What is it?
Emerald ash borer (EAB) is an invasive beetle that was first discovered in the United States near Detroit, Michigan in the summer of 2002; it is guessed to have arrived in the US from cargo ships and airplanes originating from its native range in Asia (Matsoukis). It was first discovered in Virginia in 2003, they were able to eradicate it but unfortunately it came back to stay in 2008. It only affects ash trees, but it will kill all types of ash trees besides the mountain ash. The adult beetle has a long shiny green body and is significantly smaller than a penny.
How are the trees affected?
The first symptoms present on a tree infested with EAB are D-shaped holes in the bark, the bark will also start peeling. A sign that your tree might be infested is if you notice woodpecker holes along the bark, this indicates that there are insects under the bark. The adult beetle only causes minimal damage to the trees, it is actually the larva that kills the ash trees. The larvae feed on the inner bark, this damages the trees ability to transport water and nutrients, the first sign of this will be a decrease in foliage but it will eventually lead to the trees death (Matsoukis). If you removed the outer layer of the bark you would see trails from where the larvae have fed. A large tree can be killed within 3-4 years and a small tree can live 1-2 years with an infestation. As of October 2018, this pest is found in 35 states and has killed hundreds of millions of ash trees in North America; it has caused regulatory agencies to enforce quarantines and fines and has cost people hundreds of millions of dollars in removals (Matsoukis).
How can you treat it?
There are currently two options in treating emerald ash borer, chemical control and biological control. The most effective chemical control found has emamectin benzoate in it, studies show trees treated with trunk injections with this chemical show improvements in chlorophyll concentration and overall plant health (Hanavan). Injections directly into the tree are more effective than spraying because the insecticide gets into the tree's vascular system much quicker, and it also does not kill any beneficial insects or affect the soil directly next to the tree.
The biological control option involves releasing emerald ash borers natural predators into an area with ash trees, these “enemies” will eat the invasive insects and help decrease the population. Currently the USDA has an emerald ash borer biological control program to release these parasitoid species, there have been four species approved for release in the United States and most states are now using these predator insects as a control option (Matsoukis). This biological control option is typically difficult for individual home owners to implement because these parasitoids are not typically available to buy unless you are partnered with someone conducting research, for this reason chemical control is typically the best option for the average person.
Hanavan, Ryan P., and Molly Heuss. “Physiological Response of Ash Trees, Fraxinus Spp., Infested with Emerald Ash Borer, Agrilus Planipennis Fairmaire (Coleoptera: Buprestidae), to Emamectin Benzoate (Tree-Äge) Stem Injections.” Arboriculture & Urban Forestry, vol. 45, no. 4, July 2019, pp. 132–138. EBSCOhost, search.ebscohost.com.ezproxy.lib.vt.edu/login.aspx?direct=true&db=a9h&AN=137301839&scope=site.
Matsoukis, Christian. “Emerald Ash Borer Information Network.” Emerald Ash Borer, www.emeraldashborer.info/.
About the Author:
Plant Health Care Technician & Social Media Intern
Lexi has joined the team this summer to assist with plant health care and run our social media accounts. She is majoring in Environmental Resource Management and is double minoring in Ecological Cities and Forestry at Virginia Tech.