Emerald Ash Borer (EAB) Background

Emerald Ash Borer (EAB) was found in the City of Boulder on September 23, 2013, by City of Boulder Forestry Staff. EAB is a non-native, wood-boring beetle that attacks native ash (Fraxinus) tree species. The Emerald Ash Borer is a state- and federally-regulated invasive pest that is responsible for the death of tens of millions of ash trees in 25 states and Canada. Unfortunately, this is the first time that EAB has been detected in the state of Colorado. EAB is a highly destructive, non-native insect that infests and kills all North American true ash species including green, white, black and blue ash, and their cultivars (including autumn purple ash, a popular white ash varietal in Colorado). The larval stage of EAB feeds under the bark of trees, cutting off the flow of water and nutrients. Infested trees gradually die over a period of approximately two to four years

This invasive insect has cost municipalities, property owners, nursery operators and forest products industries billions of dollars, and it is responsible for the death or decline of millions of ash trees in 25 states and Canada. An estimated 15 percent or more of Colorado’s urban and community trees are ash, and many of these trees are located on private property. EAB infestation is almost always fatal to infested ash trees, unless treated, and infested trees will be dead within approximately four years. EAB is the most destructive forest pest in recorded history.

At the Colorado Chautauqua, ash trees make up over 30% of the National Historic Landmark’s tree canopy.

To sustain and preserve Chautauqua’s tree canopy, Colorado Chautauqua Association (CCA) is taking action in three ways:

Tree Treatment- CCA, along with the City of Boulder, has opted to chemically treat a selection of beautiful and significant trees in the park, in an effort to save them. The pesticide Tree-äge, which is applied through injections through bore holes around the base of the trunk, has been shown to be extremely effective. Treated trees tend to survive as long as they are treated every 2–3 years, and the treatment may protect nearby trees.

Tree canopy underplanting – A diverse tree canopy is the most sustainable canopy for the long term. CCA will begin planting new tree species in the shadow of ash. If these smaller trees are planted prior to the infestation of an area, they will have a head start on becoming large, healthy and well-established.

Tree removal ­– CCA will remove trees as they become visibly infected and/or are deemed a hazard.