Emerald Ash Borer: Insecticide Options for Protecting Ash Trees and Their Effectiveness

Although, to date, the emerald ash borer (EAB) has not been discovered in Wisconsin, many questions have been asked by homeowners and Green industry professionals regarding the capability and need of insecticides for protecting ash trees from EAB. There has been much confusion surrounding the question of whether insecticides are an effective management option for EAB. Research and experience has shown that insecticides can protect ash trees from being killed by EAB. However, success in not guaranteed! In some university trials, insecticide treatments were effective, but in other trials the same treatments failed. Some studies conducted over multiple years revealed that EAB infestations continued to increase despite ongoing treatment programs. Insecticides are not effective in eradicating EAB infestations, which is why they have not been used as an eradication tool by the Cooperative EAB program in other states. Research suggests that best control can be achieved when insecticide treatments are started in the earliest stages of infestation before visible symptoms are present or possibly the year before trees are infested. It is important to understand that insecticide treatments must be repeated each year. As a result, in some cases, it may be more cost-effective to remove and replace the tree. There are several insecticide options available for those people who want to treat their trees. It is important to understand that controlling wood-boring insects with insecticides has always been a difficult proposition. This is especially true with EAB because our native North American ash trees have no natural resistance to this pest. Insecticide research programs are showing promise, but research on chemical control of EAB is still in early stages. Scientists from universities, government agencies, and companies are conducting intensive studies to understand the circumstances under which insecticide treatments will be most effective