By Donald R. Lewis
Department of Entomology
Iowa State University Extension

In early April the emerald ash borer was discovered near Victory, Wis., just across the Mississippi River from the Iowa-Minnesota border. The emerald ash borer (EAB) is a small, invasive beetle that has destroyed tens of millions of ash trees in states to the east. With the discovery of an EAB infestation within sight of Iowa there is a great deal of concern about what this means for ash trees in Iowa.

First, to emphasize the positive, EAB infestations have NOT been found in Iowa. Ongoing surveys by regulatory agencies have not been able to find any infestations. This includes tree inspections along the Mississippi River in Allamakee County across the river from Victory, Wis., as recently as last week.

EAB was first discovered in North America in 2002 near Detroit, Mich., after being accidentally introduced in wooden cargo crates apparently from Asia. Researchers have determined, though, that the beetle had resided there for 10 or more years before it was finally discovered. Other infestations have been found in Windsor, Ontario, Ohio, northern Indiana, northern Illinois, Maryland, western Pennsylvania, West Virginia, Wisconsin, Missouri and Virginia. Authorities conclude that most of the spread has been done by people transporting firewood, logs, lumber and nursery stock.

EAB destroys the ash tree by cutting the plumbing of the tree. Larvae burrow in the tree just under the bark and eat the active transport tissues, effectively girdling the tree. Infested ash trees usually die within two to four years of initial attack.

Dying ash trees attacked by EAB produce a distinct but not foolproof series of symptoms. At first the branches in the top of the tree will die, followed by shoots growing from the trunk and major branches. Adult beetles create one-eighth inch, D-shaped exit holes in the bark where they emerge from the tree. The bark of attacked trees comes loose, revealing winding, S-shaped tunnels on the surface of the wood. Again, these signs are useful diagnostic tools but they are not foolproof as other pests and maladies cause these same symptoms.

For the past several years Iowa State University Extension has been watching and learning from the experiences of infested states and offering updates and trainings about this serious pest to the public, tree care companies and arborists. All along we have been braced for the eventuality that EAB would find its way into the state. As our counterparts in other states have said, it's not IF the emerald ash borer invades your state, it's WHEN.

The impact of EAB has been devastating in other states and will be here as well. The cost of removing and replacing destroyed trees will be financially taxing, and the loss will cause a severe environmental impact as well. There are an estimated 88 million ash trees in Iowa, many of them in cities and neighborhoods. Loss of these ash trees may very well increase heating, cooling and watering costs for residential areas. Iowa estimates the cost from EAB will exceed $7.5 billion to remove dead trees and another $5 billion to replant.

ISU Extension has been working on control recommendations to help home owners and landowners decide if and how to attempt treatment that may protect valuable ash trees from this pest. I should emphasize that insecticide treatments for ash trees are NOT recommended in Iowa at this time. When the EAB is near you (a relative term but currently interpreted as a confirmed infestation within 15 miles of your property) it will be time to decide which ash trees are going to be treated with insecticide in an attempt to prevent attack. Treating is not 100 percent effective and even treated trees will be removed if your tree is in a regulated area.

In addition to ongoing general education to the public about EAB, ISU Extension will continue to provide updates on the distribution and management options for this new pest as information becomes available from the partnering agencies (the Iowa Department of Agriculture and Land Stewardship, Iowa Department of Natural Resources, USDA-APHIS and USDA Forest Service).

We also are beginning a series of specialized trainings in southeast Minnesota and northeast Iowa in cooperation with the University of Minnesota and University of Wisconsin and their corresponding state agencies. The special program is called "First Detector Training," a type of first responder program authorized and funded by the National Plant Diagnostic Network for dealing with invasive species. People trained as "First Detectors" will have special responsibilities in the effort to identify EAB activity as distinctive from other causes of tree decline and death.

Officials are continuing to develop response plans for the “three corners” area where EAB has been found. The first step will be to quarantine movement of hardwood firewood, ash nursery stock, ash timber or any other article that could spread EAB out of the infested area in Wisconsin. Minnesota has announced a state emergency quarantine of Houston County, across the river from the infestation, even though they have not yet confirmed an EAB infestation in the state.

The most important action for Iowans right now is to not bring firewood in from out of state. Also stay informed. ISU Extension along with other state and federal agencies has assembled information on many websites where you can learn more about the EAB distribution, infestation symptoms and control measures. A good place to start is with the national emerald ash borer website. www.emeraldashborer.info. And as always, please contact your local county extension office for more information.

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