KC Gardens

Emerald ash borer -- Update

Ash tree

Tip of the Week

Emerald ash borer (EAB), the dreaded exotic wood boring beetle, was first found in the eastern United States in 2002. Since its first detection millions of ash trees have been killed. In the summer of 2012 this insect was discovered in the Kansas City area, having being found both on the Missouri side, in Parkville, and on the Kansas side, at Wyandotte County Lake Park. The dreaded fear has finally come true.

The summer of 2013 brought with it the discovery of EAB in both Johnson County, Kansas, and Jackson County, Missouri. As a result of these findings, people with ash trees are concerned about the impending loss of ash species in the Kansas City area. People are asking such questions as, “Will my ash tree die?”, “Can I treat my tree to prevent the problem?”, or simply, “Now what?”

These are all very good questions. In order to help determine the answers to these questions I can update you on what is happening on the Kansas side to monitor the insects’ spread, and get a better handle on the problem. The following agencies are working together to determine the presences of EAB in Kansas: Kansas Department of Agriculture, lead agency; Kansas Forest Service; K-State Research and Extension; and our partners at the USDA.

This past spring seven trees were girdled to create what is referred to as a trap tree. Two trees were girdled in Leavenworth County, three in Wyandotte County and two in Johnson County. The girdling process involved removing a section of the bark to place the trees under stress. The theory is that adult EAB beetles and other wood boring insects are initially attracted to stressed trees. But, it is important to point out that EAB will attack and kill both healthy and stressed trees.

Areas of the trap trees were also covered with a sticky material to catch any adult beetles that would fly to the trees and lay their eggs. When these eggs hatch it is the larvae boring into the tree that creates the problems which lead to the death of the tree. The trap trees were then monitored over the adult EAB’s summer flight period. Finally the trees were cut down and the bark stripped to look for the presence of any EAB larvae. Over the summer months two of the trap trees caught adults of the EAB insect. These were both on trees at Wyandotte County Lake. No EAB adults were found on trees in Leavenworth and Johnson County. Keep in mind that the only insect found in Johnson County was on a trap set in the vicinity of I-435 and Holiday Drive.

Last week a group of eager researchers cut down the seven trap trees and stripped the wood to search for EAB larvae. The results were a mix of good and bad news. Just like the hunt for adults, none of the trap trees in Leavenworth and Johnson County detected EAB larvae. But in Wyandotte County, two of the three trap trees were infected with EAB larvae. I was involved in the removal of the Johnson County trees, and the find at one of the Wyandotte County trees.

Finding these small larvae was not easy. EAB initially attack in the upper canopy of the tree. They were found in the upper half or third of the infested tree, and only after stripping the bark to a depth of around 1/4 inch. So this means most of us will never know our tree is infected until it is close to death. Simply put, we will not see the telltale “D” shaped exit holes or larvae unless we cut down the tree and strip the bark.

So what does this tell us? Well, it tells us that Kansas and Missouri will fair no better than any of the other 20 some states that have active EAB populations. It means that over time, the next 10 years or more, we will lose the vast majority of our ash trees in both urban and native settings. The spread will start out slowly. But then, about five years after the detection, the problem will explode, with thousands, and hundreds of thousands of declining and dead ash trees lining streets.

What can be done now is an excellent question. The best approach at this time is not to panic. We have time to plan and make wise decisions in regards to our ash trees. Each ash tree will need to be evaluated for its health. Trees with poor structure, in declining condition, or planted in the wrong location should not be treated but removed and replaced. Only trees in excellent health and condition should be considered for treatment.

So there you have it — the latest breaking news on emerald ash borer on the Kansas side. Those of us with ash tree, and yes that includes me, will need to stay tuned. We will need to have discussions about what to do with our trees and whether we treat, remove, let it die, and most importantly, replant for the next generations. As for me, I am still undecided as to which course of action I will take.

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