Horticulture News: Emerald Ash Borer here to stay

By Kim Cowherd Published:

The Emerald Ash Borer is officially in Kentucky and our own Franklin County to stay and its presence throughout the state will continue to grow.

A sound plan for living with it has been developed based upon research findings and experiences from older infestations in other states. The challenge is to do everything we can to make the plan work and learn to manage the EAB.

EAB adults are 3/8 to ¾ inch long and very narrow (about 1/5” wide). The head is blunt, the body tapers noticeably at the end of the abdomen. The wing covers are emerald green; the top of the abdomen, visible when the wings are spread, is metallic purple-red.

Adult emerald ash borers are active in mid-spring to early summer. Emergence has already begun in central Kentucky and, like everything else this year, about three weeks early because of warm temperatures. The flying adult stage should begin to taper off after about six weeks or so. Individual adults live for about three weeks but emergence occurs over several weeks so the activity period in Kentucky may extend from early May to late June or beyond.

What trees does the EAB attack?

All species of ash (Fraxinus) in landscapes, forests, and woodlots in eastern North America are susceptible. Females may prefer to lay eggs on stressed trees but healthy ones also can be infested. Host tree size does not appear to be a constraint either, larval galleries have been found in trees or branches as small as 1-inch in diameter.

What does the EAB do to ash trees?

As they feed under the bark, EAB larvae destroy the tree’s water and nutrient conducting tissue. This reduces water and nutrient flow to the canopy and causes thinning above infested portions of the trunk and major branches. Dieback in heavily infested trees usually starts at the top with one-third to one-half of the branches dying in one year; most of the canopy will die within two years of the first appearance of symptoms.

This is the stage of infestation we find ourselves in Franklin County.  Discussions with several ISA Certified Arborists and professional horticulturists in the county found us all noticing thinning canopies and dead limbs in many of our local ash trees. These trees are in subdivisions, woods, parks and lining streets all across our county. 

The next thing we also noted, the ashes that have been treated according to research-based, recommended practices, are appearing to be much healthier, with little to no loss of foliage. The age of the tree or location in the county didn’t matter. 

How do infestations spread?

Normal flight spread of the EAB is between one-half to two miles a year so natural spread tends to be relatively slow. Unfortunately, movement of infested ash wood can result in jumps of hundreds of miles.

Firewood has been a major means of transporting EAB, especially by hunters and campers. Slowing the spread can buy time to develop and implement management plans based on ash components of wooded areas and to take advantage of strategies that might be developed through current research.

What can homeowners and property owners do for their ash trees?

You can contact a certified, licensed arborist who is knowledgeable and trained in specific insecticide treatments. Or contact the Extension Office. While it is no longer necessary to call in experts to positively identify the EAB presence, since we know it is here, you can obtain information that can help you make decisions in managing your ash trees. 

Some ash trees that haven’t yet started to be treated may not yet be infected. If the owner decides to keep the tree, treatments need to be started soon in order to have the best chance of survival. If the tree has some characteristic EAB signs, but is mostly fully leaved out, those should also begin treatments to try to stop any further potential damage by EAB.

However, if your ash tree appears dead except for possible small sprouts coming off the trunk or from the base of the tree, or no leaves are on the tree at all, or most of the bark is falling off, then there is very little that can be done to save the tree. 

Homeowners can purchase and apply products containing the active ingredient Imidacloprid.  This chemical is mixed with water and poured at the base of the tree’s trunk.  Be sure that you read and follow all directions with chemical applications and be sure the product you purchase states it can be used on Ash trees for EAB. One such product is Bayer AdvancedTM Tree & Shrub Insect Control.  This insecticide is best when used in Mid-fall or mid- to late spring. 

Do be aware that there are many other problems that can affect ash trees, not just the Emerald Ash Borer. Also know that EAB only attacks ash trees.  

So be aware and be informed. For more information on EAB control, log on to http://pest.ca.uky.edu/EXT/EAB/EABcontrol.pdf or contact the Extension office for a printed copy.

For additional information on EAB check out emeraldashborer.info/homeownerinfo.cfm, pest.ca.uky.edu/EXT/EAB/welcome.html, or contact the Extension Office to obtain printed copies of Emerald Ash Borer information.  

Contact the Franklin County Extension Office if you have questions at 695-9035 or would like printed information or email Kim.Cowherd@uky.edu.

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