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Posted April 16, 2015 in Web Exclusives

(JOHNSTON, Iowa) —- On Wednesday, Iowa officials active in tracking and combating the spread of Emerald Ash Borer announced that the deadly tree pest has been found near the Des Moines metro.  EAB has been positively identified in a residential tree in the southeast corner of rural Dallas County, according to the Iowa Department of Agriculture and Land Stewardship, making this the twenty-first county in Iowa where this invasive beetle has been found. EAB kills all ash tree species and is considered to be one of the most destructive tree pests ever seen in North America.

It’s not if EAB arrives in Johnston, it’s when. Approximately 18% of trees in Johnston’s public spaces are ash trees. The density in several neighborhoods is even higher and the loss of all of these trees will have both a physical and financial impact on the neighborhood.

The city has 2,000 ash trees on city property and hundreds more on private property. The city has been taking a proactive approach in dealing with EAB since 2013. We have already removed more than 200 vulnerable ash trees on city property. The majority of the trees removed were in Green Meadows, near Crown Point Community Center, in Dewey Park, and on city right-of-way. All of these trees were considered stage four, vulnerable trees that were susceptible to EAB. In 2013, we added the position of Urban Forest Crew Leader to lead our efforts.

For every ash tree on public property that the city is removing, (and we have removed more than 200 already) we are replacing it with at least one healthy tree of a different species. Our plan is to replace more trees than we are removing. We will begin treating about 45 healthy ash trees this Spring in the hope that the borer will not attack the treated trees. This method has been very successful in healthy ash trees.

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 that you develop is to diversify your tree selection. Multiple species and ages are essential to a healthy environment.

If you have an ash tree on your property:

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

TRUNK INJECTIONS 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.

SOIL DRENCHES – Soil drenches typically take 4 to 8 weeks to absorb and are not as practical as trunk injections because of excessively wet soils, compacted sites, or restricted surface areas.  Do not make soil applications when soil is saturated or frozen.  Soil injections should be made within 12 to 18 inches of the trunk, and the solution placed 2 to 4 inches beneath the soil surface.

CANOPY SPRAYS – Canopy sprays are not recommended because of limited effectiveness, the need for special equipment, spray drift, and  possible adverse effects to non-target organisms.

TREE REMOVAL – 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.

Please contact Parks Director John Schmitz if you have any questions about city trees or the treatment of Emerald Ash Borer.  Schmitz can be reached at 515-727-8091 or at

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