The dual nature of Japanese Knotweed
worldsensorium.com
worldsensorium.com
As someone loathe to use chemicals, I thought perhaps that the tenacity of the plant was overhyped, so I simply pulled the stalk out of the ground. Over the next several months, I'd notice 3-4 new stalks popping up each week over a roughly 15 foot radius area. That continued through the next spring when I finally decided enough was enough and got the glysophate.
From June through winter (I'm in the northeast US), I'd let a plant grow for a week or two and then spray it with the glysophate and leave the plant in place. I did this for the entirety of the following year as well. Now, in year 3, I finally have no more shoots popping up, and can't begin to imagine what managing a true infestation looks like.
On that note, the dried knotweed stalks are fun to burn because their bamboo-like segments are divided by a membrane that seals them shut, so they pop quite satisfyingly. Our kids were sad that they ran out of it at some point after a while harvesting the stalks behind our yard.
https://www.eattheweeds.com/japanese-knotweed-dreadable-edib...
They were like 5 feet tall, and I'm pretty certain they could star in a b-grade horror movie.
here's the plant (but the wikipedia images don't do it justice):
https://en.wikipedia.org/wiki/Verbascum_thapsus
EDIT better images: https://duckduckgo.com/?t=ffcm&q=Verbascum+thapsus&ia=images...
I don't like using it myself but it's better than both other options; the invasive choking out everything else or indiscriminately spraying.
https://emmaplusthree.com/home/japanese-knotweed-understandi...
There's a particular case of the Tree of Heaven, an aggressive tree species that can live on land polluted by copper tailings. They get everywhere, grow back more prolific if you tried pulling them, and do not have a pleasant odor. The mayor of Jerome, AZ seeded them to help stop erosion in Jerome. And it worked.
Even running bamboo can be managed -- the key is to consistently harvest the edible sprouts.
This demonstrates the power of regeneration in living systems, be they ecologies or individual plants. It's aligning this regenerative power with the interests of human civilization that can restore wastelands, reverse desertification, while yielding something useful for humans.
Kudzu, cheatgrass, knotweed, tree of heaven, saltcedar, crown vetch, english ivy, giant reeds, iceplant... the list goes on and on. It's absolutely ridiculous how many invasive plants have been spread intentionally to control erosion. I found out later in life that most of the iconic plants I associate with the places I grew up are invasive.
If there are interactions, then the ecologies start merging and adapting. The native species can still thrive because there is participation among both old and new.
Seriously, go look at the iceplant covering California's coasts [1]. Or the himalayan blackberry all over the pacific north west [2]. Or the kudzu vine all over the south east US [3]. They smother native competitors and eliminate them everywhere they go, turning once diverse ecosystems into monocultures.
The ecosystems don't adapt, they get wiped clean of any native plants whose niche overlaps even slightly with the invader. If the native species could adapt, the introduced species wouldn't be called "invasive" but "naturalized"
[1] https://www.fiscaliniranchpreserve.org/images/Photo%201%20NP...
[2] https://extension.oregonstate.edu/sites/default/files/styles...
[3] https://upload.wikimedia.org/wikipedia/commons/4/4c/Kudzu_on...
A typical knotweed patch that I see here in Scotland is in a disturbed urban area, for example by the railway. While it might be displacing a native species that takes over ruderal sites, e.g. blackberry or gorse, it still performs its functions of urban greenery - makes habitat for birds, cleans up the city air a bit, covers up trash on the ground.
Some of the roots I've dug out had about 8cm diameter and they were tough stuff.
No you don't want this stuff even in urban wasteland.
Or growing in railroad ballast where it's can cause a very expensive clean up operation or destabilize the foundation of the railroad.
https://en.m.wikipedia.org/wiki/Pontederia_crassipes
Actually the article says it is invasive in many countries.
You have to introduce species that bridges the gap and creates those links.
To give an example with kadzu:
https://www.smithsonianmag.com/science-nature/true-story-kud...
Tldr: kadzu turns out not to be as invasive as people thought, and the kadzu bug has been eating its way through them.
I'm on year four trying to get rid of it and it's still showing signs of vitality. If I let my guard down, it's gonna be back with a vengeance in a year or two.
I dug out about 600 kg of roots from about 6 square meter area and have culled every shoot every day from the patch almost every day for four years.
The other patch was first treated with herbicide and then covered it with a light blocking tarp made for this purpose. It's still going after 4 years in the dark.
Please do not pick it up or mess with it. It is a terrible plant and destroys everything around it.
If I understand it correctly, the reasoning is that until the late summer, the underground root system is putting its energy towards growing the stalks and leaves, so you _want_ it to grow as much as possible. If you trim daily, you'll never let it get into the rapid growth stage where it's really depleting its energy reserves. In other words if you trimmed daily or monthly til the end of time, eventually you'd kill the plant, but it might ironically die more quickly if you trimmed monthly.
It's a bummer knowing that it'll be hard to fully eradicate it given how widespread it is in the area (I'm also in Massachusetts), but I guess there aren't really any permanent victories in life when you think about it.
For the other patch, I did just what you say, cut, herbicide and then covered it.
That's a lot of digging!
Cutting vs digging shouldn't make much of a different in terms of the plant's response to damage (aggressive spreading). It'll spread when it gets hurt either way. Also, knotweed's root system goes down down 4-12 feet so usually removing the roots isn't feasible. Frequently digging it out or cutting it will hurt the plant but it's going to be a very slow and labor intensive way to eradicate it.
When I dig out the shoots, I always try to get more than this year's growth, and hope that laws of thermodynamics will eventually prevail.
The damn thing is almost dead by now. I get a dozen shoots a week or so.
The question is: what are the other animals that would normally eat it and keep it in check?
> 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.
https://www.taylor-weed-control.co.uk/news/post/what-eats-ja...
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.
As always, take the PPE notice on the label seriously (sit down and read the entire damn thing), and always wear chemical resistant gloves and a splash guard for the face.
It is possible to kill it -- it's possibly easier to kill than Horsetail/Mare's Tail, which spreads even faster at root level and is very difficult to remove, but thankfully does not damage buildings.
Isn't it weird how we're so acutely aware of the effect of the species that invade our space, but so ignorant so often of our effect on the same spaces when we invade them?
I think I learned something valuable today chewing on this article.
Basically putting a label on things we don't like.
> [Feral pigs] are invasive and cause millions of dollars in agricultural damage each year, rooting and trampling through a wide variety of crops. They prey on everything from rodents, to deer, to endangered loggerhead sea turtles, threatening to reduce the diversity of native species. They disrupt habitats. They damage archaeological sites. They are capable of transmitting diseases to domestic animals and humans.
https://www.smithsonianmag.com/smart-news/feral-pigs-are-inv...
> Interestingly, in their native range in Europe and Asia, pigs do not cause as much ecological damage. In fact, some studies indicate that they may modify habitat in important ways for species that have evolved with them, such as frogs and salamanders.
https://theconversation.com/feral-pigs-harm-wildlife-and-bio...
That's the magic about ecosystems. They develop over aeons, and have intricate interdependencies. Many species are extremely picky about how they mate, where they lay their eggs, what they eat when they're larva, what they eat as adults etc. If you wipe out a single plant, you could wipe out an insect that exclusively feeds on it, which could wipe out some other thing that feeds exclusively on that insect. If an invasive species that threatens a single native species, this isn't just "something we don't like", it can cause a chain reaction of extinctions.
They aren't called invasive species when they have arrived on their own without human intervention and then outcompete.
Japanese Knotweed did not come to Europe and US by its own accord, it was intentionally planted in gardens from where it escaped and is now causing ecological and economical damage at a massive scale.
Calling it an invasive species is basically admitting that it was a mistake in introducing it to another environment, and also (sometimes legally) forbidding of adding any more and/or mandating destroying existing ones.
https://education.nationalgeographic.org/resource/invasive-s...
But humans are almost always the reason for the introduction of invasive species either by accident or purpose.