Minnesotans continue to lead the fight against emerald ash borer (EAB). The invasive insect that tunnels into ash trees, causing mortality, was first discovered in Minnesota in 2009. Since then, the Minnesota Department of Agriculture (MDA), with state, federal, and local partners, alongside thousands of Minnesotans, has worked to manage this invasive pest. Management efforts in Minnesota are vital, as there are more ash trees here than in any other state. The loss of ash trees carries especially serious environmental and economic impacts in Minnesota.
The goal of EAB management is to slow the spread of infestations. Slowing the spread helps communities avoid the sudden loss of ash trees and gives local governments, landowners, and forest managers more time to plan and respond. The MDA leads a coordinated effort that includes surveying for new infestations, releasing biological control insects that target EAB, and educating the public on ways to avoid moving the pest. Together, these steps are essential to preserving Minnesota’s urban and rural forests.
Survey
Early detection is one of the strongest tools to slow the spread of EAB. Surveys are conducted along the leading edge of infestations and on high-risk travel corridors. The Walz-Flanagan Administration places a significant emphasis on minimizing the impact of EAB, allocating essential funds to early detection. With extra grant funds from the Minnesota Department of Natural Resources (DNR) the MDA has been able to conduct over 200 additional early detection surveys in cities across the state leading to numerous new community detections. MDA staff also engage communities in management workshops to boost the number of people looking for EAB. Early detection of EAB in new areas allows communities time to prepare by removing trees, planning for replacement, and slowing the spread into nearby areas.
EAB biological control
The goal of biological control is to introduce natural enemies of EAB to reduce pest populations. Three species of parasitoid wasps are released in Minnesota to attack EAB. Since 2010, 700,000 wasps have been released at 56 EAB-infested sites across Minnesota. These wasps do not sting people or damage trees; they simply attack EAB. Research on the impact to EAB populations is ongoing, but early results show promise. The long-term goal is for these wasps to establish self-sustaining populations that help keep EAB numbers lower over time, especially in forests where removing thousands of trees is not feasible.
Public education
Humans are actually the number one way that invasive species are spread. This is often due to accidentally transporting the species on other objects, such as firewood. The MDA has made a significant effort to change public behavior to limit the spread of EAB. There are two main ways the public can help — by not moving firewood and by reporting suspicious insects or signs of EAB infestations to Report a Pest.
Looking ahead
For many years, combined management efforts and environmental conditions have led to EAB spreading slower here than expected. That’s no longer the case. Sixty Minnesota counties are now considered EAB-infested, mostly in the central and southern parts of the state. However, in recent years infestations have started to creep north. The increased rate of spread and northern movement is unfortunate but not a surprise given rising winter low temperatures.
Limited research is available on how EAB populations will be affected by cold winters as the pest continues to spread into northern Minnesota. It is possible that they will spread slower due to colder temperatures. However, even at a slower rate of spread, EAB poses significant challenges in northern Minnesota, where black ash trees blanket much of the forest. Forest managers have an uphill battle to find ways to use all the inevitable ash waste as well as make plans for replacement species.
Although EAB has proven to be a pest of significant concern and poses many challenges in Minnesota, the experts at the MDA, the University of Minnesota, the DNR, the U.S. Department of Agriculture, other partner agencies and organizations, and diligent members of the public have done a great deal of successful work to slow its spread. Through continued hard work and scientific research, management efforts can improve and mitigate some of the economic and environmental harm to Minnesota forests.
Listen to the Minnesota Department of Agriculture’s latest episode of Smarty Plants for an in-depth discussion of EAB in Minnesota over the last 17 years.
