By: Keith Glaznap Certified Arborist WI-0678A
Wouldn’t it be nice if all questions had a simple answer? Life would be so much easier if all answers could be summed up in one word. Although there are no easy answers to emerald ash borer, hopefully I can help make your decision on what to do with your ash trees a bit easier.
Let me start with a couple of facts. We know that untreated ash trees are vulnerable to emerald ash borer (EAB). We also know that ash trees found to have EAB could still be saved if the borer population is low enough in those trees. (Note: Trees with >40% crown thinning are heavily infested and no longer savable)
The confusion usually begins with the following questions: When do I start treating my ash trees? Do the treatments work? How often will I have to treat my ash trees?
The answer to these questions may vary significantly depending on your circumstances. A search on Google, will reveal reports that are outdated along with some misinformation put out there by non-professionals. By the time you finish your search you may end up having more questions than you started with.
Based on current university research, I will explain what is now recommended by your Wachtel team to help protect your ash trees from EAB.
Where to start: Only treat the ash trees that you want to save. Determine which trees are the most important for your landscape and then have them assessed to determine if they are good candidates for treatment.
When to start: Once you have determined which ash trees you want to treat you should initiate a treatment plan as soon as possible.
Which treatments work:
Tree age insecticide: If any of your ash trees are within 15 miles of a known infestation and have not yet been treated or are already exhibiting signs of possible EAB activity, this is the product to start with. Tree age has thus far been proven to be the most effective product for helping to save ash trees with light EAB activity. Note: there are no treatments to save heavily infested trees.
Imidacloprid: If your ash trees are farther than 15 miles from a known infestation, do not exhibit signs of EAB activity or your ash trees have been getting soil injections of Imidacloprid already, then soil injections of Imidacloprid at the proper rate should be very effective at deterring EAB .
How often to apply:
Tree age insecticide: The Tree age trunk injection is effective for two years at which time you can either continue with those treatments every other year or switch to the less invasive method of yearly soil injections containing Imidacloprid.
Imidacloprid: These soil injections, applied at the proper rate need to be applied once per year each year.
So far all of the research indicates that these options are currently the best for your ash trees in the given situations above. As you can see, there are many different factors that help determine what is best for your tree. The key to making any of these methods work for you is to have a professional out on your property to assess your ash trees. Call your Wachtel Tree Science Certified Arborist today and schedule an appointment.