Wednesday, December 9, 2009

Bark beetles threaten Baldy tree stands

Preventative measures proposed for stands on Warm Springs side

Express Staff Writer

Joe Miczulski, a winter sports specialist with the U.S Forest Service, above, points along Guyer Ridge on Bald Mountain to trees that were scorched by the Castle Rock Fire in 2007. The fire made trees within the ski area susceptible to infestation by the Douglas fir bark beetle, which will likely cause trees along the upper Warm Springs slopes to turn red and begin dying next summer. Infested trees can be identified by the presence of “frass,” right, a fine reddish-brown dust expelled by the beetles as they bore through the inner layer of bark. Photo by Willy Cook

There's hardly a more iconic moment in the Sun Valley area than taking in the view of Ketchum and the surrounding Pioneer and Boulder mountain ranges from the top of Bald Mountain, then carving down the Upper Warm Springs ski run while flanked by snow-dappled evergreen trees.

But due in part to the Castle Rock Fire, which swept through the eastern Smoky Mountains in summer 2007, those same trees might not be so green by next winter. The fire helped augment a dramatic rise in the population of the Douglas fir bark beetle, which is now infesting its namesake trees throughout thousands of scorched acres and threatening healthy trees as well. The phenomenon could take place all over Baldy if preventative actions are not taken.

"We don't know how many trees are infested, but people shouldn't be surprised to see trees change colors from yellow to red to brown over the course of next summer," said Joe Miczulski, recreation and winter sports specialist for the U.S. Forest Service's Ketchum Ranger District.

According to a report from Laura Lazarus, an entomologist with the agency's Forest Health Protection unit, the approximately 50,000-acre Castle Rock Fire left hundreds of thousands of trees in a weakened state, susceptible to infestation and damage from the beetles.

While healthy trees are able to produce enough sap to either drown the beetles or force them from beneath the bark, trees damaged by fire or drought don't have that capability. The weakened trees are unable to protect themselves as the beetles burrow into the inner bark and construct "galleries" to lay their eggs. When the eggs hatch, the larvae feed on a perpendicular plane so that if enough larvae are present, they will prevent the flow of water up from the roots and nutrients down from the needles. Eventually, this leads to the death of the tree.

"Insect surveys conducted in the summer of 2009 confirmed beetle populations have exploded and already infest some large, older green Doulas firs in timber stands between the ski runs and along Guyer Ridge on upper Warm Springs," Miczulski said in a news release on Monday. "Our goal now is to keep the next generation of beetles, which typically begin flying in late April, from spreading into green trees on lower Warm Springs and the River Run side of Baldy."

Looking at a Bald Mountain trail map, Miczulski said that the current situation shows the beetle-infested trees within the ski boundary limited to the area above Lilly Marlane and to the skier's left of Picabo's Street.

The infested trees can be identified by the presence of "frass," a reddish-brown dust resembling fine pencil shavings, which is expelled by the beetles and accumulates in the cracks of bark around a tree's base.

Once a tree is infested, there is no way to salvage it and it may die within a year.


Miczulski said the beetle population has grown so large due to the amount of stressed trees that the River Run side of the mountain could be in jeopardy if preventative action is not taken.

Last spring, the Forest Service attempted to stanch the beetles' spread by stapling small bags of the pheromone methylcyclohexenone (MCH) to trees along Guyer Ridge. About 1,250 pouches were stretched out in a strip about 250 yards wide from close to the top of the mountain to the Warm Springs parking lot.

The pheromone is naturally produced by the beetles to let other beetles know that there is no more room in a tree, thereby preventing overpopulation in a single tree. By replicating MCH and attaching it to trees that have yet to be infested, the Forest Service can trick beetles into staying away from certain areas and keep them hunting elsewhere for trees to infest.

This method was used with success in 2008 and 2009 in Central Park, a section of trees that stands between the Upper College and Upper River Run ski runs.

The deployment of the bags on Guyer Ridge did not prove to be impenetrable, though, and the beetles found their way over the defensive line and into trees bordering the upper sections of the International, Warm Springs, Limelight and Picabo's Street runs.

Miczulski said the failure was likely due to winds out of the Warm Springs area that scooped the beetles, which are not adept fliers themselves, over the line of bags and deposited them in previously unaffected areas.

The Forest Service is now proposing a new tactic—to spread tiny plastic flakes embedded with the MCH pheromone next spring, before the beetles emerge in June and look for new trees. Miczulski said the flakes, measuring 3 millimeters a side, would be applied by helicopter over a 4,000-acre area on Bald Mountain, about half of which would be within the ski area. By using a helicopter, the Forest Service would be able to cover an area in a single day that would take an entire summer on foot.

Miczulski said that although not biodegradable, the MCH flakes have never been connected with any adverse effects on humans, animals or the environment.

The Forest Service is asking for public comment on its proposal to spread the MCH flakes by helicopter, which would likely take place in early May and possibly a second time in early July.

Public comment should be received by Jan. 8 and sent to: Ketchum Ranger District, Attn: Bald Mountain Douglas-fir Beetle Project, Box 2356, Ketchum, ID 83340. Comments can also be faxed to 622-3923 or sent by e-mail to:

More information on the project can be found at the "Projects & Plans" tab on the Sawtooth National Forest Web site,

"We want people to understand that some of the trees on the mountain will start dying and there's nothing we can do but try to protect the rest of the majestic trees that Baldy is known for," Miczulski said.

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