Help Keep Invasive Pests Out Of Our Urban Forest

By Marilyn Loser

We’re big on global transportation today.  However, we’re becoming aware of the value of choosing items closer to home.  Local produce at farmer’s markets and restaurants is all the rage – I hope the rage continues!

The rage needs to extend into least two areas: firewood and tree purchases.

Firewood: buy it where you burn it.

Several years ago the drought in our area, perhaps in conjunction with warmer winters, devastated pinon forests in northern New Mexico and my back yard. Pine beetles are always present in pinon trees.  The hard-shelled beetle, the size of a fingertip, drills through pine bark and digs a hole in the wood where it lays its eggs. When the larvae hatch under the bark, they eat the sweet, rich cambium layer that provides nutrients to the tree. These sweethearts also inject a fungus to stop the tree from moving sap, which could drown the larvae.

During normal precipitation cycles most trees are healthy enough to withstand beetle damage. Some foresters believe the milder winters we’ve been experiencing have allowed the beetles to flourish and expand their range as they don’t die off in the winter.

During drought, the beetles can weaken the trees severely enough that they die.  As I drive south on Highway 285 into New Mexico through Tres Piedras and then either turn east to Taos or continue further south to Ojo Caliente, I’m amazed and saddened by the pinon forest depletion.  Now many homes are visible that were once hidden by the trees and entire hill sides are covered by dead trees.

A conservationist at heart and lover of pinon fires, I thought it would be a great idea to bring some of the dead trees home for firewood.  Then I wondered if the deadwood still had virulent pine beetles that I’d be transporting into my area. Turns out it’s very likely.

The Colorado Department of Agriculture asks outdoor enthusiasts to leave their firewood at home. “Moving firewood across the state can contribute to tree mortality,” said John Kaltenbach, CDA’s cooperative agricultural pest survey coordinator. “Insects and diseases can be transported with the wood and can hurt or even kill Colorado’s forests.” The CDA urges campers to buy their firewood at their destination, thus preventing the spread of any insects or diseases that can be found in or on the wood.

The mountain pine beetle has impacted almost 3 million acres of forests in Colorado. But it is not the only pest doing damage to United States’ forests. According to the CDA, the emerald ash borer is a beetle that has killed over 50 million ash trees in the Midwest. At this time, it has not been discovered in Colorado but the CDA is working to prevent the spread of this beetle to Colorado. Traps are set annually across the state as a tool for early detection.

Thousand Cankers, a disease carried by the walnut twig beetle, has caused the death of black walnut trees in Boulder and the Denver Metro area. While I don’t know of any black walnut trees in the Alamosa area, their story provides a cautionary tale (some sources say they are rated as low as zone 4 – I consider my yard zone 3, but I’m colder than downtown Alamosa). The primary method by which the beetle reaches new locations is the movement of infested wood including logs, firewood, lumber and even wood chips according to the CDA.

Buying new trees: Firewood is not the only way pests are transported from area to area. If you were to buy an infested ash tree in the Midwest and plant it in the San Luis Valley, you could be responsible for an epidemic.

You might unknowingly buy a tree right here in Colorado that is infested with an exotic pest.  I was startled to here foresters at the February Urban Forestry Conference in Springfield relate reports of Asian pests in trees in Pueblo and Colorado Springs.  Apparently, the trees were imported from Asia. You can avoid this situation by purchasing your trees from local nurseries who buy trees grown as close to our area as possible.

Cole Tree Planting: At last word, the trees for Cole Park from the Colorado Tree Coalition and the Alamosa Department of Parks and Recreation haven’t arrived yet.  I appreciate those of you who have offered to help plant.  I’ll be in touch as soon as I know planting dates.  We’ll be planting them over a period of a couple of weeks. You can contact me at

"Knowing trees, I understand the meaning of patience. Knowing grass, I can appreciate persistence." Hal Borland