June 8, 2017

June 6, 2017              To: Stakeholders and Industries Associated with Hemlock

The Michigan Department of  Agriculture and Rural Development (MDARD) is implementing an interior state quarantine to protect Michigan’s native and cultivated hemlock populations from hemlock woolly adelgid (HWA). HWA has not been found in Michigan until recently where it has been detected at multiple sites in four counties in western Michigan. Recent surveys show HWA to be infesting hemlock in native stands and landscape settings. The infestations are attributed to shipments of hemlock nursery stock from infested areas in the United States prior to the implementation of Michigan’s Exterior HWA Quarantine. If left unchecked, HWA will likely spread throughout the estimated 170 million hemlock trees in Michigan. HWA causes significant losses in hemlock and therefore, could adversely affect a wide range of industries including the timber and lumber industries, nursery and landscaping industries, the Christmas tree and greens industry and also the tourist industry. Furthermore, hemlock is a keystone species in forested and associated riparian ecosystems.

The Michigan HWA Interior Quarantine regulates the movement of hemlock (Tsuga spp.) and tiger-tail spruce (Picea torano) nursery stock and any part of those species’ trees that presents risk of spreading HWA. Since HWA is largely a pest that attaches itself to the base of needles, any tree part bearing twigs and needles is regulated. Regulated articles include branches, boughs and uncomposted, chipped/shredded/ground parts that include twigs and needles.

Hemlock and tiger-tail spruce logs, lumber and firewood are conditionally regulated if there are twigs and needles attached to those items.

The quarantine establishes a regulated area consisting of Allegan, Oceana, Ottawa and Muskegon counties. Movement of regulated articles from the regulated area to all other counties in Michigan is prohibited except under a compliance agreement issued by MDARD specifying treatments and other phytosanitary measures determined to mitigate the risk of spread of HWA The quarantine also prohibits movement within the regulated area except under a compliance agreement.

The HWA Interior Quarantine was approved by Director Jamie Clover Adams on June 5, 2017 and goes into full effect 30 days later on July 5, 2017. A copy of the quarantine is enclosed.

Questions regarding the quarantine may be directed via email to Mike Bryan, Plant Industry Specialist, at bryanm@michigan.gov or by fax to (517) 335-4540.


Robin Rosenbaum, 

Plant Industry Section Manager Pesticide and Plant Pest Management Division


This announcement was originally created by the State if Michigan Department of Agriculture and Rural Development and is being distributed by the Great Lakes Timber Professional Association (GLTPA)