If you have ash trees on your property, especially ash trees you value and want to keep, you need to be aware of emerald ash borer. Since it was first detected in the US in 2002, this non-native pest has killed hundreds of millions of ash trees. This little green beetle has already killed so many ash trees that it threatens the future of wooden baseball bats, and it continues to spread. Mississippi and Florida are the only states east of the Mississippi River that do not yet have emerald ash bores, but it is just a matter of time. EAB is established within a couple of counties/parishes of the Mississippi River in Arkansas and Louisiana, but because this pest is easily transported in ash firewood, it could appear anywhere in the state any time now.
How serious is this pest? Experience in other states has shown that once EAB arrives in an area, trees that are not properly protected from EAB will be killed by EAB. Mortality rate of untreated trees is around 99%. Unlike most other wood-boring insects that kill trees by inoculating them with disease organisms, EAB works alone. The larvae feed in the cambium layer, girdling the tree and preventing translocation of water and nutrients. Infestations usually begin in the upper canopy of the tree and work their way down. Once a tree sustains 25 to 50% crown die-back, it is usually too late to save the tree.
Control: Effective treatments for EAB include systemic insecticides such as dinotefuran or imidacloprid, applied either as a soil drench, trunk injection or basal trunk spray, as well as emmamectin benzoate applied as a trunk injection. To be effective treatments must be applied before EAB becomes established. Begin preventively treating trees you want to retain once EAB is reported within 15 to 30 miles of your location. Depending on treatment choice, treatments must be repeated every one or two years.
How do you know when EAB is getting closer? Unfortunately, the federal trapping program that tracked the spread of EAB was terminated after 2018. This places a greater burden on Mississippi citizens to be aware of EAB, to learn to recognize signs of early infestation, and to report suspected infestations to their local county extension office. Periodically check with your local county extension office to learn if EAB has been reported in the state and how close they are to your trees and stay alert for news articles about EAB occurrence in Mississippi.
See extension publication 3212, Protect Landscape Ash Trees from Emerald Ash Borers, for more information on how to recognize signs of EAB infestation, recommended treatments and how to apply them.
Photo by Debbie Miller, USDA Forest Serv., Bugwood.org
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service. The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.
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