Forest Hill Drive and Guerilla Hollow are closed on Sunday, May 25 due to high winds.

What Happened to That HUGE Ash Tree?

By Renee Frith

As many are aware, emerald ash borer (EAB), is responsible for the sharp decline of Fraxinus sp. (Ash). The adult beetle is a shiny metallic green that is no more than ½ inch in length, but the larval stage is what does the damage. These grub-like larvae tunnel under the bark layer, usually through an existing crack, and begin feasting until it’s time for them to become an adult, and the whole cycle starts over. Ash trees are their preferred host, so the shiny adults flock from one ash tree to the next having the time of their lives, leaving a paralyzed and depleted stand of once lush ash trees in their wake.

EAB photo credit: burnsvillemn.gov

Recently we had the top removed from one of our ash giants in the Arboretum. As you drive around Arboretum Loop you round the turn at Let There Be Light, pass the entrance to Guerilla Hollow Road (home of L+A+N+D), and look to your left just past the parking lot. What was once a goliath ash tree, has now been tamed into an imposing silhouette.

LimbWalker Tree Service removing Ash Tree canopy

Bernheim made the decision many years ago to not use insecticides and fungicides, as many of these chemicals are non-target control, meaning they will kill any insect or fungi. Since there are many more beneficial insects and fungi than not, one can end up doing more harm than good by using these toxic chemicals. Bernheim took a very definitive stance with controlling EAB in that we do not want to apply the suggested neonicotinoids, because the application is not a one-time cure. This chemical would need to be applied annually for the tree’s life, and Bernheim decided not to have a chemically dependent species. We have chosen to allow the ash to decline. We monitor that decline and decide on when to remove the tree. In continuing to monitor decline, we are looking for signs of resistance. There very well could be a resistant ash specimen out there!

In the case of this HUGE ash tree, the time for partial removal was this year. We have been monitoring the decline over the past 5 years and noticed this year that some of the canopy branches were becoming extremely brittle. We are grateful to Limbwalker Tree Service for donating their time and talent and removing the canopy of this once exquisite specimen.

What happens with the remaining trunk, one may ask? Currently, that is up for discussion and to be determined. For more information about EAB please visit the University of Kentucky Emerald Ash Borer. 

(EAB): Resources and Updates: https://entomology.ca.uky.edu/entfact/kentucky-emerald-ash-borer-eab-resources-updates

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