Ash borer hits hard; how to react

If you have an ash tree in your landscape, it’s either leafed out and looking pretty good, leafed out and looking somewhat thin, or not leafed out at all. A significant number of ash trees in the Miami Valley are showing symptoms of emerald ash borer (EAB) damage.

If your tree has barely leafed out, take it down. Once a tree loses more than one-half of its canopy, it won’t likely survive. If there is still a good 60-70 percent of the canopy remaining, you may be able to treat the tree this fall and keep it alive.

As you look around the Miami Valley, you notice quite a few dead trees, and it’s very likely they are ash. EAB has been in the area for approximately five years now, and we are really seeing the impact of this pest this year.

If you still have a healthy or fairly healthy tree, you can treat it and keep it alive. You will have to treat every year or every other year, depending on how you approach it.

If you do it yourself, you have to treat every year in mid-fall or mid- to late spring; the products available to homeowners only last a year. If you have a professional treat it, they use products that last two years.

Chemical drenches around the base of the tree with a product containing the active ingredient imidacloprid or dinotefuran are very effective in killing the borer and keeping the tree alive.

You can find these products at most garden stores and include the following: Green Light Emerald Ash Borer Killer (dinotefuran); Optrol, Bayer Advanced Tree and Shrub Insect Control, Bonide Tree and Shrub Insect Control, Ferti-lome Systemic Insect Drench, Ortho max Tree and Shrub Insect Control.

If you apply these products today, you may still get some control this year. These are systemic meaning the chemical is taken into the tree, killing the larvae feeding inside the tree.

Professional applicators have a product that lasts for two years (you will pay more) and others that last for a year. Many of these are trunk-injected and therefore, you have up to the middle of June to apply these.

And as always, read, read, read the label. In order for the soil drenches to be effective, the ground needs to be moist to facilitate uptake of the chemical. Also, make sure you use the correct amount for the size of tree that you are treating.

As more ash trees come down and people begin to replant, keep in mind the importance of planting a diverse tree canopy. There is a popular street in my hometown that has 58 ash trees out of the 115 trees on the street. I know of a campground in Port Clinton that has 125 trees and all are ash. Diversity is important so that when something happens to one species you still have a tree canopy.

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