by Dave Scharfenberger, Board-Certified Master Arborist WI-0131B
Emerald ash borer (EAB), one of the worst insects of all time, is threatening Wisconsin trees. Over 17 million ash trees have been cut down in Michigan, Ohio and Indiana due to this insect. Many authorities are concerned that EAB could wipe out every ash tree in North America! EAB will kill any kind of ash (Fraxinus) species even if they are perfectly healthy and vigorous. With ash making up 30% or more of our urban forests, this presents a significant threat!
Treatment with Imidacloprid will protect ash trees! We have been using this product for ten years to protect birch and other trees from similar boring insects. When used as a preventative, this soil systemic insecticide does not need to be sprayed (avoids drift) or trunk injected (which can do damage) and does not affect other insects that are not feeding on the tree.
While EAB has not been found in Wisconsin, yet, Wisconsin Department of Agriculture officials concede that it could be here and we just have not found it. For this reason, we at Wachtel are recommending people protect key ash trees now. Ash trees that are shading houses, patios or are solitary key trees in a yard are candidates for protection. This is not something to do for all ash trees. For example, with young trees it may be more cost effective to wait and replace them if they become infested. Our Certified Arborists can help you determine which trees to protect. If you are already treating your ash tree for plantbugs & leafhoppers you are protecting it from the borers, too!
The advantage of protecting now is that this treatment is best at controlling young stages of the insects and needs to be in the trees before the insects start to attack. Beginning treatment after insects are active in an area will lessen chances of success with Imidacloprid and will require a more expensive trunk injection to clean larger borers out of the tree.
Work in infested states is showing Imidacloprid to be 80-85% effective. Treatments will have to be done every year to maintain the protection. Be cautioned! The State of Wisconsin may cut down all ash trees within a half mile of the first EAB discoveries in an effort to delay infestation (this will depend on many factors). Removal will be done whether you are treating your tree or not! While treatment can be a risk due to this, the number of eradication zones are likely to be very few. Remember, early prevention works much better than late control.
Don’t delay. Now is the time to take action if there are key ash trees that you would like to protect. Our Certified Arborists at Wachtel can help you lessen the impact of this devastating insect on your valuable tree resource.