Should “YOU” use
Insecticides for Emerald Ash Borer?
Healthy ash trees that have been protected with insecticides
growing next to untreated ash trees killed by EAB.
With the new metallic green resident in Wisconsin, “ The Emerald Ash Borer”, we are trying to help our customers weigh the benefits of treating trees and putting Ash Trees into a priority of value. This can be more difficult to quantify than the costs of preventative treatment. Landscape trees typically increases the property values, provides shade and cooling, and contributes to the quality of life in a neighborhood. Many people are sentimental about their trees. These intangible qualities are important and should be part of any decision to invest in an EAB management program.
If you know your tree is already infested but is still relatively healthy and it is high priority tree in your yard, for example it shades your very sunny deck, than you may want to treat it even though it is infested. If it has lost more than 50 percent of its canopy, it is probably too late to save the tree even if it is a priority tree. Most studies show it is best to begin using the insecticide while ash trees are still relatively healthy. This is because most of the insecticides used for EAB control, act systemically — the insecticide must
be transported within the tree. In other words, a tree must be healthy enough to carry a systemic insecticide up the trunk and into the branches and canopy. When EAB larvae feed, their galleries injure the phloem and xylem that make up the plants’ circulatory system. This interferes with the ability of the tree to transport nutrients and water, as well as insecticides. As a tree becomes more and more infested, the injury becomes more severe. Large branches or even the trunk can be girdled by the larval galleries. Studies have also shown that if the canopy of a tree is already declining when insecticide treatments are initiated, the condition of the tree may continue to deteriorate during the first year of treatment. In many cases the tree canopy will begin to improve in the second year of treatment. This lag in the reversal of canopy decline probably reflects the time needed for the tree to repair its vascular system after the EAB infestation has been reduced by the insecticide.
At sites where infested ash trees have been treated with a soil drench for 3 years, about half of the trees survived and look very healthy; the other half have died. These trees were heavily infested when the test began. Better 
results are possible if treatments begin a year or two earlier.
Research results indicate that the soil drench provides excellent protection for small ash trees
(less than 6 inches in diameter at breast height) in the first year following treatment, but larger trees may require two years of treatment before they are protected. Therefore, it is important to try to begin treating large trees before they become infested. Treatment must continue each year.
The tree drench products have Imidacloprid as the active ingredient. Label instructions say to use 1 ounce of the insecticide for every inch of distance around the tree trunk (circumference).
Applications should be made in Spring or Fall. Always read the instructions on the label and purchase from a knowledgeable dealer that can help guide you with the specifics for your climate, and varying factors in your yard.
In the gallon size most drenches that are applied at the base of the tree mixed with water are approximately .31 cents an ounce. A tree that was five feet in circumference would be 60 inches around, which would require 60 ounces of drench, at 31 cents = $18.60 a year. It is a simple and safe application easily applied by most homeowners and is a viable control if applied correctly.
So lets greet our new resident with a nice Imidacloprid cocktail.
For more information visit: www.emeraldashborer.wi.gov
