April O'Neil / news@WHMI.com

The Michigan Department of Agriculture and Rural Development (MDARD) revised the state of Michigan’s interior hemlock woolly adelgid quarantine, including areas of Washtenaw County.

The new quarantine is effective on 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 those 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."

Phillips said 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.

“Hopefully, by expanding the quarantine area, we can keep the pest from moving to new areas in the state and slow the spread within the currently infested areas.”

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