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Rogue Valley is free of sudden oak death By PAUL FATTIG Plant pathologist Ellen Goheen has relatively good news for Rogue Valley residents worried sick that their ill-looking oak trees may be succumbing to the pathogen known as sudden oak death. The trees are simply reacting to the extended drought, not to the sudden oak death which has been killing trees in Northern California and in the southern corner of coastal Oregon, she said. In the past year, the valley has received only about 50 percent of its normal rainfall. No SOD victims have been found in Oregon's interior valleys. "The oaks in the Rogue Valley are under a great deal of drought-related stress this year," Goheen said. "Their leaves are turning color early. We're also seeing some branch dieback." The bad news is that the local trees aren't out of the woods yet when it comes to SOD, she said. What to look for Sudden oak death attacks the bark of trees, causing cracking and weeping before dying. Trees suffering from SOD often bleed burgundy-red to black sap from their bark, develop sunken or flattened cankers beneath the bleeding and a distinctive dark red canker margin in the bark and wood. The symptoms normally occur from three to 15 feet off the ground. Once infected, trees do not recover. Young tan oaks die within three weeks of the fungal infections, scientists report. "There is a concern about it coming inland," she said. "It would be particularly dangerous if someone brought it into Rogue Valley. "We are very concerned about anyone moving firewood, branches - any kind of material - from the diseased areas," she added. While the disease appears to be spread short distances by water such as rain splashes, human activity could transport it long distances, she said. Goheen was among the scientists who spotted the telltale brown patch of SOD-killed oak trees northeast of Brookings from the air in mid-July. The aerial survey, from the California state line to the mouth of the Rogue River, was part of a larger program that also included ground surveys. Laboratory tests confirmed the pathogen in four tan oak groves near Oregon's southwest coast, including sites from two acres to 11 acres. The infected sites were on nonindustrial private lands, industrial land and on the Coos Bay District of the Bureau of Land Management. "This is a very difficult disease to deal with," said Goheen, who is based at the Forest Service's Southwest Oregon Forest Insect and Disease Technical Center at the J. Herbert Stone Nursery in Central Point. The disease, which scientists call Phytophthora ramorum, causes stem cankers, leaf spotting, branch dieback and death. It prefers cool, moist conditions, Goheen noted. Large numbers of tan oak, coast live oak and California black oak have died from the fungus in Northern California. Up to 80 percent of oak groves in some areas have died. In addition to the oaks, known host plants include Pacific madrone, evergreen huckleberry, myrtlewood and rhododendrons. "We aren't really sure what makes the trees susceptible to this exotic pathogen," Goheen said. "It's new to science." In fact, the pathogen, first discovered in 1995, has only been found in California and a small part of Oregon in the wild, and in landscape horticulture in the Netherlands and Germany. In the latter, it was found in rhododendrons and viburnums. Fortunately, the white oaks tested in California aren't susceptible. Southern Oregon contains groves of California black oak as well as white oak. There are also isolated patches of canyon live oak, a relative of the white oak. In addition to serving as a source of beauty, the oaks also provide valuable wildlife habitat as well as a commercial product. A strict quarantine has been placed in a 9-square-mile area around the four infested sites in Oregon. The Forest Service is working with the BLM, the Oregon Department of Forestry and the Oregon Department of Agriculture in trying to stop the spread of the pathogen. "We continue to actively investigate for it," Goheen said. "In addition to the coast, we are looking throughout the Rogue and Umpqua drainages. "We're hoping it will stay along the coast," she added. For additional information on SOD, check out Web sites www.suddenoakdeath.org and www.fs.fed.us/r6/rogue/swofidsc Reach reporter Paul Fattig at 776-4496 or e-mail him at [email protected] Mail Tribune Home | Ottaway Newspapers, Inc. | Dow Jones & Co., Inc. | Privacy | Contact Us Copyright � 2001 Mail Tribune, Inc.