Emerald Ash Borer – still here and on the move

Tue. Oct. 13, 2020

Click below to listen to my 2 min. Garden Bite radio show: Emerald Ash Borer – still here and on the move

The Emerald Ash Borer remains on the move and confirmed cases have now been established in Carver and Sibley counties in Minnesota, making them the 24th and 25th counties with confirmed EAB in the State. MDA staff were able to find live EAB larvae in infested trees on both sides of the county border and collected samples for federal identification. That means they are now under quarantine. I just talked about EAB in May… and said “it ain’t leavin'”… 

EAB – photo by Jeffrey Hahn UofMN

A great video by Jeffrey Hahn…

EAB has been found in certain parts of all the states from the East Coast west to Colorado. Wisconsin counts two more counties this year as well. However EAB seems to be mainly in the southeast corner of the State. However, where there are Ash trees, there will be EAB.

True ash species are highly vulnerable to EAB regardless of ash or total tree density, ash or total stand basal area, tree size and tree health. Researchers in Michigan and Ohio observed that ash survival decreased 30-50% over three years in infested stands in southeastern Michigan. Models developed from field observations predict that a healthy forest will lose 98% of its ash trees in six years.

EAB starts infesting trees at the top of the canopy and then work their way down, so by the time you see those holes, your tree’s been infected for a while.  Another definitive symptom is S-shaped squiggles, (my unofficial term) under the bark.  Obviously you can’t see these unless you take the bark off.

EAB larvae by Jeff Hahn
Canopy die back due to EAB photo by Iowa Tree Pests

The only places where the trees have a better chance is where temperatures drop to 30 below zero. While the insect spreads slowly on its own, EAB impacts are greatly accelerated when people unintentionally move it in firewood and nursery stock. That’s why the quarantines are put in place.

There are treatments for homeowners to use should they want to save their Ash trees. They’re not cheap, but if you have a beautiful tree or two it may well be worth it. And it should be done by a professional.

Here is more on EAB treatment and replacement trees.

EAB treatment