Emerald Ash Borer, EAB, was recently discovered in Nemaha County in Southeast Nebraska.
Emerald Ash Borer is an invasive insect that was first found in Nebraska in the summer of 2016 when it was found in Omaha and Greenwood Nebraska. Now that it has been found locally, there are different actions that residents of Nemaha and the surrounding areas in Richardson County can take if they have an ash tree in their yard.
About EAB
Emerald Ash borer is a beetle, ½ inch long and metallic green in color. It has a bronze-purple color under the elytra, which are the hard wings on a beetle. The larvae may be found underneath the bark of ash trees. They are cream-colored and grow up to 1 ¼ inches long. The larvae have 10 segments to their body and some of the segments near the back of the body are shaped like a bell.
It is an invasive beetle species, native to Asia. It was first found in the United States in 2002, when it was discovered in Detroit, Michigan. It has been spreading throughout the United States since its introduction in Michigan. It can travel only a couple of miles per year on its own, but can be transported on plant material and wood products much quicker.
Damage from EAB
The damage from EAB does not come from the adults, it is the larvae that will kill ash trees. The larvae feed in the cambium layer of the tree, which is where water and nutrients are also moved through the tree. The larvae feeding will disrupt the flow of water and nutrients through the tree and initially top dieback will occur. They only feed on ash trees but can be in all ash trees including the commonly planted ‘Patmore’ and ‘Autumn Purple’. They will not affect mountain ash trees as they are not true ash trees.
The signs of EAB infestation include suckering at the base of an ash tree, decline in the tree from the top of the canopy downward through the tree, 1/8-inch D-shaped exit holes along the trunk and branches, increased woodpecker damage, S-shaped Serpentine galleries underneath the bark of the tree. One of the first signs is that the tips of the branches will be bare of leaves.
Management for EAB
EAB can be managed in a few different methods. The first thing is to make sure you have an ash tree. Ash trees have leaves that are arranged oppositely, meaning 2 leaves will come out from the same point on the stem. The leaves are compound with 5-11 leaflets per leaf. The seeds are paddle-shaped and found in large clusters and will stay on the tree until late fall or early winter.
From that, you can choose to remove and replace your tree or treat it. If you choose not to treat your tree but it is healthy and in a good location, there is no urgent need to remove it. However, if you remove it now, you can have more time to get a new tree started this fall. Also, when a tree dies from EAB it should be removed promptly to remove the hazards of falling branches. This information comes from the Nebraska Forest Service.
If you plan to treat it, you can do a soil drench with a product containing imidacloprid on trees less than 14 inches DBH (Diameter at Breast Height), these products should be used in May, so we would be too late to treat this summer but can put it on our calendar for next spring.
You can also have a certified arborist do a trunk injection or foliar spray for your tree. There is a product called Emamectin Benzoate which is an injection and it is effective for 2-3 years, so you don’t have to have it treated annually if you use this product. There are other products that can be injected that only last for one growing season and will need reapplied annually.
It is recommended to wait until it is found within 15 miles of your tree before treating it. At this time, the treatment zone would include the towns of Auburn, Peru, Brownville, Nemaha, Stella, Shubert, Falls City, Dawson, Rulo, Verdon, and Salem.
For more information on Emerald Ash Borer, you can visit the website focused on EAB information from the Nebraska Forest Service found at: https://nfs.unl.edu/nebraska-emerald-ash-borer
If you have any further questions please contact Nicole Stoner at (402)223-1384, nstoner2@unl.edu, visit the Gage County Extension website at www.gage.unl.edu, or like my facebook page at http://www.facebook.com/NicoleStonerHorticulture and follow me on twitter @Nikki_Stoner
Nicole Stoner
Extension Educator
Gage County
July 2023