Emerald Ash Borer in Douglas and Shawnee County: Treat or Remove?

Emerald ash borer was first confirmed in Kansas in 2012 and is now established across the northeast corner of the state, including Douglas, Shawnee, Johnson, and Leavenworth counties. Untreated ash trees die. There is no version of this where you wait it out.

The decision in front of most homeowners here is narrow: treat this tree, or plan its removal.

How to tell if your ash has it

The symptoms show up in a specific order, and by the time the obvious ones appear the tree has usually been infested for two or three years.

Thinning that starts at the top. EAB larvae feed under the bark and cut off the tree’s water transport. The canopy dies from the top down, so the first sign is a thin crown while the lower branches still look fine.

D-shaped exit holes. About an eighth of an inch across, flat on one side. Round holes are a different insect. The D shape is diagnostic.

Woodpecker damage. Heavy woodpecker activity stripping patches of outer bark, called blonding, means the birds have found larvae under there. This is often the earliest visible sign.

Epicormic sprouts. Shoots pushing straight out of the trunk and root flare. That is the tree trying to grow new leaves below the damage.

S-shaped galleries. If bark comes off, the winding tunnels underneath confirm it.

Treatment works, on a schedule

Trunk injection is effective and well established. Insecticide goes directly into the tree’s vascular system and moves up into the canopy, killing larvae as they feed.

Two things people get wrong about it:

It is not a one time fix. Trunk injection lasts about two years, so protecting a tree means treating it every other year for as long as you want it. Budget accordingly.

It does not resurrect a tree. Treatment protects living tissue. It cannot rebuild a canopy that is already gone.

The line where treating stops making sense

The rough threshold used across the industry is canopy loss.

Less than about 30 percent canopy loss: treat. The tree has enough vascular tissue left to move the insecticide, and it will recover.

30 to 50 percent: a judgment call. Depends on the tree’s value, its position, and whether you want to fund treatment indefinitely on a tree that will never look the way it did.

More than 50 percent: remove it. Treatment at that point is spending money to delay an outcome, and the delay makes the removal more expensive.

Why waiting costs money

A dead ash is not just a dead tree, it is a harder removal.

Ash goes brittle fast once it dies. Within a year or two the limbs will not hold a climber’s weight, so a job that would have been a routine climb needs a bucket truck or a crane instead. The crane is the largest single line item on a residential removal.

So the untreated ash in your backyard gets more expensive every year you leave it standing, and at some point it stops being a scheduling question and becomes a hazard sitting over your roof.

What to plant instead

Do not replace an ash with another ash. Bur oak, chinkapin oak, Kentucky coffeetree, and hackberry all handle Kansas clay, heat, and wind, and none of them are on a pest’s menu the way ash is right now. Plant in fall if you can.

Get it looked at

If you have an ash in Lawrence or Topeka and you have not had it assessed, that is the next step. An arborist can tell you within a few minutes which side of the treat-or-remove line your tree sits on, and that answer is worth having before another season goes by.