The city is contracting with Taddiken Tree Company to preventively treat ash trees from the impending Emerald Ash Borer (EAB) infestation. Taddiken will start the treatments in late July on about 400 city-owned ash trees located in parks, city facilities, street medians and rights-of-way. The 2019 treatments will be focused in central Westminster near City Park and the Promenade.

EAB is an invasive pest that has killed millions of ash trees throughout the eastern US and Canada. It was confirmed in Boulder in 2013, Gunbarrel in 2015, Longmont in 2016, Lafayette in 2017 and Superior in 2018. Movement of the pest from one area to another is usually through the human spread of ash wood, including firewood.

EAB has not been detected in Westminster yet. It is difficult to detect early infestations and the borers have usually been in the trees for one to three years before detection. It is anticipated that EAB will be detected in other parts of the Denver Metro area, including Westminster, in the next year or two.

Westminster has about 1,700 city-maintained ash trees and about 1,200 of those trees are healthy enough to qualify for preservation treatments. The goal is to treat one third of the trees on a 3-year rotation basis. The city’s forestry crew treated 205 trees in 2017. The trees will be treated with emamectin benzoate, one of the most effective and environmentally friendly EAB pesticides. The treatment is a trunk-injected pesticide that lasts up to three years and is applied by a licensed commercial pesticide applicator.

The Colorado Department of Agriculture has a quarantine on the movement of ash tree material and firewood outside of Boulder County. This quarantine is anticipated to be dropped at the end of this year due to lack of funding and the inability to enforce. Once the quarantine ends, ash tree logs and material will be transported to and through Westminster, increasing the risk of spreading EAB.

There are an estimated 69,000 privately-owned ash trees in Westminster; about 1 in 7 trees in Westminster is an ash tree. If they haven’t done so already, it is time for ash tree owners in Westminster to consider having their ash tree treated. It is less expensive to treat trees than to remove and replace.

For information, please contact: City Forester John Kasza at 303-658-2559 or jkasza@westminsterco.gov or Assistant City Forester Bryan McCoy at 303-658-2287 or bmccoy@westminsterco.gov.