Emerald Ash Borer
I have a 20-year-old "Autumn Applause" Ash tree that I have been treating annually with an imidacloprid soil drench to deter Emerald Ash Borers. So far, the treatment has been successful and I have seen no activity in any of the branches or trunk , such as the telltale "D" exit holes. I'm a bit of a tree fanatic, so I have observed many ash trees that have been ravaged by the borers and am familiar with the signs. I also fertilize the tree each year, and it remains healthy & beautiful. This year, I treated the tree on April 27th, but I had forgotten that and treated it again about a week ago. I use imidacloprid alone (not the Bayer combination product). Will two applications such as this harm the tree? I have since found my notes about the April treatment, but too late of course. Is there any benefit to two treatments? This is a really beautiful tree and I'd hate to damage it. Thanks in advance for your response!
Monroe County Michigan
Assuming you made each application of imidacloprid at the labeled rate, it's unlikely the additional treatment will have an adverse effect on the tree. If you've been getting adequate control with a single treatment, there is probably no benefit to a second treatment - and we don't want to put more pesticide in the environment than is needed for control.