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Emerald Ash Borer Confirmed for McDonough County


The presence of emerald ash borer (EAB) has been confirmed for McDonough County Illinois, with the initial finding coming from Macomb. EAB is a devastating exotic pest that attacks one of the most popular landscape trees in America, the ash tree. Unlike most native borers that only target dead or dying trees, EAB preys on healthy ash trees.

However, the presence of EAB in McDonough County is not isolated to Macomb. A local Bushnell resident notified Extension of what he suspected was EAB. Upon inspection of the sample, the EAB adult beetle was identified in Bushnell. Reports of suspect EAB signs are also coming in from Blandinsville.

How to manage EAB and its impact on your ash trees comes down to two choices: protect the tree with systemic insecticides or have your ash tree removed. Following are guidelines to assist you when weighing these two options.

Guidelines for Treatment:

According to retired Extension entomologist Phil Nixon, trees with up to 30-40% dieback have an excellent chance of survival with treatment, but with that much dieback, the tree may not be worth keeping aesthetically.

Preserving your ash tree - If you observe more than 50% of the tree's canopy living and intact, treating with insecticides is a viable option:

  • Ash trees with less than a fifteen-inch diameter at breast height (DBH) can be treated by homeowners using systemic treatments containing the active ingredient imidacloprid or dinotefuran. Imidacloprid is applied as a soil drench around the base of the tree and dinotefuran is used as a bark spray. Both treatments are annual applications. Make sure to follow all label directions.
  • For trees with a DBH greater than fifteen-inches, you need to hire a licensed applicator to make trunk injections of pesticides containing imidacloprid, dinotefuran, or emamectin benzoate. Imidacloprid and dinotefuran need to be applied annually, while emamectin benzoate provides two and perhaps even three years of protection according to studies from Michigan State University.

Removing your ash tree - If your ash tree has lost a majority of its canopy, contact a certified arborist to have your tree cut down. The University of Illinois Extension discourages treatment of trees that have lost more than 50% of their canopy.

The state has recently lifted the internal county quarantine zone, but it is still not permitted to move ash wood outside of Illinois state lines. (Moving firewood, in general, is a bad practice, so don't do it!) Contact your local officials for their landscape waste disposal site.

Do nothing – According to Phil Nixon, EAB poses a 98% mortality rate to ash trees. If your county is confirmed with EAB and you do nothing, the odds are obviously against you. However, a few ash trees, mainly white and blue ash, will survive.

A dead ash tree needs to be removed soon after death. Once deceased, ash trees degrade very quickly and run the risk of injuring bystanders and causing significant property damage as large limbs fall or the entire tree pitches over. Ensure the safety of you and others by removing an ash tree as soon as possible after its death.

With the presence of emerald ash borer in McDonough County, homeowners and city officials must consider costly treatment or removal of ash trees. With all this bad news, let's shine a light on EAB as an opportunity to plan a future tree canopy filled with a diversity of species which will add value to the communities of McDonough County. Please try to plant more than just maples!

University of Illinois Extension will be hosting a public meeting to inform community members on their options and address homeowner questions on EAB June 30 at 3 PM in Macomb. To register online visit http://go.illinois.edu/EAB or call Amanda Christenson at the Knox County Extension office 309-342-5108.


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