Emerald ash borer: What Front Range, northeast Colorado communities need to know

With the highly destructive emerald ash borer now confirmed in Colorado, many Front Range homeowners have questions about their ash trees and the risks presented by the invasive tree insect. Late last year EAB, already responsible for the death or decline of tens of millions of ash trees in more than 20 states, was detected in the city of Boulder. It poses a serious threat to northeast Colorado’s urban forests, where ash species comprise an estimated 15-20 percent of all trees.

To help homeowners and communities make decisions about dealing with the pest, this week the Colorado State Forest Service is releasing a new Quick Guide about EAB in Colorado. Primary recommendations for the Front Range and northeast Colorado include:

• Determine now if you have any ash trees. The first step to dealing with EAB is identifying susceptible host trees on the landscape, which include virtually any species and varieties of ash (genus Fraxinus). Ash trees have diamond-shaped bark ridges, compound leaves with 5 to 11 leaflets, and their leaflets, buds and branches grow directly opposite from one another.

• Recognize signs of EAB infestation. Homeowners with ash trees should be on the lookout for signs of EAB infestation, which include: thinning of upper branches and twigs, loss of leaves, D-shaped 1/8-inch holes on the bark, vertical bark splitting or increased woodpecker activity. Any suspect trees should be reported to the Colorado Department of Agriculture at 888-248-5535 or email CAPS.program@state.co.us.

• Be aware of EAB imposters. Other insects like lilac/ash borer, ash bark beetle and flat-headed appletree borer may look like EAB or cause similar tree symptoms. For more information, see the new EAB guide at www.csfs.colostate.edu.

• Know when treatments are (and aren’t) a good option. Homeowners have the option to apply chemical treatments this spring to help protect high-value trees, but treatments are not recommended more than 5 miles from a positive detection. Currently, the only confirmed in-state detection has been in the city of Boulder.

• Realize that treatments are necessary to save impacted trees. All ash trees, regardless of species, size or age, can be infested by EAB. Infested trees will not survive without treatments, but treatments can be effective even in infested trees, if infestation is detected early enough.

• Avoid planting ash trees in Colorado. Ash trees have been widely planted here, but due to the risk of EAB, future plantings are not recommended. However, this spring is a good time to consider planting diverse tree species where ash trees growing now may be lost in the future.

• Prevent further spread of EAB. Don’t ever transport ash firewood, or any other untreated ash wood products, to other locations. Boulder County and small adjacent areas are now under a federal EAB quarantine, allowing for stiff fines for those who move untreated wood from the area.

For more information about EAB infestation, treatment options and ash tree identification, view the guide online at www.csfs.colostate.edu or pick up a free copy at the nearest CSFS district. For current information about EAB in Colorado, including the current quarantine, go to www.eabcolorado.com.