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Emerald Ash Borer is in Westminster


Emerald Ash Borer (EAB) is the most destructive and costly invasive tree pest in North American history and is responsible for destroying hundreds of millions of ash trees. EAB is rapidly spreading throughout the city of Westminster, all ash trees must receive preventative treatments every 2-3 years or they will be killed by the insect. In September 2019, EAB was confirmed in Westminster.

For City-owned trees on City property, the Forestry team has been assessing ash trees for treatment since 2013. Unfortunately, ash trees that do not meet the treatment criteria must be removed, as they will eventually be killed. Removing untreated trees early temporarily slows the spread of EAB, reduces risk to tree workers, and can speed up replanting efforts by prioritizing re-planting locations.

Learn more about the EAB

Now is the time to act to save your valuable ash tree! 

Do I have an ash tree?

Emerald Ash Borer damage

You probably do, 1 out of every 7 trees in Westminster is an ash.

Ash Tree Identification

Green ash, white ash and Autumn Purple ash (a type of white ash) were very desirable for landscape planting because they grow well under difficult conditions and have been widely planted. There are an estimated 69,000 ash trees in the city. To help with ash tree identification, the Colorado State Forest Service developed an ash tree ID app that can be downloaded by searching in app stores for "ash tree ID" or here: Ash Tree App.

Right-of-Way (ROW) Emerald Ash Borer Treatment Program

In Spring 2023, the City completed a Right-of-Way (ROW) tree inventory project to identify ash trees in the ROW. This study found 3,174 ash trees worth preserving. The City will provide preventative treatments on a one-time basis to preserve these trees from emerald ash borer.

ROW EAB Treatment FAQs

View map of ROW trees that will be treated

What can I do to save my ash?

1.      Call a tree care company to evaluate your trees and apply preventative EAB treatments. Healthy ash trees in a good location with a trunk diameter greater than eight inches can and should be saved! Treatment options can be found here.

2.      Act now! Get your ash tree on a recommended treatment cycle ASAP before it’s too late. The longer you wait, the more costly removals can become as trees rapidly decline.

3.      When selecting a company to treat or remove your ash trees, please check for proof of insurance and appropriate certifications.

How to Hire a Tree Care Company

Read the Westy Word article on EAB and IPS Beatle.