Tamarack in trouble
By JAYSON JACOBY
Of the Baker City Herald
The flamboyant displays of foliage that brighten Baker County's forests every fall might seem a tad drab this year.
The stars of the show are sick.
They are western larch trees although if you want to fit in at a local social gathering you'd do well to call them "tamaracks" instead.
Tamaracks are conifers, which means they bear their seeds in prickly cones, just like a ponderosa pine or a Douglas-fir.
But there's a difference:
Unlike pines and firs, which keep their needles year-round (hence the term "evergreen"), tamaracks, which seem to think they're some sort of maple, shed their pale-green needles every autumn.
But before those needles fall silently to the forest floor, they turn a unique shade of shiny yellow-orange.
A lone tamarack, standing 80 feet tall and clad in its fall finery, gleams like a pillar of fire amidst the dour green backdrop of pines and firs and spruces.
On the slopes of the Elkhorns that loom over Baker Valley, tamaracks grow in groves across a relatively narrow elevation range, so that in October the mountains' dark flanks appear to be accessorized with a bright orange belt.
But maybe not this October.
A needle-chomping insect, the larch casebearer, is attacking tamaracks across Baker County, said Jim Gilsdorf, a silviculturist for the Wallowa-Whitman National Forest.
Although casebearer larvae gnaw needles, leaving them a rusty brown color, the insects probably won't kill any trees, Gilsdorf said.
"I would be surprised if we saw much, if any, mortality," he said.
Larch casebearers can kill tamaracks if the insects breed in large numbers for four or five years in a row, but Northeastern Oregon's climate seems not to be conducive to long-term infestations, Gilsdorf said.
The insects always are present, he said, although usually in populations so small that only a few scattered tamaracks turn brown in a given year.
"We had some last year, but this year they seem to be more widespread," Gilsdorf said. "I'm seeing more and more as I'm going around. And we've had a few calls from people wondering if the trees are dead."
Gilsdorf emphasizes the point because he wants to remind firewood cutters to be certain a tamarack is dead before they saw it into stovelengths.
If the needles are brown but there's a bumper crop of them, the tree is alive, and thus off-limits to woodcutters.
Continuing casebearer attacks can leave tamaracks vulnerable to other pests, including the western larch borer, bark beetles and a root disease, but Gilsdorf said tamaracks are much more adept at repelling such invasions than are most other conifers.
"The good thing about larch is it doesn't have a lot of other (insect) species that tend to attack it," Gilsdorf said.
Besides, most tamaracks lose their needles by Halloween anyway, insects or not, so shedding the needles a few months early leaves no permanent damage.
Pines and firs, on the other hand, sometimes fight off one insect or disease only to succumb to another.
And the pests that prey on evergreen conifers spruce budworms and Tussock moths on firs, and a variety of beetles on pines are much more likely to kill trees than larch casebearers are, Gilsdorf said.
"The (larch casebearer infestation) is much more benign," he said.
Unlike tamaracks, firs can't replace amputated needles.
And no one builds prosthetics for pines.
But even if the current casebearer infestation is less than lethal, the diminutive larvae a mature larva stretches only a fifth of an inch certainly could put a damper on many a family's autumn tradition of driving into the mountains to gaze at the inimitable spectacle of iridescent tamarack needles framed against blue sky.
There is, however, reason to be optimistic.
Tamaracks sometimes produce a second crop of needles in late summer, Gilsdorf said.
Casebearers might well chew on the new needles, too, he said.
But it's possible that the fresh needles will survive long enough to undergo the colorful autumn transition so beloved by sightsteers and photographers.