Conservation district fights spread of knotweed

BESSEMER - The Gogebic Conservation District is gathering landowner information on an effort to eradicate knotweed, an invasive plant species that can penetrate house walls and floors.

Jim Finley, district administrator, said the GCD was awarded a grant from the Michigan Department of Natural Resources to fight knotweed in the western Upper Peninsula.

In seeking information for the effort, Finley has mailed letters to those who may have knotweed infestations.

The GSD and U.S. Forest Service spent last summer mapping knotweed infestations in the old mining zone stretching from Ironwood to Wakefield.

Ron Zaleski, GCD director and invasive species coordinator, said more than 30 clumps were located, some covering areas of hundreds of square feet.

Quite a few of the clumps are close to houses.

Some people have planted the knotweed, thinking it was a form of bamboo, Zaleski said.

People who'd like to view a knotweed infestation can look on the south side of Ayer Street, where Luxmore Street intersects.

The Asian plants grow roots as deep as 10 feet and send out underground stems that may shoot out 60 feet or more.

The plant can grow through pavement and can penetrate masonry and concrete foundations.

The bamboo-type plants have shoots that can grow 15 feet tall. The many shoots can form a dense jungle that crowds out all other plants.

In late summer, the white or cream-colored flowers may buzz with bee activity.

Along streams, it forms thickets along the banks that can make them almost impassable and cause erosion damage.

There are no known natural enemies and the most effective control is herbicides.

A weed team will apply the herbicide locally. The GCD letters seek permission for application of the herbicide.

People who have knotweed plants but weren't mailed letters should contact the conservation district at 906-663-4512 or email [email protected].