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Save Your Ash - Protect Against the Emerald Ash Borer

The Emerald Ash Borer (commonly referred to as EAB) infestation has now spread beyond Minneapolis/St. Paul and into the suburbs. It was discovered at the Fort Snelling Golf Course and reported in Edina, South Minneapolis, Bryant Lake Regional Park and Hyland Park Reserve in Bloomington. The Shoreview neighborhoods also show that America's most destructive tree pest is on the move. Here's the information you need to arm your trees against this destructive invader. Accidentally imported from China, this beetle was first discovered in Michigan and Ontario in 2002. It quickly spread to Ohio, Indiana, Maryland, Illinois, Pennsylvania, West Virginia, Wisconsin, Missouri, Virginia, Quebec and in May 2009 it was found in St Paul, MN.

Adult EAB on Quarter
Adult EAB - Size Comparison with a Penny

It feeds only on ash trees, and has no natural predators. The adult is a slender, bright green, ½ inch long beetle that lays eggs on the bark from mid-May through June. Larvae burrow into the tree, feeding just under the bark from late summer to fall, making shallow serpentine tunnels that are visible if the bark is removed. The tunnels disrupt circulation within the tree and eventually kill it. Larvae overwinter and pupate within the tree, emerging the following spring through D-shaped holes.

The first year there are few visible symptoms. In the second and third years, the crown thins and the bark cracks over the tunnels.

EAB Damage
Thinning of the tree's canopy & visible tree damage




The tree usually dies the third year after infestation. Once the tree’s circulatory system is damaged by EAB, it cannot be repaired, that’s why prevention is so important. There are about 870 million ash trees in Minnesota, one of the largest concentrations of ash of any state. Not only are these trees abundant in our forests, but they are also an important component of our urban landscapes. Gertens recommends Bonide Tree and Shrub Insect Control to protect your ash from EAB.

Bonide Annual Tree and Shrub  
Bonide Tree & Shrub

Bonide Tree and Shrub Insect Control is mixed with water and then used to water the tree at the base, where as GreenLight Tree and Shrub insect control is a granular that you spread at the base of the tree. The tree then absorbs the insecticide and uses it against insects in much the same way antibiotics work against bacteria in humans. Each of these products is a simple, once per year application. You can apply prevention in the spring, summer and effectively in the fall too. In addition to treating your ash tree, we are also recommending planting young trees of various species near ash, so if they do eventually become infested with the borer the young tree will start providing a decent amount of shade by the time the ash tree has to be removed. Possible replacements include Maple, Birch, Elm, Linden, Hackberry, Kentucky Coffee Tree, Ginkgo, among many others.

If evidence leads you to believe your ash tree is infected with Emerald Ash Borer, please report it to your local county extension office. If you have any additional questions regarding these troublesome insects, feel free to stop by and chat with one of our lawn and garden experts or let us know on facebook.