Husker Hort

A Nebraska View of Horticulture

Emerald Ash Borer in Nebraska

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eabWe can stop with the ‘if and whens,’ Emerald Ash Borer has been confirmed in the state of Nebraska.  Find out what that means for your beloved ash trees and what you should be doing now and what you can hold off on for a little while longer.

The Nebraska Department of Agriculture (NDA) confirmed the first finding in the state of Emerald Ash Borer (EAB), an invasive beetle that attacks and kills all species of ash trees, in a tree located in Pulaski Park in Omaha last week.  Nebraska will be the 27th state to confirm the presence of the pest since 2002.

EAB is a small, metallic-green beetle that is about ½ inch long. The larvae of this wood-boring insect tunnel under the bark of ash trees, disrupting the flow of water and nutrients, ultimately causing the tree to die. EAB infested ash trees will exhibit thinning or dying branches in the top of the tree, S-shaped larval galleries under bark, D-shaped exit holes and suckers (along the trunk and main branches).

There are several different types of borers that attack ash trees, so correct identification is key.  Just because you have borer holes in ash trees, doesn’t necessarily mean you have EAB.  There are several different native borers that are normally found on ash trees.  The ash/lilac borer, banded ash clearwing and carpenterworm can attack healthy ash trees.  The redheaded ash borer, banded ash borer, flatheaded apple tree borer and eastern ash bark beetle attack stressed or dying ash trees.  Knowing exactly which insect is in your tree will let you know if you should start looking for a replacement or if you need to treat.

Know your trees.  If you are not sure of what kind of tree you have, get it properly identified first before taking any further steps.  Ash trees have an opposite leaf pattern, or the buds are across from one another on the stem.  It also has a compound leaf that is made up of several smaller leaflets.  If you are lucky enough to get the seeded variety, the seeds look like paddle-shaped helicopters and are held in clusters on the tree.  Proper identification is key to knowing if you should be concerned about EAB or not.  Ash trees, those in the Fraxinus genus, can include the green, white, Patmore, Marshall’s Seedless, and Autumn Purple Ash.  Mountain Ash is not affected because it isn’t a true ash, it’s in the Sorbus genera.

If you do have an ash tree, know when you need to take action.  If your tree has EAB-like symptoms, like canopy thinning, branch dieback, sprouting growth from the base of the tree, or D-shaped exit holes it should be examined by a professional.  Leave your ash trees in as long as they are healthy, in good condition, and in a good location.  If your tree is dying or diseased, it may be best to hire a certified arborist to look at your trees and determine the cause of the trees’ decline.

No treatment is recommended until EAB has been detected within 15 miles of your location.  Once EAB has been confirmed within the 15 mile radius of your location, then you can begin the proper treatment applications.  A soil drench is one option for homeowners.  Keep in mind that the drench will need to be applied to the tree yearly throughout the lifespan of that tree.  Tree care professionals are able to use additional products like trunk injections as well as trunk and foliar sprays.  Contact a certified arborist for these treatments.

Diversity, diversity, diversity.  Ash has been a popular landscape and conservation tree for a long time.  Due to its fast growing nature and overall appearance, it’s easy to see why it was continually planted.  Diversity in the landscape is important to the overall health of the community forest.  Aim to have diversity, try not to have any one species make up more than 10% of the landscape.  This is helpful when we have infections and infestations occur so that a majority of the landscape isn’t affected by the one outbreak.  Now is an excellent time to start thinking about replacement trees for ash.

More information about the emerald ash borer, finding an arborist, and recommendations can be found at

Elizabeth Killinger is the Horticulture Extension Educator with Nebraska Extension in Hall County. For more information contact Elizabeth at, her blog at, or HuskerHort on Facebook and Twitter.



Author: Elizabeth Exstrom

A Nebraska Extension Educator out of Hall County with a focus in horticulture and sustainable landscapes.

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