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Close up view of emerald ash borer

Land-grant Universities Key in Managing Devastating Emerald Ash Borer

Nifa Authors
Lori Tyler Gula, Senior Public Affairs Specialist

Emerald ash borer (EAB) is an invasive insect that threatens to destroy North American ash trees following its accidental introduction from Asia in the 1990s. Since then, efforts have been underway to identify the most effective means of protecting ash trees from attack.  


In recent years, EAB has become a significant threat to urban and community forests throughout the nation as it kills both stressed and healthy ash trees that not only beautify neighborhoods but provide shade to cool streets and homes. Loss of these trees has a staggering economic impact on communities that must  spend thousands of dollars to manage or remove infested trees and replace with other species.  

On Arbor Day, learn how scientists and Extension staff at Land-grant Universities are helping their communities and states manage this invasive pest with funding from USDA’s National Institute of Food and Agriculture.

Managing the Emerald Ash Borer in Urban and Natural Forests 

The most successful and cost-effective approach for protecting individual ash trees from EAB is with an injection of the insecticide emamectin benzoate into the trunk. A single injection provides protection for multiple years. Recent research suggests ash tree mortality can be slowed by treating just 40% of trees in a community with insecticides and targeting the period before EAB females lay their first egg.  

Called Slowed Ash Mortality (SLAM), this program is based on applying insecticides early in the invasion to kill most beetles before eggs are laid. Most municipalities, however, are hesitant to employ this approach without validation of varying stages of EAB invasion. 

To address this reluctance, researchers at Purdue University tested the capacity of the SLAM program to protect ash trees at urban forest sites at the cusp of an EAB invasion. They found that an area-wide strategy to destroy EAB can substantially reduce the costs of managing ash trees in cities and retain the benefits provided by mature urban trees, with minimal impacts on other organisms or the environment. 

Some Green Ash Trees Show Some Resistance to the Emerald Ash Borer 

Since first appearing in the United States, EAB has killed tens of millions of ash trees. However, a small percentage of trees survive and may hold clues about how to rescue the species. As a result, researchers at Pennsylvania State University conducted a study to determine why some green ash trees survived an EAB outbreak. 

A team of plant geneticists compared gene expression data for resistant versus susceptible green ash trees exposed to attack by the beetles. By comparing RNA-sequence data from stems attacked by EAB to multiple tree tissues under other stresses, the researchers identified the genetic differences tied to EAB resistance. 

The team now is evaluating green ash seedlings from an EAB-resistant parent tree to map the location of genes for resistance among the offspring that survive natural EAB attack. They also are sequencing the genome of the resistant parent tree to identify specific resistance genes for selection and breeding. Geneticists believe they may be able to selectively breed trees to strengthen them and perhaps move the resistance response earlier to ward off the beetles' onslaught. 

Recruiting Community Volunteers for Emerald Ash Borer Education 

Increasing public awareness about EAB encourages peoples to take action to help the places where they live, work and play to better manage this pest through information sharing as well as monitoring and reporting of trees suspected to be infested. As a result, the University of Vermont Extension’s Vermont Urban & Community Forestry Program (VT UCF) partnered with the Vermont Department of Forests, Parks and Recreation; the Vermont Agency of Agriculture, Food and Markets; and the Vermont Land Trust on EAB Awareness Week in May 2021.  

VT UCF educated participants and gave away EAB Awareness Week Toolkits. Volunteers in the Forest Pest First Detector program and members of state conservation commissions created publicity and outreach and education events in their communities. As a result, residents are learning about EAB and management options from other residents of their communities.  

For example, a Forest Pest First Detector, who also is a town tree warden and forest owner, used materials and support from the VT UCF program to develop an invasive pest awareness booth at his town's Memorial Day Celebration, the largest and most well-attended town-wide event. As a result, approximately 60 town residents received information about the threat of this invasive pest and management options for different types of property (yard, forest, and municipal) through one-on-one conversations and educational literature.  



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Bioenergy, natural resources, and environment
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