I had almost half an acre of this crap on my property, and still have about a quarter of an acre after thoroughly removing one big patch. There is nothing good about Japanese knotweed in the US, and everyone who forages it is part of the problem. It evolved on the sides of volcanoes, so if you cut anything off of it (or burn it), it triggers a chemical signal that encourages virulent growth from the attached rhizome. By cutting down small amounts of it, you are actually propagating it. That is the furthest thing from "environmental stewardship."
Japanese bacteria, fungi, and lava. It's nearly defenseless against the microorganisms in its ecosystem because it spent all its evolution points on growing on the sides of mountains.
> This BBC article from 2010 points out that Japanese knotweed isn't really a problem in its native country - while common, the plant "doesn't rage out of control like it does in the UK, thanks to natural predators that keep it in check".
> In Japan, knotweed has many natural predators in the form of nearly 200 insect species and a variety of fungi. Certain psyllids (plant lice) have proven to have an appetite for Japanese knotweed sap - the organisers of the Chelsea Flower Show have looked at using psyllids to keep Japanese knotweed at bay, and one species (Aphalara itadori) has even been released into the wild in an effort to combat the UK's knotweed problem.
Same with Dog Strangling Vine in Europe vs North America.
I volunteer every week helping with ecosystem stewardship here in Southern Ontario, and DSV is absolutely out of control in parks and forests. It spreads like wildfire and wraps itself around anything and everything, choking out most other plants and creating mass monoculture.
Meanwhile, in France, where I just spent a week hiking, you see the occasional vine here and there, minding its own business, acting like a well-behaved member of the forest community.
