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The next time you walk through your neighborhood, take note of the ash trees you see. They are popular shade trees that comprise approximately 20% of our urban forest. Due to the arrival of the emerald ash borer – an invasive insect native to Asia – each one of those ash trees is in danger.
Adult emerald ash borers (Agrilus planipennis Fairmaire) move quickly and the larvae eat ravenously. Tens of millions of ash trees have been lost in Michigan alone (where the borer was first discovered in 2002); millions of additional trees have been lost in the wake of the borer’s spread into Illinois, Indiana, Kentucky, Minnesota, Missouri, Ohio, Ontario, Pennsylvania, Quebec, Virginia, West Virginia, and Wisconsin.
Facts about Emerald Ash Borer:
- EAB attack all ash trees, regardless of the tree's health.
- Adults are small – 1/2” long, 1/8” wide – metallic green beetles.
- Larvae chew S-shaped galleries beneath the bark, cutting-off the flow of water and nutrients through the tree’s vascular system.
Visible Signs and Symptoms of an Infestation:
- Canopy dieback and suckers sprouting from the tree’s trunk
- 1/8” diameter D-shaped exit holes in the tree’s trunk and upper
branches
- Loose bark and vertical splitting of the bark
- Bark damage caused by woodpeckers
Since the Illinois Department of Agriculture announced the discovery of emerald ash borer in Kane County on June 13, 2006, surveys have revealed infestations throughout the Chicago metropolitan area. As a result, all northeastern Illinois counties are under a state-instituted EAB quarantine and a statewide quarantine was established by the USDA Animal & Plant Health Inspection Service.
The long-term forecast for Illinois’ ash trees is not promising; however, there are ways you can protect your ash trees from EAB.
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Fortunately, significant advances have been made in the management of emerald ash borer. According to research conducted by Michigan State University, systemic insecticide treatments can be up to 99 percent effective in stifling the spread of the pest.
Emerald ash borer (EAB) has been confirmed in every county throughout Chicagoland, which means that each ash tree in our region is at risk. As a result, homeowners have two options: either employ a “wait and see” approach or take advantage of treatments that are proving effective in combating the pest.
Research of EAB management is ongoing. However, of the treatments currently approved for use in Illinois, systemic insecticides are particularly promising. Systemic insecticides are dispersed by means of the tree’s vascular system. Because these products are carried within the tree, they do no harm to animals or insects that do not feed on your tree (e.g. birds, squirrels, or butterflies).
The two best means of treating an ash tree are:
- Annual soil injections of a systemic insecticide
- Biennial trunk injections of a systemic insecticide
Many factors impact a systemic insecticide’s ability to protect your tree. They include:
- The extent of EAB infestation within the tree prior to and during treatment
- The degree of EAB infestation in the vicinity of the tree
- The size of the tree
- The health of the tree
- The tree’s ability to distribute the insecticide throughout its
branches and leaves
Please Note: If an ash tree is heavily infested with EAB (exhibiting dieback in more than 50% of its canopy), it is less likely to benefit from a systemic insecticide application. In such a case, the best option may be to remove the tree and replace it with a non-ash species to help diversify the urban forest.
There are many factors to consider. The arborists at Autumn Tree Care Experts are ready to help you weigh the options. For more information, talk with your arborist by calling 847.729.1963.
For additional information – including up-to-date EAB quarantine maps – visit www.emeraldashborer.info
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