Swiss Needle Cast
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truffler1635 at my-deja.com
Sat Sep 9 11:28:59 EST 2000
>From The Oregonian, Sept. 8, 2000, p D4
RESEARCHERS SAY FUNGUS AFFLICTING DOUGLAS FIRS MAY HAVE PEAKED
The epidemic hit along the northwest Oregon coast, causing many valuable
trees to lose their needles
By MATT SABO
CORRESPONDENT, THE OREGONIAN
Aerial surveys the Oregon Department of Forestry conducted this
summer indicate that he spread of Swiss needle cast, a fungus that stunts
Douglas fir growth in coastal timberlands, may have peaked.
The fungus has afflicted trees on 283,000 acres of timberland in
Oregon, down slightly from 1999's total of 295,000 acres, said Alan
Kanaskie, a forest pathologist with the Forestry Department.
The agency says as much as 75 percent of state forest land in
northwest Oregon is affected by Swiss needle cast. About 75,000 acres of
trees with two years or less of foliage retention show severe damage from
Scientists are uncertain whether the lower number in this year's
survey is a result of mapping errors or whether the spread of the fungus
is leveling off, Kanaskie said. "We'll see what next year's surveys
Forest scientists said a cycle of cool, wet weather beginning in the
1990s triggered the rapid spread of the fungus. Swiss needle cast causes
Douglas fir needles to turn yellow and fall off prematurely, slowing or
halting tree growth. The fungus spreads by mobile spores.
Swiss needle cast thrives in wet weather, particularly in fog-laced
slopes, and is concentrated within 20 miles of the coast from Lincoln
County north into Washington state. Tillamook County forests have been
hardest hit, Kanaskie said.
"The fungus was building, we think, for many decades," said Greg
Filip, an associate professor at Oregon State University's College of
Forestry. "It just took something to trigger it. We don't see an end,
that's for sure. I think the end may come when we get some dry-weather
climates.+i.+i.but that may not be for another 10 years."
Douglas fir has been Oregon's "bread and butter," Filip said. The
tree grows quickly compared with other softwood species and is milled
into studs and boards for housing.
Though the exact cause of the epidemic is unknown, OSU experts said
intensive, even-aged cultivation of Douglas fir could be part of the
problem, along with the recent climate trends. In the old-growth forests
of the Northwest, which have trees of many species, sizes and ages, the
fungus has caused no big outbreaks in recorded history, they said.
Private timberland owners are cutting diseased stands of trees and
replanting them with a mix of species rather than growing plantation-
style Douglas fir stands, Filip said.
Alternatives include hemlock, cedar, spruce and alder, but
landowners' demand for seedlings exceeds supply, and nurseries are unable
to meet orders, he said. "You may see some bar areas until they get some
of the other species in there."
Barte Starker, executive vice president of Corvallis-based Starker
Forests Inc., said he and other timber owners remain concerned about the
spread of the fungus. "It caught us by surprise in that we've known about
Swiss needle cast for years."
It first turned up in 1925, at a time when the United States was
shipping young Douglas fir trees to Europe for planting. People in
Switzerland discovered the fungus and warned foresters here, leading to
the misnomer "Swiss needle cast."
The fungus showed up on Christmas tree farms in the Willamette
Valley during the 1970s. That was potentially devastating because
unhealthy or discolored yule trees are worthless. Christmas tree farmers
fought the disease successfully with fungicides, but that would be
impractical for timberland owners, who would have to spray the chemicals
after every spring rain.
Swiss needle cast, native to the Northwest, most often turns into a
full-blown disease in trees 10 to 30 years old. Some trees lose their
needles after two years, others after a century or more.
Symptoms occur when microscopic spores, clinging beneath tree
needles, germinate and plug breathing holes known as stomata. The fungal
growth, which sprouts into tiny black blobs, seems to favor the warm, wet
weather common to Oregon's coast.
Researchers are studying the fungus, searching for possible causes
and potential solutions to the epidemic, and are trying to develop
genetically resistant Douglas fir varieties.
The needle cast outbreak as reinforced the concept of planting
diverse forests that are more resistant to cycles of disease or pest
infestation, Starker said. Despite its toll, however, he sees a benefit
to the epidemic. "Whenever we have a mini-crisis, we learn tremendous
amounts and push ourselves to learn deeper about things."
Comment by poster: While the article says most of the outbreak is located
along the coast, there is a considerable amount present in the Cascade
Range as well. The Cascade foothills of Clackamas county are well-
involved, and have been for some time. Once again, it is time to assess
the "traditional" re-planting regimen of only Douglas fir after logging.
Plantation rotations are ripe for SNC. Interplantings of other tree
species, including White pine, Whitepark pine, Western hemlock, Red alder
and oak would strongly decrease SNC by spacing out potential host trees
farther apart, and interrupting dispersal of spores. Several studies have
also shown that Red alder mixed with Douglas fir tend to grow both trees
more rapidly than a single-species planting of either species.
Daniel B. Wheeler
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