Forest Insect and Disease Newsletter

Emerald ash borer update

map: EAB status map of the Metro Area from MDA

Click to enlarge

Emerald ash borer (EAB) was first detected in Minnesota in May 2009 by a private arborist in St. Paul (Ramsey County). In February 2010, a separate infestation was discovered in a nearby park in Minneapolis (Hennepin County), and in April of that year, EAB was confirmed in Houston County on the Upper Mississippi Fish and Wildlife Refuge. The Minnesota Department of Agriculture (MDA) enacted an emergency quarantine on Hennepin, Ramsey and Houston Counties in May 2009, followed by a formal quarantine in August. The United States Department of Agriculture Animal and Plant Health Inspection Service, Plant Protection and Quarantine (APHIS PPQ) imposed a parallel federal quarantine.

map: EAB status map of Houston and Winona Counties from MDA

Click to enlarge

In August 2011, three EAB traps were found positive along Highway 61 in Houston and Winona Counties. As a result, the quarantine was extended to Winona County. A large EAB infestation was discovered a month later at the I90/CR12 interchange in Winona County, and infested trees were subsequently found in Great River Bluff State Park less than two miles away. Additional small infestations were discovered in 2012, including Shoreview (Ramsey County), St. Paul, Minneapolis, Houston County, and at the Fort Snelling Golf Course in Hennepin County near the Minneapolis-St. Paul International Airport. And now, in January 2013, three more infestations have been discovered: in St. Paul's Como Park area, on Pig's Eye Lake Road, and in Lakewood Cemetery near Lake Calhoun in Minneapolis.

In most cases, state or city officials continue to remove and destroy infested trees during the winter months. However, this is no longer possible at all locations due to site access issues. Some trees have been taken to the University of Minnesota quarantine facility to support state-funded research to explore the spread rates and cold tolerance of EAB and three biological control agents. These biological control agents, including one egg parasitoid and two larval parasitoid species, have been released by MDA near most known infestations. 

MDA is the lead agency responsible for the detection and management of regulated pests, and the DNR serves a support role in planning and implementation efforts involving pests impacting Minnesota's natural resources. In 2011, an agreement was made with MDA that DNR Forestry would be available to take a lead role for managing EAB infestations found outside the seven-county metro area in rural Minnesota when requested. In 2012, the DNR assembled an incident command team led by members of county and municipal governments in addition to DNR Forestry and MDA to lead the long-term response to EAB in Winona County.