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Ash pest confirmed in Kentucky

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By Jeneen Wiche

For over a decade entomologists to the north have been monitoring a pest that has devastated ash tree populations. Michigan was the first see the drama unfold, and all told since active monitoring of the emerald ash borer, an estimated 40 million trees have been killed. 

It was inevitable that the pest would move south despite active efforts to contain the pest through quarantines, voluntary and mandatory felling of ash trees and a campaign to prevent the movement of firewood out of infected areas.

The emerald ash borer was confirmed in several Southern Indiana counties last year; this May, Shelby and Jessamine counties in Kentucky make the list. 

You may have noticed purple things hanging from trees here and there, these purple panel traps are a part of the effort to monitor the insects’ spread. 

If the emerald ash borer is in the area the panels attract them with phoebe and manuka oils and the glue on the panels traps them. They are checked periodically so forestry officials and entomologists can devise a quarantine plan, if and when necessary.

So, the emerald ash borer is close. 

It is often elusive because in the adult stage the small metallic-green insect usually hangs high in the canopy of an ash tree where it munches foliage. This is not necessarily the problem because it is the larval stage of the insect that kills the tree. 

The adult lays her eggs on the trunk just beneath the bark and as the larvae develop, they feed and disrupt the vascular system of the tree thus preventing the movement of food or water to the upper portions of the tree.  They kill trees pretty fast, too, usually in a matter of a couple of years. 

Because the emerald ash borer is native to Asia (they believe it was first introduced via wooden shipping crates made from an Asian species of ash) and has no known enemy in North America, it has managed to move fast and kill many trees along the way.  This year the good news is that entomologists have determined that there is an effective preventative measure we can take if we want to keep healthy trees healthy. 

I am not one to pick up chemicals at the local garden center, but this time around I did not hesitate. I have followed the advice of Purdue University Entomologist Jodi Ellis, who has been monitoring the pest in Indiana for several years now; she warned it was here and she was right. 

She explains that thus far the proven treatment involves using a soil drench of 1.47 percent of imidacloprid.  Imidacloprid is a systemic insecticide that if used as a soil drench is taken up by the roots of the tree and therefore into its vascular system. If there are emerald ash borer larvae feeding on that same system then they are killed. 

Here are the rules of the game though:  You can treat the tree yourself if the circumference of the tree is 45 inches or less. Measure the circumference at breast height. Shop for a product that has 1.47 percent imidacloprid. Double check the active ingredients listing because not all products have the higher percentage.

Most of these products are labeled as a systemic “Tree and Shrub Soil Drench”.  Bayer, Bonide, Gordon’s and Fertilome are some product labels to look for. Use the product according to label instructions (you have to measure your tree to determine the rate of application); only us it once a year and make the application in the spring. 

Jodi Ellis explains that April is ideal although we can still get coverage now. From now on shoot for April. 

A tree care professional will need to be employed if the trunk circumference is larger then 45 inches; the professional treatment lasts for two years. And, yes, most of us realize that not all trees can or will be personally or professionally treated so weigh the value of your ash and realize that preventative treatment will help keep healthy trees safe and help stop the spread of the emerald ash borer.