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Conservation Commission hears primer on Japanese knotweed control; presenter outlines chemical and nonchemical options
Summary
Randy Prostak briefed the Charlemont Conservation Commission on Japanese knotweed control, recommending a pilot site and describing timing and products (cut in late May/early June; foliar application with Aquaneat or glyphosate 5.4 during a six-week window). He said one-year control of about 80% is possible but repeat treatments are typical.
Randy Prostak gave the Charlemont Conservation Commission a detailed overview of techniques to control Japanese knotweed and urged the town to consider a pilot project in one location before scaling up across the watershed.
Prostak described both chemical and nonchemical approaches. He recommended cutting knotweed in late May to early June to weaken regrowth, then applying a foliar herbicide—he mentioned Aquaneat or glyphosate 5.4—during a roughly six-week treatment window when plants are flowering and leaves are still green. "You can control 80% in one year," Prostak said, but he advised repeating treatment in the second and third years to suppress regrowth.
He told commissioners that Roundup Pro appears on a "sensitive areas materials list" and said public concern over glyphosate products often focuses on surfactant ingredients such as POEA, which he said are toxic to fish. Prostak also described a nonchemical approach used in some cases: layering woodchips, plastic, then woodchips to block regrowth and protect the plastic with a top layer of chips.
Prostak recounted that a previously funded Hawlemont riparian-buffer/knotweed project did not proceed and said Sheila Litchfield and advocates in the Mad River Valley, Vermont, had discussed coordinated control across the Deerfield River watershed. Agricultural Commission Chair Nate Bellows, present at the meeting, said he did not view the work as an agricultural-commission issue.
No vote or formal program commitment was recorded at the Aug. 14 meeting; commissioners received the primer as informational as they consider local options.
