It is getting more and more difficult to find a live ash tree in Cincinnati. A vast majority of ash trees in Cincinnati and the surrounding area have been infested and killed. Treated trees remain alive and treatments have proven quite effective.
Research is being done in infested areas to determine if treatment frequency can successfully be reduced. So far that research is not promising and the every two year recommendation remains for Treeage insecticide, and annual treatment is recommended for other insecticides.
Despite the extent of ash devastation, we occasionally find ash trees seemingly thriving without treatment. To be sure, these trees are rare but they have been reported throughout infested areas. A few of these trees have even been found by me!
What are we to make of this? So far, no foundation for the immunity or resistance has been identified by researchers. Efforts are underway to catalogue and study these trees to try to find a common thread, perhaps even to turn the tide. However, these efforts are just beginning and no conclusions have been drawn. The chances that any one ash will survive without treatment are very small.
At Arbor Doctor, we keep up to date on research and we will certainly incorporate any changes in treatment protocol into what we do. For now, no change is recommended.