "We've got something that is very different from anything that's been found before," Rizzo said at an early August press conference north of San Francisco in Marin County, where about 40 percent of the oak forest is infected. Rizzo said the fungus is from the same family as the organism that caused the Irish potato famine in the 1840s.
The disease, which has been dubbed Sudden Oak Death, started out in tanoak, but has spread to the more prized coast live oak and black oak trees. The deaths have been concentrated along a 200- to 300-mile front stretching from Big Sur to Mendocino County. Marin County has been hit so hard that officials there declared a state of emergency earlier this year.
State agriculture officials are considering placing a quarantine on wood and soil from infected areas. There is a particular concern that oak firewood will be transported to elsewhere in the state, such as to communities in the Sierra Nevada range, where the oaks have so far been unaffected.
At this point, however, no one knows how the pathogen spreads, which makes quarantining the disease difficult.
The first sign of the disease is wilting branches followed by fading leaves and then the oozing of a black substance from the trunks. An odor resembling fermenting alcohol sometimes comes from the roots. Then large numbers of tiny beetles appear on the bark and begin boring inward. Within months, even weeks, the tree is dead.
Forest Magazine, a publication of Forest Service Employees for Environmental Ethics, September-October 2000.
