Fighting to keep trees alive
BROOKINGS — As early detection systems go, it doesn't look like much.
There are no bells or whistles, only two rhododendron and two tanoak leaves in a mesh bag bobbing in the stream at water site No. 65. The bag is attached by a fishing line to a metal pole with an orange ribbon tied on top.
"It's very low tech but with these, we have been able to find infected creeks early enough so that the infected centers upstream are still very small — sometimes only one or two tanoaks," observed Ellen Goheen as she pulled the bag out of the stream tumbling out of the Rogue River-Siskiyou National Forest a few miles east of Brookings.
Goheen is a plant pathologist who spends much of her time battling Phytophthora ramorum fungus, a plant disease commonly known as sudden oak death.
She is based at the Southwest Oregon Forest Insect and Disease Service Center which is located in the U.S. Forest Service's J. Herbert Stone Nursery in Central Point.
Given the potential damage it could cause in Oregon, early detection is essential, Goheen said, noting there are about 100 host species. It kills tanoak and black oak, and attacks madrone, myrtle, rhododendron, evergreen huckleberry, camellia and other shrubs.
In addition to being a valuable tree for wildlife, tanoak's commercial value includes providing a source for making pallets and wood chips, she said.
The hardwood tree can be found inland as far as the eastern side of Josephine County. There are about 1 million acres of tanoak in Oregon, of which roughly two-thirds are on federal land, she said.
"The pathogen could spread all the way up the coast in rhododendron and evergreen huckleberry," Goheen said. "They are contiguous hosts all the way up into British Columbia."
In an effort to keep a close eye on the pathogen, scientists have established 65 early detection devices in streams in the quarantined area. Every two weeks, the leaves are replaced, and the old ones are sent to Oregon State University where they are checked for evidence of the disease.
"Scientifically, it's fascinating," Goheen said. "It' is not a stream-borne pathogen. It's airborne. But we can pick it up when the spores are washed out of the canopy into the creeks and collected on the leaves."
Once it is determined the leaves contain the spores, investigators head upstream to find the infected plants.
"That can be really challenging," Goheen said, referring to the rugged coastal mountains covered with thick vegetation.
Swathed in rain gear, she hiked up a steep trail that followed the stream, walking for a half hour through a torrential downpour. The trek took her through Oregon's lush rain forest of towering coastal redwoods, cedar and fir. Sword fern covers the steep ground.
She finally reached a 10-acre site where all the tanoak, rhododendron and evergreen huckleberry had been cut, stacked and burned, leaving only the conifer trees.
Sudden oak death had been traced to the site, thanks to the downstream early detection system. But it took six months of slogging through the thick rain forest to track down the infected trees, she said.
Before leaving the area, the visitors' boots are sprayed with a bleach solution to kill the spores.
"Everyone wants to stop this pathogen from spreading," Goheen said, adding later, "But it's a very complex disease. It'll be a challenge."
Reach reporter Paul Fattig at 776-4496 or e-mail him at email@example.com.