Are you wondering if the emerald ash borer (EAB) is here, in your yard, perhaps in your community in western Nebraska? Have neighbors or other persons told you it is already here?
EAB was found in an Omaha park and in Cass County in June 2016. But it has not been confirmed nor identified in western Nebraska by the Nebraska Forest Service or the Nebraska Department of Agriculture. Any reports that EAB is in western Nebraska are not correct, according to Rachel Allison, western forest health specialist with the Nebraska Forest Service.
Allison recommends that anybody with an insect that is suspected to be the EAB should have the insect identified and passed along to one of the agencies above. She said it is very likely that it is another insect that has already been here, like the lilac (ash) borer or other tree borer, which has been associated with ash trees for many years.
“These insects are prevalent in trees that are stressed by drought, early cold and later spring freezes, overwatered lawns, as well as lawn herbicides used to kill dandelions and other weeds. Most importantly, these insects that are here now and are the real culprit in western Nebraska need to be treated differently than what would be used for the EAB.”
If ash trees are treated before EAB gets to a community, it is possible that EAB may not reach the western communities for several years, or if it does arrive in a year or two, it will be seen first in other communities as it advances or moves across the state.
Treatments for EAB are usually applied by one of two methods, injection or soil drench. When a tree is injected, the tree will be damaged some each time it is injected over the years, more with each injection. Allison said it is best to wait until EAB is known to be close by before beginning treatments so that the damage to the tree can be minimized.
Drilling a hole and injecting a liquid under the bark of a tree creates an area of dead tissue, and several applications with multiple injection sites makes it difficult for the tree to move the water and nutrients it needs to survive. The tree reacts to these injected sites as wounds and develops defensive tissue, restricting and directing the normal flow of healthy tissue away from that area. Yearly or even biennial injections eventually end up blocking the flow of very important water and nutrients from the ground to support and maintain the health of the tree.
The other treatment method, a soil drench, harms not only the tree but also other beneficial insects in the soil around the ash tree, according to Allison. Those insects help to create living soil, very important to nutrient breakdown and development of organic matter critical for a healthy tree and plant survival.
While it may seem simple to apply the pesticide and directly target the problem insects, research shows that this product, imidacloprid, leads to the decline of many insect, butterfly and bird species.
There are also several limitations to consider when applying the soil drench. The pesticide cannot be used in all locations, particularly wet, sandy or compacted sites typical of some yards. Also, a soil drench has restrictions for the amount that can be placed within a city block.
What should you do? Allison suggests that first, don’t apply a pesticide when you’re not sure of the reason for the treatment, or not sure if you have EAB. Second, learn why the treatment for EAB is both damaging to the tree and harmful to the environment. Third, owners of ash trees who are concerned about its health and the possibility of EAB being present, should visit http://eabne.info/ for information, or email questions to trees@unl.edu.