Emerald Ash Borer Update

The emerald ash borer was first found in Lawrence in 2015, Topeka in 2017, and Osage county in 2022. We put out an initial article (https://wellnitztreecare.com/emerald-ash-borer-eab/), but we want to give you more info on this destructive beetle. We are seeing a lot of misconceptions/misinformation surrounding this invasive pest. Specifically:

  • Why should you care
  • How to identify an ash tree
  • Is your tree a good candidate for treatment
  • When to treat
  • How to treat
  • When is it too late to treat

Emerald Ash Borer

Emerald Ash Borer

We are seeing a lot of ash trees in very poor conditions all over Lawerance in SE and SW Topeka. We don’t want you to kiss that ash goodbye before you are ready!

Why care about Emerald Ash Borer

Impact of Emerald Ash Borer

For simplicity lets really drill down on just one community. According to the Topeka Forestry Department, there are approximately 3200 ash trees in city parks and along streets. Unless something is done, every one of those trees will die from emerald ash bore. Assuming an average cost of $700-1000 to remove each tree, that is somewhere between $2-3.2 MILLION to have those trees removed! Dead ash trees must be removed because they become very brittle and dangerous once killed by the emerald ash borer. BUT we are still only talking about street trees! What about all the trees on private property?!

Ash in Kansas

The Kansas Forest Service states that Ash trees are the third most common tree in Kansas by volume! They estimate there are 52.5 Million ash trees, 93% of which are located on private lands. Based on our own records, we estimate at least 1 in every 6 properties in Topeka has at least one ash tree. This number is still underestimated because it only includes properties that we bid a service on an ash tree. It does not include properties with ash trees who declined to do anything to that tree. That’s a lot of trees that could die, BUT they don’t have to! There are treatment options and the cost of the treatments is far less than the benefits derived from the trees. According to Powell Gardens, our local ash community is worth $4.5 BILLION calculated by stormwater runoff sequestration, pollution reduction, cooling properties, and other benefits.

Non-street Ash Trees in Topeka

I acknowledge I am going out on a pretty thin limb as far as my analysis goes, but let’s look at this another way. If we know there are approximately 3200 street trees in Topeka but that only makes up 7% of the ash trees because 93% are on private property, then there are over 40,000 ash trees in Topeka! Assuming a $1000 dollar removal cost per tree (this is probably low because many of these trees will be in back yards and over houses which will increase costs) we are looking at a $40 million cost to the community plus the loss of all the other benefits the ash trees were providing.

How to tell if you have an Ash

It is important to determine if you have an ash tree because if you don’t have an ash tree then there is no risk of emerald ash borer. So how can you tell if you have an ash tree? Simple.

Ash trees have:

  • Opposite branch/ leaf attachment
  • Compound leaves with 5 to 9 leaflets (Black and blue ash have 7-11 but they are much less common)

Ash tree id for ash borer

You can tell the difference between a simple leaf and a compound leaf by the bud location. This is a compound leaf.

Some common look-a-likes are pecan, walnut, elm, shagbark hickory, and box elder. Other than the box elder, all of these trees have alternate bud attachment. A box elder has opposite attachment but it will only have 3 to 5 leaflets and those leaves will have coarse teeth where an ash has a smooth or finely toothed edge.

Ash vs pecan ash borer

Ash tree on the left and pecan tree on right. Notice the opposite bud attachment on the ash stem and alternate bud attachment on pecan.

Is Your Tree a Good Candidate

Unfortunately, some trees are just not worth the time, effort, and money to save. These trees are typically already in decline from the emerald ash borer or some other condition that would limit its life expectancy. Fungal pathogens, abiotic damage, poor location, etc. may all be cause for forgoing treatment. If your tree is not a good candidate for treatment the best option is to make a plan for removal. If emerald ash borer is present in the area it is better to take trees out sooner rather than later. This is because trees attacked by the ash borer become weak and dangerous to remove increasing the risk for everyone involved. When the risk goes up, so does cost.

Good candidates for treatment have:

  • Full canopy
  • Zero or few pests
  • Proper placement in the landscape
  • Good structure
  • High value (if there is a good tree but it is in the back 40 of a property it may not have high value)

If you are not sure your tree should be treated contact us and we can help you determine what is the best course of action for your tree/trees.

This tree was a good candidate…until it got hit by a car.

When to Treat Emerald Ash Borer

Ash trees should be treated if the presence of ash borer is within 15-30 miles of if you are in a quarantined county. For the Lawerence, Topeka, and now Osage county areas, that’s everyone! Applications are best made as soon as ash leaves emerge. This allows the chemical to get through the tree before the adult beetles emerge and begin feeding on leaves. However, applications can be made anytime between May and September.

Emamectin Benzoate

The most effective treatment for emerald ash borer is a direct trunk injection with an Emamectin Benzoate product. This treatment provides the longest-lasting (2 years) control and works on all sizes of trees. This product needs to be applied by an arborist with specialized equipment.

Treating for Emerald Ash borer

Ash tree being treated with a direct trunk injection of Emamectin Benzoate.


Another common treatment is with a soil-applied Imidacloprid. This product is a one-year treatment, but it loses its effectiveness once a tree’s diameter is over 25 inches. This product is toxic to bees when used improperly. If applied to the base of an ash tree where flowers are nearby, there is the possibility of contamination and non-target pollinator death. This product is available over-the-counter and can be applied by homeowners, but it is important to note that over-the-counter products are less concentrated than arborist formulations.


The final common treatment is with a Diontefuran bark spray or soil drench. This product has the shortest residual, offering the least amount of protection. It also has the same risks as imidacloprid and can harm bees and pollinators if used inappropriately. The main benefit of Dinotefuran is it can move through an entire tree in as little as a week.

When is it too late

Once an ash tree has had about 30% of its canopy die-back due to the beetle, it is probably too late to treat the tree. This is because the insecticide is transported though the same areas where the insects are feeding. The feeding causes interruptions in the phloem and cambium from the roots to the canopy and the chemical cannot make it to the areas it is needed to be effective. The trees below are too far gone. A common symptom of emerald ash borer is the presence of shoots or suckers that appear low in the canopy or on the trunk.

Ash in decline from emerald ash borerEmerald ash borer tree
The ash on the top is pretty rough, the ash on the bottom is probably a year further advanced in its infestation.

Contact an Arborist

If you have questions or concerns feel free to contact us. We would be happy to come out and give you options for treatment or removal depending on your specific situation.

Wellnitz logo