Emerald Ash Borer presents a significant threat to Ash Trees throughout Colorado
Emerald Ash Borer was discovered in Boulder, Colorado in September 2013. This puts every ash (not Mountain Ash) within 15 miles of Boulder at risk. The Emerald Ash Borer is an Asian pest with no natural enemies in North America, thus it is considered an invasive species. As a result of this invasion, it will attack and ultimately kill every untreated ash tree in an affected area. The pest can spread up to 10km in a single year, and the lack of natural predators means that their lethality is up to 100% of ash trees in a 10 year period. The small, iridescent green beetle was likely introduced through imported construction materials, and is thought to spread by the transportation of infected firewood. The potential economic impact of the Emerald Ash Borer is significant, as Ash trees are generally prized for their appearance, and removal of a single infected tree can cost hundreds or thousands of dollars. Cities and municipalities that have to deal with large numbers of infected trees can incur millions in costs, and budgets must be amended to deal with the infestation.
Like other invasive tree beetles, Emerald Ash Borer eggs are deposited in the bark of the ash tree. After approximately two weeks, beetle larvae hatch as a small grub or worm-like insect and bore into the phloem and outer layer of sapwood where they feed until cold winter weather arrives. The larvae then overwinter, morphing into the intermediate life-cycle stage of pupae. The following spring, adults chew their way to the tree surface to fly away and continue the life-cycle. The burrowing results in damage to the nutrient pathways utilized by the tree. This cyclic process can take years to kill a healthy mature tree, but if left untreated, that will likely be the outcome. A healthy, treated tree is the best way to prevent and stave off infestation – a good defense being the best offense.
Several common myths exist regarding the infestation of the Emerald Ash Borer. First and foremost is the myth that nothing can be done to stave of infestation. Insecticides such as TreeAzin by BioForest Technologies can be used on trees of at least 8-inch diameter, and Safari by Valent can be used on smaller trees. These systemic insecticides are applied by direct injection and remain effective for one to three years. In addition, infected trees can be removed at first sign of infection, potentially preventing the spread of the Emerald Ash Borer. A combination of both aforementioned strategies is recommended. A second common myth regarding the Borer is that the pest does not pose a threat to humans. While the insect itself does not harm humans, the product of its life-cycle, dead trees, present risks to both persons and property. Large dead trees and limbs can fall unexpectedly in strong winds common to the Colorado landscape. In addition, the loss of mature trees has been found to reduce air quality in a given area, as mature trees make a large contribution to air quality, moisture levels, and shading.
Like other invasive tree beetles, Emerald Ash Borer eggs are deposited in the bark of the ash tree. After approximately two weeks, beetle larvae hatch as a small grub or worm-like insect and bore into the phloem and outer layer of sapwood where they feed until cold winter weather arrives. The larvae then overwinter, morphing into the intermediate life-cycle stage of pupae. The following spring, adults chew their way to the tree surface to fly away and continue the life-cycle. The burrowing results in damage to the nutrient pathways utilized by the tree. This cyclic process can take years to kill a healthy mature tree, but if left untreated, that will likely be the outcome. A healthy, treated tree is the best way to prevent and stave off infestation – a good defense being the best offense.
Several common myths exist regarding the infestation of the Emerald Ash Borer. First and foremost is the myth that nothing can be done to stave of infestation. Insecticides such as TreeAzin by BioForest Technologies can be used on trees of at least 8-inch diameter, and Safari by Valent can be used on smaller trees. These systemic insecticides are applied by direct injection and remain effective for one to three years. In addition, infected trees can be removed at first sign of infection, potentially preventing the spread of the Emerald Ash Borer. A combination of both aforementioned strategies is recommended. A second common myth regarding the Borer is that the pest does not pose a threat to humans. While the insect itself does not harm humans, the product of its life-cycle, dead trees, present risks to both persons and property. Large dead trees and limbs can fall unexpectedly in strong winds common to the Colorado landscape. In addition, the loss of mature trees has been found to reduce air quality in a given area, as mature trees make a large contribution to air quality, moisture levels, and shading.
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