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  • Writer's pictureKassi K.

Protect Your Tree from Emerald Ash Bore

Updated: Sep 12, 2022

What is Emerald Ash Bore (EAB)?

Emerald ash bore is an insect that has the capability to severely harm the majority of ash trees here in Fort Collins. The urban tree canopy in this area is comprised of approximately 1/3 of Ash trees. This insect is highly aggressive and will kill any tree that is four inches in diameter and larger.

How do you know you have an ash tree?

Ash trees can be distinguished by their distinct diamond bark pattern. Here in Fort Collins, we have two varieties of Ash tree, the Green Ash, which displays bright yellow leaves in the fall, and the White Ash, also known as the Autumn Purple Ash, which displays vibrant purple leaves in fall. Otherwise, the leaves of these trees are a rather plain, normal-looking leaf, which grows from big, woolly buds in the spring.

Symptoms of EAB

Damage done by the Emerald Ash Bore can usually be seen first at the top of the tree. In late spring/early summer, the adult insects feed at the top of the tree, causing the defoliation of branches at the top of the tree. This is often the first sign that your tree is in danger. Once the adults are finished feeding, they bore into the tree and lay their eggs, which begins to disrupt the tree and its ability to move water and nutrients up and down the tree. As they bore and tunnel through the tree, they affect the food translocation system of the tree, often causing massive die-off from the top down. This happens because the top of the tree can no longer get food, as the tree's transportation systems have been compromised. In turn, this often causes new green shoots to start growing lower, as this is likely as far as food is able to be moved up the tree. Additionally, D-shaped exit holes are often formed from when the insect exits the trunk of the tree to feed on the green foliage once again. These holes are a sure sign of EAB, though they are hard to spot as they often occur higher up in the tree.

Is The Tree Worth Saving

Treatments are not a guarantee that the tree will be saved. Even if it was a guarantee, not every Ash tree in Fort Collins might be worth the time, energy, and expense of saving it. So, take some time to analyze your tree, and only treat trees that are of value. Examples of valuable trees are perhaps ones that provide energy savings in terms of shading your house from the sun or shielding it from the wind. Trees can also be of some sentimental value. When analyzing your tree, take into consideration things such as age or other potential damages to the tree. If your tree is old enough that it may have to be cut down in the near future, or if your tree has any injuries such as cracks or anything that could potentially compromise the tree down the road, it might not be worth trying to save.

For example, this tree to the right has a large crack down one of its major branches, making it likely not worth saving, as the integrity of the tree is largely compromised.

How To Treat Your Tree

One option is to apply a drench to the bark. Treatment such as this is systemically drawn up through the tree, warding off any threatening insects.

Another way is to use an injection system. This way is the most effective way and is our recommendation when trying to save a tree. This treatment uses compounds and chemicals that are only available to certified, licensed arborists, so contact us or get in touch with a trusted, local tree service provider. This injection system works by injecting a chemical directly into the base of the tree. Imagine an IV for your tree. The tree automatically soaks up the chemicals that are fed into its base within in a matter of 20-30 minutes, being distributed to every part of the tree through the trees translocation system. Within 12-24, the treatment will reach the extremities of the tree, protecting it from the Emerald Ash Bore for up to 3 years.

It is also possible for homeowners to treat the trees themselves. Bath Garden Center & Nursery carries a product called Bonide Tree & Shrub, which is a systemic action treatment. This product requires treatment of the soil around the tree. The tree will soak up the compound and transport it to the top of the tree to ward off any incoming insects.

Though this can work, there are some factors that do need to be considered, such as if the treatment will be as effective, how long the treatment will last, or if the treatment will be properly applied. Sometimes it can be difficult for a homeowner to administer the treatment correctly, or know if the tree is actually worth saving. All these factors are very serious and can result in the death of the tree and even damage to the surrounding environment if treatment is not handled and administered correctly.

So, please be sure to always consult your garden centers and nursery professionals before using any treatment. The health of your tree depends on using an effective treatment, and it is also good to be aware of other considerations you must take into account before applying any treatment.

If you would like to watch a video of our certified arborist treating an Ash tree here on Bath property, head to our YouTube! And feel free to contact us with any further questions. We are happy to help!


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