Emerald Ash Borer—Where Is It In Nebraska and When Should Tree Owners Treat For It?
By Kathleen Cue
Nebraska Extension Horticulture Educator

The much-dreaded emerald ash borer (EAB) was identified in Douglas County in 2016.  Since that time, EAB has been found in several other locations that holds implications for counties in the eastern part of Nebraska.

Infestations of this insect are known to kill ash trees in a relatively short time period—from 3 to 5 years in most cases.  Once an ash tree is dead, the tree quickly becomes brittle and is a threat to nearby homes, vehicles, and yes, people.

Treatment for EAB is recommended for areas that lie within a 15 mile radius of confirmed infestations. (The treatment areas are depicted as the yellow circles.) If you have an ash tree within the treatment area, you may want to consider having the tree treated or treating it yourself.

First and foremost, make sure you have an ash tree.  A mountainash (with the botanical name Sorbus) is not a true ash tree at all and should not be treated for EAB. Green, white (sometimes called purple ash), blue and black ash (all with the botanical name Fraxinus) are true ash and are candidates for infestation by EAB. If you’re unsure if your tree is an ash, cut a 12-inch long branch sample to take to your local Extension Office for identification.

Second, make sure your tree is a good candidate for treatment against a potential infestation.  The healthier the tree, the more evenly the insecticide can be distributed throughout its vascular system, which provides better protection.  Trees with double leaders, trunk wounds and/or are planted too deep are not good candidates for treatment. If you’d like assistance to determine if your ash tree is healthy enough to be treated, check out the Emerald Ash Borer decision guide link below.

Third, determine the diameter (distance from one side of the trunk to the other) of the tree at 4-½ feet from the ground.  If the diameter is less than 20 inches, tree owners can treat the tree themselves with products readily available from garden centers and hardware stores. If the tree has a diameter equal to or greater than 20 inches, contact a tree service to find out more about injectable options.

Information about the emerald ash borer and the decision guide may be found at these links:

Emerald Ash Borer Map for State of Nebraska

A Tree-Owner's Guide to Emerald Ash Borer  -  By Dr. Jonathan L. Larson, Nebraska Extension Entomologist