Archive for April 6th, 2009

Tough time for trees

by Brent Carmack, Assistant Director, Fort Collins Museum

It’s been a tough time for trees at the Fort Collins Museum in recent months. Right at the end of 2008 a huge 60 foot spruce blew down on the west side of the Museum (see our Flickr site and check out the “Windstorm” photo set). Last week City Foresters took down a Ponderosa pine tree located at the southwest corner of the Museum that had been attacked by mountain pine beetles.

Pine beetle larva

Pine beetle larva

For a long time this tree had appeared weak, but as the Forestry folks were taking the tree down they showed us just how bad things had gotten. Peeling back some of the bark revealed mountain pine beetles in adult and larval form. There were yellow spots all over the trunk of the tree. The branches coming off the tree were dry and brittle and weighed next to nothing as there was no sap left in the tree.

My family has camped for several years in a row at what I consider the finest campground in the state, Pearl Lake State Park, north of Steamboat Springs. In recent years we could see the devastation that the pine beetle was creating on the western slope of Colorado, to the point where the campground is closed this year while they remove many of the dead trees. I had thought that the pine beetle infestation was primarily a western slope problem, but David Sexton of the City’s Forestry Department told me that pine beetles have made their way to Fort Collins and are beginning to attack weaker pines in the city.

Pitch tube

Pitch tube

David said that beetles have most likely been carried on the wind from the western slope and landed in Fort Collins. He explained that the yellow spots on our tree are called pitch tubes and indicate where the beetles bored into the trunk and the tree tried to push back — but to no avail, because it was already weak. When beetles attack stronger trees the pitch tube is usually white and sometimes you can see a beetle stuck in the pitch, an indication that the tree is healthier and potentially winning the battle with the beetles.

Blue stain caused by pine beetle infestation

Blue stain caused by pine beetle infestation

One interesting side effect of a beetle-killed tree is a blue staining of the wood which is caused by a fungus that the beetle introduces to the tree. The result is an eerily blue hue to the wood as compared to the normal yellow color of pine. The sheer volume of beetle-killed trees has resulted in a new market for beetle-killed pine in the construction business. The finished blue-tinted pine makes beautiful furniture, window sills and other finish pieces in homes.

To learn more about mountain pine beetle, how to spot signs of infestation and how to protect your trees, visit the website of the Colorado State University Extension Office.


April 2009
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