New Hemlock Quarantine Possible

It’s a tiny forest pest that is wreaking havoc across the Appalachian Mountain region and one that could cause the same kind of devastation in Michigan if we’re not careful.

It’s called the hemlock woolly adelgid (HWA), a small aphid-like, sap-sucking insect that is responsible for killing thousands of hemlock trees. It’s difficult to find due to its small size, but can begin killing trees as early as 4 years after infestation. The first reported sighting was near Richmond, VA in 1951. By 2005 it had spread to 16 states from Maine to Georgia.

It has been recently identified in west Michigan; first noticed in Muskegon county, but has also been found in nearby Allegan and Ottawa counties. An import quarantine is already in effect for Michigan, meaning that hemlock cannot be brought into Michigan from an infested state. However, since it has been determined that HWA is in several Michigan counties, an in-state quarantine is being considered. This would mean that movement within Michigan would be regulated, especially within the quarantined counties.

With the estimated 170 million hemlock trees in Michigan, including the virgin hemlock forest at Porcupine Mountains State Park, extra caution is a good thing.

 

Michigan is preparing to enact interior quarantine due to invasive hemlock tree pest

A recent outbreak of the pest within the state has prompted new legislation which will restrict the movement of hemlock products within Michigan in an effort to control this invasive pest.

Adelgid infested hemlock branches. Photo credit: USDA Forest Service - Region 8 - Southern, USDA Forest Service, Bugwood.org

Adelgid infested hemlock branches. Photo credit: USDA Forest Service – Region 8 – Southern, USDA Forest Service, Bugwood.org

 

Over the last several years, in reaction to the outbreak of hemlock wooly adelgid in forest stands across the eastern U.S., Michigan banned the shipment of hemlock trees and wood with bark into the state. However, a recent outbreak of the pest within the state has prompted new legislation which will restrict the movement of hemlock products within Michigan in an effort to control this invasive pest.

The exotic hemlock wooly adelgid insect was first identified in the eastern U.S. in early 1950s. It has systematically spread throughout the Appalachian region and is devastating the hemlock tree forest resource by the thousands. In an effort to help protect the estimated 170 million hemlock trees in Michigan, a ban or quarantine on bringing hemlock nursery stock and wood products with attached bark into the state has been in place for some time and was last revised in 2014.

In spite of the efforts to keep this destructive forest pest out of the state, an infestation has been identified in central West Michigan. First noticed in Muskegon County, closer inspection has identified colonies of the tiny sap feeding pest in neighboring Ottawa and in Allegan Counties as well.

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Pale crown appearance with no new growth indicates this tree is under severe attack from Hemlock Woolly Adelgids. Photo credit: James Johnson, Georgia Forestry Commission, Bugwood.org

In an effort to control or slow this tree-killing pest, the Michigan Department of Agriculture & Rural Development (MDARD) solicited public comment on a proposed hemlock woolly adelgid interior quarantine. The original draft stated that “the proposed quarantine, movement of hemlock nursery stock, branches, boughs, uncomposted chips, logs and firewood would be regulated. Specifically, movement out of, or within, the three county area would be prohibited except under compliance agreement issued by MDARD. The proposed regulated area includes Allegan, Muskegon and Ottawa counties.” Other counties may be added as the need arises to further limit the spread of hemlock woolly adelgid.

If the quarantine is enacted, the movement of hemlock trees, boughs, firewood, logs or limbs will be prohibited without a compliance agreement. This restricted movement would include movement within these counties from site to site. (Note: A compliance agreement are actions jointly taken by both producers and the State of Michigan to ensure hemlock nursery stock and wood products are free of the adelgid insect.)

For more information on the hemlock wooly adelgid, Michigan State University Extension has a bulletin available. Extension Bulletin E-3300  details the life cycle and highlights the negative impacts from this invasive killer with some available treatment options should landowners identify adelgid colonies in their trees.

In addition, people interested in becoming actively involved in identifying new infestations of this and other potential forest pests are encouraged to become involved in the MSU Extension Eyes on the Forest program by becoming a sentinel tree volunteer.

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