3 Steps to Save Ash Trees From the Emerald Ash Borer

The Emerald Ash Borer (EAB) is on the move!

Denver is a city teeming with Ash trees. One in every six urban trees in the Denver area is an Ash, so the trees help fill out the canopy in parks, greenbelts, and landscaping. The destructive Emerald Ash Borer (EAB) broke out its quarantine in Boulder in 2019 by spreading to Westminster and Broomfield. The City of Arvada confirmed the jewel beetle within its city limits on June 18, 2020. The insect is about six miles from the Denver area. The insect is highly destructive to White and Green Ash trees because they possess no immunity to the insect and its larvae. Without treatment, all Ash will die.

The EAB could be in Denver now, but the jewel borer is hard to detect because most of the harm to Ash trees is underneath the bark. So prevention is the best approach to managing yard Ash trees. It is important to note that all city foresters along the Front Range, including Denver’s, expect homeowners to address the Ash in their yards.

Need to know your EAB treatment options? Ross Tree is at your service. Click here to fill out a request service form or call 303-871-9121.

adult emerald ash borer
Below are three ways you can help defeat the deadly EAB.

1. Identify Ash Trees on Your Property

If you live in or around the Denver region, inventory your trees to determine which are Ash. A tree service professional can help you identify all of your trees if you aren’t sure. After identifying and tagging your trees, decide which trees are worth saving should the EAB infest your Ash trees. Arborists recommend removal for any trees growing in marginal areas. Smaller trees affected by EAB need removal by professional tree companies. Mature, stately Ash trees may be salvageable but need treatment now.

2. Recognize the Signs of EAB Infestation

The jewel ½-inch long EAB insect catches the eye. The wings and head are metallic green. When the wings separate, you see the purplish-bronze abdomen. However, by the time you spot an EAB infestation, the tree was infected years old. That’s because the EAB larvae can remain under the bark of trees for several years before the adults emerge. Other signs of EAB infestation include:

  • Thinning canopy
  • Sparse foliage on random limbs
  • Green shoots growing from the trunk base
  • D-shaped adult exit holes
  • Serpentine-shaped tunnels under the bark
  • If bark splits along the trunk of an Ash tree, this is a sign of EAB damage. As the larvae tunnel through the vascular layers of the tree, the wood becomes less flexible. The bark cracks with
  • The presence of the Northern Flicker woodpecker. This brown bird pecks away at the Ash tree’s bark to reach the juicy larvae inside.

When To Contact Your Tree Service Company?

Now! All city foresters along the Front Range, including Denver’s, expect homeowners to manage the Ash in their yards. Your tree service can apply preventative treatments to your trees that are not infected. If trees have only a few galleries of EAB, a systemic insecticide will most likely save the tree. Ross Tree offers expert tree injections to help prevent and treat EAB infestations in the Greater Denver, Colorado region.

However, treatment can’t undo any damage done to the tree. Extensive larval galleries under the bark severely compromise the tree’s phloem and xylem nutrient-transporting layers, so a systemic insecticide won’t be able to travel through the tree’s vascular system. If that is the case, a tree service professional uses foliage sprays to target the adult beetles. Mature females consume Ash foliage for at least two weeks before they lay eggs, so non-systemic foliage sprays cut down on new infestations.

EAB Rules of Thumb

  • If more than 50 percent of an Ash tree’s canopy has died back due to EAB, it is best removed.
  • Trees with less than 50 percent dieback might be treatable.
  • After treatment, trees may look worse but usually come back within a few years as the canopy foliage grows.

Homeowners looking for more information about the EAB treatment, click here to view Ross Tree’s EAB Handbook.