Current Status of Emerald Ash Borer in Porter County

Emerald Ash Borer (EAB) is an unbelievably destructive insect that attacks and kills Ash trees.  To our knowledge, no species of the genus Fraxinus are immune to EAB.  Of Asian origin, this insect was first detected in the US in Southeastern Michigan in 2002.  However, based on our observation of EAB in Porter County, we believe those first insects must have arrived in Michigan several years prior to actually being detected.  This is significant, and we are writing this article to help you understand the impact this insect is havng on our trees and forests.

EAB is definitely well-established in and around Porter County, and we know that EAB has been in Porter County for several years, since approximately 2010.  The evidence of it's rampant destruction started to become painfully evident in 2012 and, especially in 2013.  Unfortunately, the worst has yet to be seen.

Surprisingly, some folks seem to be unaware of this problem, and we continue to have customers ask us if we think EAB will kill ash trees in our area.  The answer is YES, without any doubt.  It is already in advanced stages, and this will be significantly obvious in 2014.

Recently, there has been comment in the media about EAB and the impact of our extremely cold winter on this insect.  Some sources have reported that a signifcant percentage of the insects may have been killed by prolonged sub-zero temperatures.  This may be true, but only time will tell.

The problem is that so much damage has already been done to unprotected Ash trees that even if ALL the Emerald Ash Borer larvae were frozen to death, we will still witness a devastating mortality of Ash trees in 2014.  Remember that EAB was first detected in Michigan in 2002.  EAB had been in the Ash trees for several years before they began declining and dying.

As EAB becomes established in an area, the population approximately doubles each year for 5 to 6 years, or until ALL (100%) the Ash trees are dead.  The small emerald green adults emerge in late May to early June in NW Indiana.  The D-shaped exit holes made by those adults are unmistakable, but they are small, only the diameter of a ballpoint pen refill.  Those adult insects feed on the foliage of Ash trees for several weeks prior to mating.  Female EAB adults then lay eggs onto the bark of Ash trees, and the hatched larvae bore into branches and trunks and feed on the vascular tissue (xylem and phloem) just beneath the bark.  Their random feeding tunnels severe this vascular tissue, making it difficult, and ultimately impossible for water and nutrients to move from the roots to the leaves of the tree, and a slow death begins. 

In the first year, symptoms may be difficult to detect, but by the end of the second year, upper branches begin to die, and as the larvae move farther down the tree, disrupting more and more vascular tissue, the tree struggles to survive.  Eventually, the battle is lost, the tree dies, and the insect's life cycle becomes disrupted as the quantity of living Ash trees dwindles.

Currently, the homeowner's only line of defense is application of a neonicotinoid insecticide, such as Imidacloprid (Fertilome Tree & Shrub Systemic Insect Drench).  This must be applied AS SOON AS THE ASH TREE LEAFS OUT in the spring.  The objective of this application is to kill the EAB adults as they feed on Ash foliage prior to mating.  Incidentally, those EAB adults emerge from the D-shaped exit holes at the same time that Black Locust trees (Robinia) are in bloom.

We will send out an email when this occurs in northern Porter County and give you specific info on correct method of application.  If your Ash tree still looked healthy last summer and fall, it is probably not too late to protect it.  However, if your tree was already weakened and had dead branches, it amy already be too late.  We witnessed stumpage of an Ash tree that had been cut down last spring, and the EAB larvae, which started near the top of the tree, had progressed all the way down to the root flair (soil level) of that tree.  If you think your Ash trees are worth saving, DON"T ignore this warning. Even if this winter's cold temps killed a percentage of the EAB larvae, if you do nothing to protect them, your Ash trees will be nothing more than a memory.