Ash Trees On Your Property

What is Emerald Ash Borer?

Emerald Ash Borer (EAB) is an exotic beetle discovered in southeastern Michigan in 2002. This larva feeds on the inner bark of ash trees, disrupting the ability to transport water and nutrients. Most trees remain relatively stable after they die, but ash trees lose moisture internally and begin to fall apart relatively quickly. The flattened, creamy white larval stage feeds below the bark of ash trees and cuts off all nutrients to the tree and kills it. Adult borers are small, elongated oval beetles that are metallic green in color. This insect colonizes the top of the ash tree first, then moves down the tree. The tree's inability creates a public nuisance and can cause a hazardous situation. 

There are absolutely no restrictions on how you may handle treating (or not treating) an ash tree on your private property. The Johnston Parks Department, however, is happy to assist you in preparing for EAB with guidance from the experts at Iowa State University Extension & Outreach.

What Can I Do As A Homeowner?

The first thing that all homeowners should do is assess the health of their ash tree(s). If property owners have any trees that are stressed or unhealthy, now is the time to consider the possibility of removal. These trees will be more susceptible to EAB when it arrives. It also gives a little more time for new trees to grow. The key to any plan you develop is to diversify your tree selection. Multiple species and ages are essential to a healthy environment.

When To Treat Your Trees?

The window for treating your ash tree with a trunk injection is mid-May to mid-August. If a Johnston property owner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation, they should have landscape and tree service companies bid on work, review the bids and treat during the recommended treatment time. 

The State of Iowa will continue tracking EAB's movement on a county-by-county basis. Before a county can be officially recognized as infested, proof of a reproducing population is needed, and an EAB must be collected and verified by USDA entomologists. So far, there are no confirmed cases of EAB in Johnston.

Tree Removal?

The City of Johnston recommends trunk injections in healthy ash trees because injections are absorbed and distributed throughout the tree quickly (typically in 1 to 4 weeks) and are very effective. Research has shown that tree injections are tolerated in healthy green ash trees, especially if treatments are applied once every two years, small volumes of product are injected, and injection holes are small and shallow. Rotate annual trunk injections with other management options to decrease the possibility of long-term damage.

Removal of your ash tree may be necessary if it appears damaged, unhealthy or susceptible to EAB. Determine if your ash tree has EAB signs and symptoms by calling a trusted tree and landscaping contractor.

Need Help?

A great resource for figuring out what to do is Iowa State University Extension and Outreach. Visit their website for more information.

You may also reach out to the City of Johnston's Parks Department for help at 515-727-8091.

These links also offer good guidance:
EAB Treatment Options
EAB Insecticide Label Guidance (PDF)
Protect Bees from Pesticides (PDF)
Avoid the deadly risk of dying ash trees with timely removal