EAB Treatment Should Continue

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.

ash trees with eabPlease 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.

Before and After Tree Treatment

We wanted to share some photos of before and after treatment.  We think you’ll agree they’re pretty remarkable. In the first two photos you see an absolutely enormous Ash tree. This tree is probably 200 years old, or older, with a trunk diameter just short of five feet across. It hangs over and shades the entire back of our customer’s house and stretches out over the back yard. The tree is spectacular and adds tremendous value to the property.

In 2013, we were contaash tree before eab treatmentcted by the owner of this tree, concerned about its obviously weakened condition from the Emerald Ash Borer, as shown in the first photo. You can see by looking at the trees in the background of the first photo, that this tree should have been fully foliated when this photo was taken, as those other trees were.

We gave this potential client a 30% chance, maybe less, of saving this tree but this tree owner said if there is any chance at all, he wanted to try.

ash tree after eab treatment

After 4 years of treatment, you can see how it looks today in the second photo.

Needless to say our client, and we, are thrilled over the result.


To date, we have saved over 94% of the Ash trees that we have set out to save. The only exceptions are trees where treatment was started later than would have been optimal or where there are horrible soil conditions such as too much clay or too wet of an area. These other stress factors, coupled with the constant onslaught that these trees are under from the Ash Borer, were just too much for those trees to overcome.


magnolia tree before treatment

magnolia tree after treatmentIn the second set of photos is a Magnolia tree. The first photo shows the tree in a very weakened, yellowing state. Yellow leaves occur when a tree is lacking necessary nutrients to keep its leaves green. This yellowing can be caused by insects sucking the nutrients out of the tree and/or poor soil conditions. Yellowing leaves are an indication that the tree only has a few years left to live if left ‘untreated’.

In the case of this tree both Magnolia Scale insects, as well as a small plot of soil in which to grow (sandwiched between the house foundation and a driveway), were the cause of its trouble back in 2011. In the second photo you can see the tree today, after six years of treatment. It is obviously thriving and its natural green color is back – thanks to a tremendous reduction in the scale insect problem and proper Root Fertilization.

Now, of the hundreds of Magnolia trees that we treat, we have a few trees in certain neighborhoods that are not responding as well to our treatments against the Magnolia Scale which is plaguing these trees all over our area. Scale insects, whether it is Magnolia, Lecanium, Cottony Maple or Euonymus Scale, are difficult to control. It often takes a few years to get the problem under satisfactory control. Why is this? Because Scale insects are masters at developing resistance to pesticides. The problem is that we don’t know which products they have learned to resist until we see the result the following year. Once we see that resistance might be an issue, we have to switch to different products to get control. Going forward, starting with treatments this coming Fall for this problem, we plan on rotating pesticides much more frequently.

Emerald Ash Borer – Treatment

Below you will see two photos of the same Ash tree. The photo on the left was taken in 2014. (Notice the totally dead Ash trees in the background of this photo.) The photo on the right was taken a few days ago.

ash tree   ash tree treated for EAB








It is evident that the Emerald Ash Borer (EAB) population has begun to subside in this particular neighborhood and that our customer’s tree is making great strides at recovery now that there are fewer borers attacking it.

Ash trees under treatment may appear stressed and look like they are starting to decline even though you are having them treated. This is normal until the pressure from the insect completely subsides and the tree can begin to heal internally and recover. While this may be the case in ‘most’ instances, it will unfortunately not be the case in ‘all’.

Yes, we have lost some Ash trees – 4% to date.  In those cases the client either started treating them too late or there were additional stressors on the tree besides the constant ongoing attack from the Emerald Ash Borer.

What happens is this….

Even though you are treating your Ash, the female Emerald Ash Borers in the area continue to fly to Ash trees and deposit their eggs on the bark. After all, they do not know that the tree is undergoing treatment. The little ones hatch and immediately begin to burrow into the bark to begin feeding inside the tree, obstructing the sap flow. The products that we injected into your tree then work to kill them before they can reach maturity. Even though we kill the borers while they are small, a tree may have thousands of them burrowing inside. They still cause some damage, which is why the tree appears stressed during its treatment. Once the pressure from the insect subsides, the tree will do all it can to repair itself to make a comeback.

We mentioned that we have lost about 4% of all the trees that we are treating. Why?  Once people heard about the EAB situation and then realized they had an Ash tree on their property, they may have begun treating later than others. These trees with later starts are more at risk than those that had started treatment earlier. Unfortunately, even a few of the trees that we started treating earlier have gotten to the point where we have had to recommend ceasing treatment. In all of these cases, there have been additional stressors that have contributed to this unfortunate recommendation. Some have been in ‘wet zones’ where drainage is poor. Some have been in unbelievably poor, heavy clay soil. Some of our clients routinely use ‘Roundup’ herbicide to kill weeds which is not supposed to affect trees but we have discovered that as the weeds die and decompose, the tree roots pick up the herbicide and it can stress or even kill the trees. It is known that most parkway trees are in poor soil as they have notoriously heavy clay content to buffer the road. While we have managed to save most of the parkway trees that we treat, it is the parkway trees that make up the vast majority of the total 4% that we’ve lost to date. Not only is there clay in the parkway but the trees also have diminished root systems supporting them because the street itself limits the tree to a smaller root system than it would normally develop, since roots cannot live under asphalt or under your concrete driveway. If you combine those factors with the constant onslaught from the insect, sometimes the tree is just not able to overcome all of those negative influences.

In instances such as this, only time and the tree itself can let us know if it will make it through this devastating situation.