Official seeks to take out invasive knotweed

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GUILFORD -- Brian Colleran spends his days fighting a green, leafy foe.

Vermont's Japanese knotweed program coordinator has been driving around the state, spreading the word about an aggressive, difficult-to-eradicate invasive species that has spread far and wide by Tropical Storm Irene.

But as he supervised knotweed-eradication efforts Monday along the Green River in Guilford, Colleran also sought to instill confidence in local residents who will have to carry on the battle after he departs.

"You know exactly where it is. You know exactly how to deal with it," he said. "It's an achievable goal."

The state created Colleran's position earlier this year amid concerns that Irene's flooding in late August had allowed knotweed to multiply by carrying plants downstream.

There also is a human factor: At a site off Green River Road on Monday, Colleran pointed out multiple green sprouts in a pile of dirt that had been pushed back from the riverbank.

"Every single one of those is knotweed," he said.

Linda Lembke, a member of Guilford Conservation Commission, noted that the pile may have been created in the wake of the storm.

"All of this road work that was done after Irene -- it's a big concern," Lembke added. "It's not only the river moving it. People move it."

And that's a problem, because knotweed is known as a fast-growing, dominant plant that crowds out other vegetation and "drops biodiversity by something like half," Colleran said.

After taking over, knotweed speeds erosion. Its roots, while deep, do not anchor the earth -- a point Colleran made by gently shaking an uprooted knotweed, causing large amounts of dirt to fall.

"There's nothing about this that holds soil," he said.

All of this is compounded by the fact that knotweed nurtures far-reaching subterranean connections. Pointing out several plants that were 30 or 40 feet apart, Colleran said all could be connected.

"You've got to consider each plant and 50 feet around it," Colleran said.

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That's why officials say it is critically important to deal with post-Irene knotweed growth now. On Monday, a Vermont Youth Conservation Corps crew dug relatively small knotweed plants from the soil along the Green River.

If allowed to mature, those plants "would have been a problem. This would have been intimidating, and people wouldn't have wanted to take it on," Colleran said. "Get it while it's manageable. It's volunteer-friendly, and it's property-owner friendly."

Lembke, after noticing knotweed growth in Guilford, contacted Colleran earlier this year. He coordinated an informational meeting here in May and also conducted an assessment of the Green River.

Colleran said the conservation corps workers, who will be removing knotweed in Guilford today and Wednesday, are invaluable.

"I don't know how many volunteers we would need to do what these guys are going to do in the next few days," he said.

But volunteers and residents also are a big part of the knotweed solution. Colleran said he was hired to be "a coordinator and a motivator and an educator," and he was fulfilling the latter two functions for Lembke and fellow conservation commission member Marli Rabinowitz.

"There's educational value and the inspiration to think about how you can get workers together," Lembke said. "And there's the continual understanding, for me, of the plant itself."

That knowledge, though, can be daunting. Colleran said mature knotweed plants can reach 12 feet high and are not easily destroyed.

"The plant requires three to five years of management with chemicals or five to seven years of management without chemicals," Colleran said, adding that going the chemical-free route requires cutting the plants "every month in the growing season, at least once a month."

Simply pulling large knotweed out of the ground is akin to "pulling a leaf off a tree" and does not work, Colleran said. And he warned that uprooted knotweed should not simply be tossed aside.

Pointing to a plant lying on the ground nearby, Colleran said it "would just re-root."

Such plants can be left out to dry and then burned, or they can be sent to a landfill, he said. More information on knotweed control is available at

Colleran travels often and will be moving on to Londonderry later this week. While he cannot predict the knotweed program's future, he said Vermont officials took a major step in hiring a full-time staffer to deal with an invasive species.

"I think it's a big deal that this is happening," he said.


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