If it’s knot-weed, what is it? It’s not bamboo, for one thing, though it grows like it. It is the very thick shrub which is blooming in thin white arches right now along roadsides.
Japanese knotweed (Mexican bamboo) is in the buckwheat family. Years ago it was planted on purpose for vegetative barriers, but not any more! It is impossible to keep it from spreading where you don’t want it. Mowing it year after year does not kill it.
A summer resident, a medical doctor from Massachusetts, knows what it has done to their river and stream banks — totally lining them with thick growth that crowds out all native species and blocks the view of the water. He says that 15 years ago, Vermont was in the same state of invasion as we are now in the Adirondacks, and that most of the river and stream banks there are bulging with it now. Our forest preserve is almost free of it so far, and we have a chance to keep it that way if we work on controlling it in the surrounding areas.
This heroic man has been working for years when he visits here to recruit volunteers, to document where Japanese knotweed and two other kinds are, and to find funding to hire certified herbicide applicators to shoot the stems, with “guns” calibrated to inject a certain amount of glyphosate, one stem at a time. When done in late summer and fall after the plant flowers and before frost, the substance is pulled down into the roots, and up to 95 percent are killed the first year. A second application to the few remaining plants is needed the next year, and maybe in the third year. Glyphosate interferes with critical enzymes in the growing plant which are needed for building proteins, and degrades quickly in the ground. It can kill many other plants too, but this injection system affects only the injected plants.