By Robert Miller
Zetterstrom and his team of volunteers — the Knotweed Network — have paddled the Housatonic, then worked with the Housatonic Valley Association …
In “The War of the Worlds” the gross alien invaders — Martians, of course — ravage the cities and countryside alike, only to fall victim to the ordinary microbes swirling around in the air. Tiny things save the day.
Now, insects are helping garden-gloved human hands — and their accompanying trowels and loppers and weed whackers — in fighting against the hoard of non-native running-wild plants that can smother the local greenery.
Imported leaf-eating beetles have helped keep purple loosestrife from taking over the state’s wetlands. Imported weevils that feed exclusively on mile-a-minute vine — named for the speed at which it grows — now seem to showing up wherever the plant takes root.
“I haven’t found a new plant that doesn’t have weevils on it,” said Kathleen Nelson of New Milford, who, with the Mad Gardeners of Litchfield County — volunteers in the crusade against non-native invasives — have fought mile-a-minute vine for over a decade.
And now, the federal government may permit horticulturalists to release a Japanese insect to munch exclusively on Japanese knot weed — the bamboo-like plant that grows in thick groves, especially along streams and rivers.
“They’ve been approved in Great Britain and Canada,” said photographer Tom Zetterstrom of Canaan, who’s been leading a crusade against knot weed along the Housatonic River. “We could be next.”
And yet all this work — and it is considerable — may be undone by climate change.
This spring was unusually wet. Everything drank its fill.
“it was a good spring for all plants,” said Jeff Ward, forester with the Connecticut Agricultural Experiment Station.
Including, alas, invasives.
“I’ve seen 8-foot-tall Japanese knotweed next to 7-foot-high mugwort,” Ward said.
“I’ve seen places where I thought purple loosestrife was gone. This spring, there it was, back,” said Carole Cheah, an assistant agricultural scientist with the experiment station. “I couldn’t believe how much was out there,”
“I’m seeing Oriental bittersweet everywhere,” said Robert Gambino of New Milford, who owns Northeast Tree Pond and Turf and is helping with the fight against knot weed along the Housatonic.
Climatologists think in years to come, Connecticut will get warmer and wetter. Invasives may flourish.
“It’s all very complicated and interesting,” said Cheah, who helped supervise the release of the Mile-a-Minute weevils.
Nelson spoke last month to members of the Litchfield Hills Audubon Society about invasives.
Here are her basic rules.
“Don’t plant invasives,” she said. “Don’t give them to your friends. Remove them.”
Nelson said people now have to even be careful about buying topsoil and mulch, out of fear it may be carrying invasive plant material.
The Mad Gardeners website — www.madgardeners.com — has full pages on mile-a-minute vine, with its triangular leaves, thorny stems and ability to quickly blanket the world. There is also a good guide to invasive plants in general “Invasive Plants in your Backyard” at https://cipwg.uconn.edu/wp-content/uploads/sites/244/2016/12/Invasives_guide_2016_web.pdf
The work at controlling them is Sisyphean.
Nelson and the Mad Gardeners tore out huge amounts of mile-a-minute vines on their own. The group got grants to hire college students to help in the summer.
Nelson said, where there’s clear access to open fields, the group has succeeded are getting rid of most of the plant. But birds can carry the seeds to other spots and those seeds can live in the soil for about seven years.
It also grows nicely under the thickets of multiflora rose — another invasive. It will spread.
“There are places where we could do nothing about it,” she said.
Japanese knotweed presents its own, knotty problems. It grows from seed, but also from rhizomes — horizontal stems growing under the soil. Once it’s established in a place, its deep roots make it hard to dig up. In river systems, pieces pf the rhizomes can float downstream and find a new place to grow.
“It can grow along any roadside, any place where the soil has been disturbed,” said Bill Tingley, chairman of the Housatonic River Commission. “But rivers have a way of carrying it.”
Zetterstrom and his team of volunteers — the Knotweed Network — have paddled the Housatonic, then worked with the Housatonic Valley Association to map the many places along the river and its tributaries where the plant is growing. They also begun to educate the public about the plant and how it grows.
And, they hold out hope for the biological control that may be in the offing.
“I’ve paddled this river,” Zetterstrom said. “The landscape along it should be that of New England, not the Orient.”