emerald ash borer

Asked May 31, 2018, 10:17 AM EDT

I am a home owner in Fort Collins and am receiving mixed messages about the need to treat my ash trees for emerald ash borer. According to the city forester, EAB is currently in Boulder. He is recommending not treating until it reaches Longmont. In addition, my neighborhood HOA is NOT treating this year. However, my commercial tree company is recommending treatment now. Please advise. My trees were treated last year using an imidacloprid soil application. I've heard that this treatment should be good for 2 years so I'm also confused why it needs to be repeated again this year.

Thank you.

Larimer County Colorado trees and shrubs

1 Response


With Extension (and city forestry offices and the Department of Ag), our goal is to provide outreach education and the information to let you make a decision that's best for your trees. We do not sell any products or services.

Our position is that treatment in Fort Collins is unnecessary at this time and aligns with what the City of Fort Collins Forestry staff told you. This insect has still only been detected in Boulder County (though it WAS been confirmed in Longmont).

The commercial tree care companies may have other reasons to push for treatment, one being financial. The product they used last year, imidacloprid, only has efficacy for one season, which is why they are recommending treatment again.

Trunk injections (using emamectin benzoate or azadiractin) last for two seasons, possibly three.

If treating your tree now seems like the best choice for YOU, then we would not discourage you. However, this insects has not been found within Larimer County, so treatment at this time could be considered unnecessary.