The Register Citizen (Torrington, CT)
‘We are about to surrender to knotweed’
Invasive plant causing safety concerns
GOSHEN — An invasive species that can grow up to 10 feet high is causing traffic safety concerns as it encroaches on road easements and blocks drivers from seeing oncoming cars.
Town leaders learned about the rapid spread of Japanese knotweed at the December meeting of the Northwest Hills Council of Governments.
One intersection affected by the weed was in North Canaan, where First Selectman Charles Perrotti said “there could have been some close calls,” between oncoming traffic.
The intersection of Route 44 and Greene Avenue was particularly bad, Perrotti said Wednesday.
With the help of the state Department of Transportation and a local expert, the sight lines are much better now, he added.
Local expert Thomas Zetterstrom, of Canaan, brought a prop along when he presented information about knotweed to the regional council.
He lifted up a branch of the invasive species to show members what the plant looked like in the winter. It still held leaves and was reddish brown.
“It’s highly visible in the fall, it turns golden brown,” Zetterstrom said. But the plant is at its showiest in the late summer, he added, when it’s covered with white flowers.
The late-season flowers “lured plantsmen to bring it to the United States in 1890 from Europe,” he said.
Knotweed is not called an invasive species for nothing. It has grown so thickly along some of the Housatonic River banks, Zetterstom said. The river was designated as National Wild and Scenic River in 2016. The fast-growing weed is now he dominant plant along some of the river banks.
“It precludes all native plants,” he said, and invades areas “where amphibians would be,” if there had not been extreme changes to their habitat.
To find out how much knotweed had spread along areas of the scenic river not accessible by foot, a group of 10 volunteers paddled down the river last summer, Zetterstrom said. They surveyed both sides of the river and found
“It was manageable.. but it was on both sides,” of the river, he said.
That’s in contrast to areas along Route 44, he said. “It’s everywhere. We are about to surrender to knotweed,” Zetterstrom noted.
“Roadside mowing keeps it from blossoming,” he told the council. “But it doesn’t stop it.”
Zettersrom also said that mowing the plant can transfer root fragments caught in the mower’s tires to other areas.
“With less than 0.5 inches of root, it can propagate,” he said.
“He took me out to Segalla Field,” on Clayton Road, Perrotti said. “I saw (knotweed) and I didn’t know that’s what it is.”
Ridding the area of knotweed is a must, Perrotti said.
“It’s much better if they treat it,” he said.
The most environmentally friendly option, Zetterstrom told the group, is the practice of placing an opaque “blanket” over patches of knotweed that have been cut to ground level.
The blanket “keeps sunlight and water out for up to five years, ultimately killing the plants,” according to the Housatonic Valley Association’s website.
“It’s a long and labor intensive process, but it keeps dangerous herbicides out of the nearby river,” the information notes. The association reports that more than 8,000 square feet of knotweed has been successfully removed by the blanket method.
More information about how to control knotweed, or how to volunteer to help remove it from river banks, can be found through the group’s website at: hvatoday.org.
Information on how to manage other invasive species can be found through the Connecticut Invasive Plant Working Group’s website, or by calling Donna Ellis, the University of Connecticut’s Senior Extension Educator, at 860-4866448.