What Is Killing Our Utah Fir Trees?

Oct 5, 2018

Today’s topic has to do with something that is going on in our high elevation mountains. This is a concern because some of our native trees, in particular, the sub alpine fir and the white fir, so these are the true firs, are having some problems with an insect infestation. 

This is caused by the balsam woolly adelgid. It was first observed killing subalpine firs in northern Utah forests in 2017. However, it has probably been here for quite a bit longer. It’s now confirmed in at least eight counties.

This tiny aphid-like insect was first detected in the U.S. in 1908 so it’s been in the U.S. for quite a long time. It’s native to Europe. Through multiple introductions and spread it now infests true firs over most of the country.

The balsam woolly adelgid is a tiny sucking insect that feeds on the branches and trunks of true firs. It causes a decline in crown health and causes reduced cone and seed production. Through its feeding, it will cause abnormal swelling called gouting on the branches.

The U.S. Forest Service and state partners are now undertaking and intense monitoring effort to identify balsam woolly adelgid infested stands of sub alpine fir in high elevations of northern Utah. The decline of sub alpine fir is of great concern. Loss of this tree can inflict ecological damage through increased erosion, a decline in watershed health, loss of wildlife and their habitat and reduction in recreational values. These firs grow commonly along the ski slopes of Utah.