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February 19, 2019

EAB Newsletter | Winter 2019

Quarantine Reminder • Plans for Addressing EAB • When to Treat and Replant

Boulder County removes ash during the cold season from September to April to avoid the times when the Emerald ash borer is in flight and therefore avoid spreading the bug more. Trees marked with blue “X”s will be removed during this time.

Ash trees in the right-of-way will be removed unless they are being treated by an adjacent homeowner or homeowner’s association. Permit holders are responsible for scheduling and paying for treatment in accordance to the terms and conditions.

For more information, tree removal maps, and to apply for a permit visit

Treated ash trees versus untreated ash trees with an infection

Most EAB chemical treatments should be applied in the spring when the trees are leafing out for best results.

Contact a licensed applicator to get on their list for spring treatment.

Have questions about hiring a tree contractor? Considerations for Hiring a Contractor to Help Manage Your Ash Tree

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EAB beetle with wings open

In the state of Colorado, Boulder County is still the only county with EAB detected.

There is a quarantine around Boulder County that prevents ash wood from leaving the county without being properly treated. Learn more about the state-issued quarantine.

Before or after an ash tree removal

Optimum planting periods in Colorado are from March 15 to June 15 and from Sept. 1 to Oct. 15.

New trees can even be planted near living trees to give them a head start before the older ash are removed, called “shadow planting.”

The Front Range Tree Recommendation List is a good source for trees that grow well in Boulder County. Trees rated ‘A’ or ‘B’ are best suited for the Front Range, while trees with ‘C’ rating may grow well when planted in an ideal location. Refrain from selecting trees with ‘D’ ratings as this group is highly susceptible to local pests and/or diseases.

Tree planting