Michigan's Revised Hemlock Woolly Adelgid Quarantine


Photo: Steven Katovich, Bugwood.org

LANSING – The Michigan Department of Agriculture and Rural Development (MDARD) revised the State of Michigan’s interior hemlock woolly adelgid quarantine. The new quarantine is effective as of August 1, 2023. 

The updated quarantine now includes Benzie and Manistee counties as well as a portion of Washtenaw County in and around the Nichols Arboretum after the pest was identified in these areas. The previous interior hemlock woolly adelgid quarantine regulated movement of hemlock in Allegan, Mason, Muskegon, Oceana, and Ottawa counties.

The quarantine regulates the movement of hemlock and tiger-tail spruce trees, forest products and nursery stock, with some exceptions, from the quarantine areas to other locations within the state. 

“Our goal is to protect the 170 million hemlock trees that live in Michigan’s forests,” said Mike Philip, Director of MDARD’s Pesticide and Plant Pest Management Division. “According to the U.S. Department of Agriculture Forest Service, hemlock trees have a strong impact on streamside habitat conditions and stream health. Loss of hemlock could result in a rise in water temperatures in streams and an increase in soil erosion, something Michiganders certainly don’t need to further experience." 

Trees infested with hemlock woolly adelgid should be reported by one of the following means:

·         Email MDARD at MDA-Info@Michigan.gov.

·         Call the MDARD Customer Service Center at 800-292-3939.

·         Use the Midwest Invasive Species Information Network online reporting tool.

·         Download the MISIN smartphone app and report from your phone.

“If left unchecked, hemlock woolly adelgid could spread throughout Michigan’s hemlock trees, causing significant losses and affecting the timber and lumber industries, nursery and landscaping industries, the Christmas tree industry, and the tourist industry,” added Philip. “Hopefully, by expanding quarantine area, we can keep the pest from moving to new areas in the state and slow the spread within the currently infested areas.” 

Be prepared to report the location of infested trees and, whenever possible, take one or two pictures of infested branches to help confirm identification. To avoid spreading hemlock woolly adelgid, do not collect sample branches or twigs.

The MISIN smartphone app will take a GPS location point if a report is made at the site; it also will allow you to upload photos with a report.

The updated hemlock woolly adelgid interior quarantine is available online at www.Michigan.gov/HWA. Suspected quarantine violations can be reported by emailing MDARD-NurseryCE@michigan.gov. For more information about invasive species in Michigan, visit Michigan.gov/Invasives.