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MDC advises caution and education in responding to EAB

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Emerald Ash Borer Beetle

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D-Shaped Emerald Ash Borer Hole

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Emerald Ash Borer Damage

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Published on: Aug. 1, 2012

Kansas City, Mo. -- A destructive insect that kills ash trees, the emerald ash borer (EAB), has been confirmed in the Kansas City area and has expanded its range in the southeast Missouri Ozarks. Homeowners and property managers should be cautious and informed as they seek to protect ash trees.

“Don’t be too hasty,” said Wendy Sangster, an urban forester in Kansas City with the Missouri Department of Conservation (MDC). “Learn about the emerald ash borer and when it is appropriate to remove a tree and when it is not.”

Information about the pests is available at eab.missouri.edu.

Steps can be taken to protect an ash tree from the borers, and removing infested trees can slow their spread in a community. But homeowners should avoid costly and unnecessary tree trimming and removal or ineffective application of insecticides, Sangster said.

"Property owners should beware of scam artists offering tree services who are not professional arborists," she cautioned. "Beware of anyone asking for money up front or promising special treatments."

The adult emerald ash borer is a metallic green insect a half inch long and one-eighth inch wide. But it is the tiny larvae that are most destructive. Adults lay eggs on ash tree bark. The larvae emerge from the eggs and then chew through the bark and into the nutrient-carrying phloem layer beneath the bark. Larvae then feed on the phloem, creating S-shaped tunnels that eventually cut off the flow of nutrients within a tree. As more generations infest a tree, the tree eventually dies.

There are other native borers that damage and can kill ash trees, too. But they are not as damaging or deadly as the emerald ash borer. Correct identification of insect damage is necessary to avoid needless labor and costs.

A native of Asia, emerald ash borers were first identified in North America in Michigan in 2002. Since then, the borers have killed millions of ash trees in 16 states and two Canadian provinces. The adult borers can fly short distances. But their spread is believed due to people moving firewood from infested areas.

In 2008, emerald ash borers were confirmed in Wayne County in southeast Missouri. On July 25, the Missouri Department of Agriculture (MDA) announced that the species was found in two traps in adjacent Reynolds County. MDA announced that emerald ash borers were confirmed in Platte County in the Kansas City metro area.

Emerald ash borer infestations in the Kansas City area could potentially kill many street trees and shade trees. The borers are 100 percent fatal to all native ash trees regardless of age or size. However, these pests are not harmful to humans or pets. They will not harm wood structures. They do not kill any other tree species.

The initial confirmation of emerald ash borers in the metro area is in unincorporated Platte County near Parkville, Weatherby Lake and Kansas City, North. An alert arborist made the initial discovery. MDC foresters and state and federal inspectors are now surveying other sites for signs of the borers.

Steps the public can take include:

  • Identify if you have ash trees in your yard.Check ash trees for signs of damage. An indicator can be small D-shaped exit holes in the bark left by newly emerging adults. Under dead bark there will be S-shaped galleries or grooves left by feeding larvae. Information about signs and symptoms is available at eab.missouri.edu.
  • Anyone finding signs of emerald ash borer in Missouri can call the MDC Forestry Division at 866-716-9974.
  • Kansas residents can contact the Kansas Department of Agriculture at ppwc@kda.ks.gov or 785-862-2180.

Chemical treatments are available that can help prevent infestation by the borers. If a shade tree in a lawn is highly valued, property owners may want to choose that option. Most treatments are injected into trees or are applied to the soil.

However, under current drought conditions, treatments may not be effective because little moisture is moving in trees, Sangster said. Unless trees are routinely watered, chemical treatments can wait.

Tree trimming will not prevent damage from the borers, Sangster said. There is no immediate need to remove infested trees. Adult emerald ash borers emerge in the spring and are dead by mid-summer. No new infestations will occur until next spring.

But for any tree removal or preventative pesticide application, it is recommended that property owners contact a certified arborist that is trained and insured. A list of certified arborists is available at http://www.isa-arbor.com/.

The public can assist with slowing the spread of emerald ash borer.

  • Do not move firewood from one community to another. Purchase, cut and use firewood locally.
  • Do not move ash logs to other property, and burn or chip wood from infested trees. The wood needs to be finely shredded to less than one inch for two of three dimensions to kill borers.
  • Removing trees with known infestations can help slow the borers spread in a community.
  • Do not plant ash trees.

It may take several years for an infested tree to show signs of damage. For now, foresters are urging property owners to plant a diversity of trees and avoid a monoculture. That could include planting a new sapling near a currently healthy ash tree, in case the emerald ash borer problems spread.  

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