Here in the late Spring, we’ve begun our annual battle to contain a verdant bed of Japanese Knotweed. Of all of the hours I spend brushcutting around Little Farm, probably ninety percent goes into trying to keep the Knotweed in some semblance of containment. The plant is now nearly ubiquitous here in Maine and for that matter throughout the Northeast. Early every Fall, its white blossoms broadly carpeting roadsides and empty lots make it clear just how widespread Knotweed has become. Truly, Knotweed is the Kudzu of the northern U.S.
Knotweed is actually quite a lovely plant. Growing quickly to 5-8 feet or more with thick sheaves of broad, dark green leaves and clouds of those lovely white blossoms in the early Fall, Knotweed beds are so dense that they shade out almost all other plant life. If one wants a dense wall of lovely, uniform, deep green vegetation, Knotweed is your plant. Very early Knotweed shoots make a surprisingly-passable ersatz rhubarb pie. People have used Knotweed leaves and sap for a variety of home medications. Bees love the Knotweed flowers as one of their very last pollen sources. And I have to say that I never find ticks anywhere near the Knotweed beds.
The problem with Knotweed is that it doesn’t know when to quit. Knotweed is a phenomenally vigorous and aggressive plant. It develops tough, deep, woody roots and propagates both through tillers and rhizomes (the lateral roots). Any part of a Knotweed plant that touches the ground will send out roots. The rhizomes are not the thin, spindly things we see on many plants. They can be as tough and tenacious as the roots themselves. In addition, Knotweed can vegetatively propagate; a tiny fragment of any part of the plant left on the ground can generate a new healthy plant. I was interested to learn that cutting down Knotweed without a permit is against the law in the Republic of Ireland precisely because of widespread vegetative propagation from even dust-sized plant fragments.
If you are not familiar with the plant, Knotweed is an invasive species bearing an uncanny resemblance to bamboo, but without bamboo’s sturdy, useful stems. Looking for a fast-growing, deeply green, heavily-leaved landscape plant, the naturalistic gardeners of England’s late Georgian period brought Knotweed to England from Asia in 1825. It came to the U.S. in the late 19th Century coincident with the growth of the super-wealthy Robber Barons and the desire for “the English Look” in the gardens of their estates. Full-time gardeners can manage the stuff, but the operative word here is “full-time”.
Knotweed, along with Poison Ivy, Multiflora Rose, and crabgrass, are on my short-list of least-desired plants. We have all four in abundance here, but Knotweed is the one that doesn’t know its place and keeps trying to take over everything. If you have ever watched the 1962 classic British SciFi film; “The Day of the Triffids”, a story about an inexorable, sentient, extraterrestrial plant species that tries to overgrow an isolated country home and eat the people inside, well, you’ll know how I feel about Knotweed.
Our predecessors here at Little Farm waged a 20-year battle and finally expelled most of it from the main property (although, in spite of our best efforts, every year, 15-20 plants still poke their heads up underneath one of our grape arbors). Our property south of Lambs Mill Road is another matter. If not whacked down to the stub 5-6 times a year, the Knotweed that lines the road front there will actually begin to grow out over the road itself.
Knotweed has even invaded Canada. A Ranger in Algonquin Provincial Park in Ontario has told us of their ongoing (and largely futile) battles to eradicate the plant, found even in the deep, roadless areas in the far north of the Park’s million acres. On one one-acre patch, they cut repeatedly throughout a Summer, then sprayed the roots with glyphosate, then covered the entire acre with a thick plastic membrane. When they came back early the next year, they found Knotweed shoots coming up through the melting Spring snow. It had shrugged off the herbicide, penetrated a heavy landfill liner, and grown up through as much as three feet of snow. I wish our tomatoes had 10% of that vigor!
Notwithstanding the Algonquin experience and plenty of other similar experiences, Glyphosate seems to be the tool of choice for the Public Works crowd. Our town wants us to stop cutting so their pesticide applicator can spray the fully-grown plants when they flower - the time when they are theoretically most vulnerable. Bees love Knotweed pollen, but they really don’t like Glyphosate, and we want to protect Nancy’s hives as well as the hives of our neighbors. Fortunately in Maine, a property owner can opt out of right-of-way spraying – something we have chosen to do. The Town will not be happy with us, but the bees will.
True, I am condemning myself in perpetuity to my multiple Spring/Summer/Fall brushcutter forays. But what the heck; it’s good exercise.
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