Emerald Ash Borer

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Emerald Ash Borer Response Plan.  Emerald Ash Borer (EAB), an invasive beetle that kills all species of ash trees, has been confirmed in Story County. With EAB confirmed in nearby communities, the future for ash trees looks uncertain. To be camden ash cropped 2prepared for the arrival and to slow the spread of this destructive insect, the City of Ames is pursuing an Emerald Ash Borer Response Plan that balances public safety with a commitment to replanting trees on public land.

There are more than 2,300 public ash trees in City right-of-way, in maintained areas of City parks (including along paved trails), and at City-owned facilities. Ash trees represent 16 percent of all public trees in Ames, which is higher than the 10 percent recommended for optimum diversity.  Map of Ash Trees on Public Property 

The Ames City Council approved the EAB Response Plan to extend the environmental, social, and economic benefits of ash trees, and to increase the diversity of the urban forest, while being fiscally responsible to Ames citizens. The plan pursues a phased treatment and removal process for public ash trees. In the first five years, a predetermined number of ash trees would be removed based on public safety, tree defects, size, and costs. The annual removal process would spread costs over a longer time period, allow staff to reevaluate the plan regularly, and limit the visual impact on streets lined with ash trees. Some ash trees will be treated, but only to keep EAB from killing the tree before it can be removed.

Although EAB will have a major detrimental impact on our community over the next several years, this challenge also presents Ames with an unexpected opportunity to bring greater diversity to the public trees in our urban forest. Through the one-to-one replacement program, a variety of saplings will be planted at a size of 1-1/2 inch, which is optimal for establishment and survival of new trees. Since most tree removals will occur during the winter, there will be a time gap between removals and the replanting of new trees.  Care and Watering Guidelines for Newly-Planted Trees

EAB photo by Eric R. Day

What is Emerald Ash Borer?  EAB is native to Asia and was likely introduced into North America via cargo ships or planes. The beetle is bright metallic green in color and is visible to the naked eye, but small—about the size of Abraham Lincoln’s head on a penny. The adult beetles eat ash foliage but cause little damage to the tree. It is the larvae that cause destruction. Larvae feed on the inner bark of ash trees, preventing delivery of water and nutrients to the tree, causing it to die.



What Can Property Owners Do?  The EAB strategy is primarily geared toward trees on publicly-owned property; however, homeowners can also help prevent the spread of the insect on their property by observing the following suggestions:

  • Do not move firewood across county or state lines. According to the Iowa Department of Natural Resources, the spread of Emerald Ash Borer into uninfected areas has been done primarily through the movement of firewood.
  • Identify ash trees on your property and watch for signs of Emerald Ash Borer. EAB, to date, has been found only on ash trees. Only those trees in the genus Fraxinus are ash trees. A common misconception, due to its name, is that a mountain ash is an ash tree. However, the mountain ash is in the genus Sorbus, and therefore is not an ash tree.
    Ash: 5 to 7 leaflets on a compound
    leaf (bud at the base of the stem)
    ash tree leaves
    NOT an Ash
     not an ash

    After identifying an ash tree, watch it for signs of decline, such as the top of the tree dying off, spindly sprouts growing from the trunk or roots, “D” shaped exit holes, and increased woodpecker activity. To confirm the presence of EAB in a tree, peel back the bark and look for the larvae, which is whitish in color with no prolegs and bell-shaped segments.
  • Contact your local extension office or professional tree service to discuss options for treating, removing or replacing your ash trees. If your ash tree is healthy, in a good location, and provides useful shade, there are chemical treatments available. However, to prevent ground contamination these chemical treatments have per-acre limits on the amount that can be used. Hiring a professional tree service is the best way to ensure the proper amount of chemical is used. Treatments that involve spraying a tree will not work, as they only kill the adult beetles and not the larvae, which cause the damage.

Additional Emerald Ash Borer Resources