Emerald Ash Borer treatment time

Asked June 26, 2015, 9:20 AM EDT

We've heard more than rumors of the confirmed Boulder infestation spreading. It's been said that the infested trees were taken to Broomfield for holding. Some are recommending preventive measures be taken next year, even though there has been no confirmed spread. Or has there?

Anyway, we'd like to start next year by applying Merit in a root drench. Application in the U.S. is supposed to be between mid-March through late April. What do you recommend for Englewood, Colorado?

Arapahoe County Colorado

3 Responses

EAB has been confirmed within 14 separate square-mile grid sections within the City of Boulder. To date, EAB has not been detected outside of the Boulder city limits.

If / when EAB is detected within 10 miles of your location, preventive measures can be taken in spring. These include insecticides applied as a soil drench or injection, trunk sprays or trunk injections.
See that your location is in Zone 3 (EAB Planning) at the EAB Management map https://mapsengine.google.com/06606903391052419324-13464369061086462890-4/mapview/?authuser=0

Only healthy ash trees with good structure are worth the expense of costly treatments and the tradeoff of possible environmental side effects.
Meanwhile, three years of early season freeze injury and the November 2014 'Polar Vortex' freeze have taken their toll on ash trees. Many stressed ash trees have been damaged by Lilac-Ash borer. See http://www.ext.colostate.edu/pubs/insect/05614.html
and www.eabcolorado.com.

Thank you. The Natural Way Landscaping is recommending preventive treatment in Englewood, Arapahoe CO next year. When is the best time of the year to do preventive, soil injection treatment? April? Thank you, David

At or about when buds break to push leaves. This will normally be around late April.