Emerald Ash Borer Information

Ash tree dying from Emerald Ash Borer

Frequently Asked Questions

By now you’ve probably heard of the Emerald Ash Borer, a non-native beetle that has killed millions of ash trees across North America since it was first identified in Michigan about fifteen years ago. Johnson County had its first instance of confirmed EAB infestation in 2016, found on the University of Iowa campus. Since then, damage to ash trees from EAB has shown up across Iowa City, Coralville, North Liberty, and elsewhere in Johnson County.


How does EAB kill ash trees?

The adult beetles feed on the leaves of the tree, but this causes little to no damage to the tree’s health. The life cycle that kills the tree is the larval stage - EAB larvae feed on the cambium layer under the bark in a serpentine pattern that cuts off the tree’s circulatory system. The tree is unable to transport water and nutrients when heavily infested. Generally, dead branches will first appear in the upper canopy, and it is common for the tree to sprout profusely in the lower canopy as water and sugars from the roots are unable to transport further up into the tree.


When should I treat my tree?

If you want to save your tree from the EAB, treatment works best BEFORE the tree is infested, while the whole tree canopy still appears to be healthy. Acorn Arborcare performs ash treatments beginning in May and through June and July, when the tree is best able to move the treatment chemical through its xylem. EAB is now well enough established in our community that you need to start treating your trees this summer if you want to save them and haven’t already.


Should every ash be treated?

No! Only good quality, healthy ash trees should be treated. Ash trees that are in poor health, have serious structural defects, or have a recent history of dropping large branches should not be treated, and should be removed instead. Acorn ArborCare also offers removal services, and replacement tree planting. Contact us to set up an appointment to discuss whether your ash tree is a good candidate for treatment or not.


Why should I treat my ash tree?

Trees provide economic, environmental, and health benefits to us humans, and your ash tree may have a lot of life left in it, if treated. Your ash tree may be reducing your energy consumption, providing habitat for lots of different types of wildife, making your yard a more enjoyable place to spend time, and improving the value of your home. The ISA certified arborists at Acorn Arborcare can help you weigh the benefits your tree provides against the costs of treatment so you can make an informed decision.


How do you treat ash trees?

Acorn ArborCare uses chemical injections that start by drilling small diameter holes around the circumference of the tree, and then inject insecticide into the xylem of the tree. We use a plug-less system that doesn’t leave behind any plastic plugs and minimizes injury to the tree.


Who will treat my tree?

Injection treatments for EAB need to be performed by a licensed pesticide applicator. John Borgen and Virginia Miller from Acorn ArborCare are both licensed pesticide applicators and ISA certified arborists. Contact us to set up an appointment.


Where can I read more?

The Iowa State Extension Service has lots of helpful publications for the general public to read. Find more here: https://www.extension.iastate.edu/psep/emeraldashborer.html