First, Some Emerald Ash Borer History…
In Michigan, where this insect made its first appearance in the United States, the Emerald Ash Borer ravaged the state and killed every Ash tree that had not been properly treated within about 9 years. The Ash trees that were saved in Michigan are now on a reduced ‘maintenance’ program. We had expected Illinois to follow suit and thought, as we’re sure you could understand, that it should naturally take about the same amount of time to reach that point in Illinois. We assumed that by now, just over 9 years after the Borer made its way down to Illinois, that we would have been able to reduce our treatment program to a maintenance level as well. Unfortunately, we haven’t been able to recommend that as of yet. Why is that?
There was a far larger population of Ash trees here in Illinois than there originally were in Michigan. At the time, there was no apparent reason to consider the difference in the number of Ash trees per state. However, once 2016 got here, which was the 9th year of the infestation here in Illinois, it was evident that there are still thousands of untreated Ash trees around us that hadn’t died yet. Why the difference? In our opinion, and in the opinions of noted Master Arborists, it’s because there are so many more Ash trees here in Illinois. So, it is taking longer for the insects to kill them all. When there are more Ash trees for the Ash Borer to choose from, it means fewer insects per tree, thus delaying and dragging out the dying process.
Please notice the photo that we included which was taken this week. It shows three Ash trees in an office park on Warrenville Road just a few traffic lights East of Naperville Road. If you pay attention as you’re driving around, you’ll notice that there are still untreated Ash trees such as these all over DuPage and Kane County. They are in homeowner’s yards, on commercial properties and in our extensive and beautiful Forest Preserve system. As long as Ash trees exist that have any live growth on them at all, they are capable of supporting the Emerald Ash Borer population. One would think that the folks who own these damaged, dying trees, and who have chosen to not treat them, would realize that they would inevitably die and would remove them for aesthetic appeal if nothing else. Unfortunately, for whatever reason they are delaying removing their trees, so these Ash trees still stand continuing to put everyone else’s Ash at continued risk.
We do not have a more definitive answer as to when we will be able to reduce the treatment program against the Emerald Ash Borer but for the reasons just explained, we must stay with the current program. The insect is definitely on the downhill slide but we just aren’t there yet.