Japanese knotweed (Polygonum cuspidatum; Latin synonym Fallopia japonica) is indisputably a major nuisance in the urban forest. NYC Parks Natural Resources Group has documented extensive research and control methods they’ve used, in partnership with the Bronx River Alliance and other entities, to combat knotweed along the Bronx River and in other natural areas in the City’s five boroughs.
Regardless of what combination of chemical and mechanical means are employed, control of Japanese knotweed is widely acknowledged to be imperfect at best. While we can and should manage its presence in our urban forests, this plant is here to stay.
Why and how is Japanese knotweed so successful at colonizing the most degraded sites? Why is it so hard to control? And what are some of the positive attributes of the plant that you might not hear much about? In this piece, Council member Laura Wyeth, a horticulturist with a particular interest in weed science, explores some of what makes Japanese knotweed unique.
Japanese knotweed is a plant caught up in the polarization of our times. Both its virtues and its malevolence have been inflated in the public imagination, and it is at once known as both miracle drug and botanical monster. In Canada, a nation not prone to paranoia, it has been described as “a demon weed so relentless, bloody-minded and destructive, it’s been called the terrorist of the plant kingdom.” Strong words for a creature with no teeth, claws, or toxicity to humans. Internet herbalists tout its miracle cancer-fighting properties with equal hyperbole. Yet with this plant, the quiet facts are more interesting than the hype.