Emerald ash borer
I live in south Ft Collins, southwest of Trilby and Shields. Should I be treating ash trees for emerald ash borer in 2019?
Larimer County Colorado
As of today, emerald ash borer has not been found outside of Boulder County. The closest find to Larimer County is Lyons (also in Boulder County).
The City Forester in Fort Collins is not recommending treatment for Fort Collins at this time, nor does the City plan to treat any trees in 2019.
However, it's a good time to assess your tree and determine if treatment is the best option. Depending on the tree's health, size, and vigor, small trees may not be worth treating and replacement is a better option. Many towns/municipalities are using a 10-12" in diameter at chest height measurement to keep or remove trees.
Once treatment begins, it is a lifelong commitment (or as long as you own the property). Trees will need to be treated for the infinite future.