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Emerald Ash Borer

By Neil Peterson

Last Updated Aug 1, 2011 12:12:03 PM



Emerald Ash Borer was first recognized in Michigan in 2002. It's likely the insect was brought through some type of shipping and had been establishing in the Lower Peninsula for at least a decade. Since that point, it has been spreading throughout the Midwest. The spread of the insect has been greatly facilitated by humans, especially the transport of firewood.

EAB is a nonnative wood boring beetle from Eastern Asia. It feeds exclusively on true Ash trees (the genus Fraxinus) and as with many introduced species, it has few animals which predate it. To further add to the depth of the situation, in many urban and suburban situations, Ash trees are both highly prevalent and many are already sick or diseased. Although definitive numbers are still hard to calculate, it is estimated that between 5 and 25 million ash trees have already been killed by the borer.

So what does an infestation look like? First-positively identify the tree. In the greater Rockford area EAB has been confirmed, but is so new, it isn't likely trees have died yet. Damage typically occurs over several seasons. It begins in the top third of the tree as dead branch tips and progresses downwards. The tree will also begin to sucker or sprout from the base and the sides of the trunk. Depending on tree health and infestation, trees usually die in 3 to 7 years.

Some good news: the insect can be treated; however, it needs to be done annually and is cost prohibitive. The only approved treatment method is the chemical SAFARI used with a bark penetrating agent (PENTRABARK). It's applied to the trunk of the tree from the base to a height of six feet. For homeowners, the recommendations are to remove all but the most important Ash in the landscape, and plant new trees. After the new trees have attained some size, cease treatment and remove the remaining Ash.

It's a very bleak situation reminiscent of the American Elm and Chestnut Blight before that. In some neighborhoods, Ash account for 95% of the canopy and their loss will be devastating. It’s a strong lesson in the absolute need to plant a diverse selection of trees. We are happy to assist you with any further information, just email Neil@nystromsnursery.com