6 ms·

The dual nature of Japanese Knotweed

41 points by dnetesn 2y ago

blackeyeblitzar 2y ago
This thing is incredibly invasive and is all over the Northwest and other parts of America near waterways. It spreads underground like bamboo. It’s super expensive to get rid of, because it you have to fight it for many years consistently for it to die out. And even then you may just be unlucky enough for it to spread into the area again from some adjacent area or from fragments in the water.
janice1999 2y ago
It's stupidly irresponsible to encourage people to forage Japanese Knotweed in countries where it is a major threat to existing ecosystems. Even small fragments on shoes or in water can cause outbreaks. That's why dealing with contaminated soil is extremely expensive. https://emmaplusthree.com/home/japanese-knotweed-understanding-its-spread-and-how-to-prevent-it/ https://emmaplusthree.com/home/japanese-knotweed-understandi...
pclmulqdq 2y ago
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."
- hosh 2y ago
  There are many plants that have survival adaptations like that. The question is: what are the other animals that would normally eat it and keep it in check?
  - fredley 2y ago
    Lava flows?
    - hosh 2y ago
      According to this article: > 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-japanese-knotweed https://www.taylor-weed-control.co.uk/news/post/what-eats-ja...
      - zukzuk 2y ago
        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.
  - pclmulqdq 2y ago
    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.
    - hosh 2y ago
      There are probably some kind of microorganism and insects native to the US that would like to eat them.
hosh 2y ago
I find it interesting that many permaculturists would include "invasive" species in their designs. (What makes something invasive has more to do with few, if any, ecological links to other species within the area). Anything from horseradish, asparagus, to autumn olives, sea buckthorne, jujube. 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.
- throwup238 2y ago
  > The mayor of Jerome, AZ seeded them to help stop erosion in Jerome 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.
  - hosh 2y ago
    But, if they develop relationships with other species within that ecology, then those form networks that allows participation in the local ecology. They would no longer be invasive.
    - throwup238 2y ago
      That doesn't help all the plants they displace or drive extinct altogether. That's why they're called invasive, not because they're incapable of forming new ecological relationships.
      - 2y ago
exDM69 2y ago
Previous owner of my property planted this damn plant here in two separate patches. 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.
- rimunroe 2y ago
  I believe cutting every day is counter-productive because it causes it to spread. I’m in Massachusetts. The strategy we’re using is cutting once in early summer. Then we let it grow (completely undisturbed) until right after it flowers in early fall. At that point we cut and inject concentrated glyphosate into the stumps. The idea is to inject the herbicide right as the plant is drawing stuff back into its root system for the winter.
  - bjacokes 2y ago
    I've read about this strategy and am giving it a shot this year. 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.
  - exDM69 2y ago
    I do not cut it. I dig out any shoots and as much root as I can as soon as they appear above ground. For the other patch, I did just what you say, cut, herbicide and then covered it.
fatnoah 2y ago
It is a very tenacious plant. I had exactly one stalk grow to 3 feet in a mulched area of my yard. I didn't think too much about it because I didn't know what it was and hadn't heard of it. While testing a trial of a plant identification application, I successfully identified it. 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.
- krunck 2y ago
  I had a situation similar to yours. I was able to eliminate the single plant by chopping it out every time it popped up. No glyphosate needed.
  - foobarian 2y ago
    At some point even highly invasive plants like JK have to respect laws of thermodynamics. You get it eventually! 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.
    - exDM69 2y ago
      I'm starting to suspect that this plant either violates the laws of thermodynamics, works by geothermal energy it sucks from its roots which seem to go down to the tectonic plates, or perhaps by radioactive decay of radon in the ground.
- zikduruqe 2y ago
Modified3019 2y ago
When you get to the point where you realize a herbicide might be nice, but aren’t set up for spraying or dealing with potential drift (droplet size is important, a mist means chemical is floating away to touch something you don’t want), look into stem injectors which is a common method to limit risk. Keep in mind timing will be important though. 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.
err4nt 2y ago
It just occurred to me - we only call these 'invasive' not because they invade nature, but because they invade the spaces we as humans have carved into nature. If our presence wasn't there, perhaps the natural ecosystem wouldn't have space or room for some of these species to enter, but because of human activity, a space is carved out for these other species to grow in, and that's what causes us the stress. 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.
- resizeitplz 2y ago
  Invasive species aren't 'invasive' for invading human space. They're invasive for invading other species space.
- enlyth 2y ago
  The term "invasive species" never made sense to me. It just means something can evolutionary outcompete other things, because it is better at utilizing that environment. Basically putting a label on things we don't like.
  - cmyr 2y ago
    This is definitely true, but there is a useful distinction between the usual evolutionary competition between species in an ecosystem and the very sharp situation of an ecologically novel species being introduced into that ecosystem and out-competing the incumbents, and 'invasive species' is the best term we currently have for this second case.
  - ppseafield 2y ago
    We don't like it because it can cause widespread damage to the ecosystem, not just to us. Life didn't evolve in a vacuum, and the balance of natural ecosystems can be fragile. > [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-invasive-voracious-and-resilient-theyre-also-spreading-180973824/ 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-biodiversity-as-well-as-crops-120066 https://theconversation.com/feral-pigs-harm-wildlife-and-bio...
fmajid 2y ago
Here in the UK, it's considered incredibly bad news because it destroys the foundations of houses, and is well-nigh impossible to eradicate.
- throw46365 2y ago
  This is why when you see a house on rightmove that has heavy plastic tarpaulin over a considerable patch of the garden, you ask questions... Bit of an issue in some of the areas I've been looking. 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.

41 points by dnetesn 2y ago

This thing is incredibly invasive and is all over the Northwest and other parts of America near waterways. It spreads underground like bamboo. It’s super expensive to get rid of, because it you have to fight it for many years consistently for it to die out. And even then you may just be unlucky enough for it to spread into the area again from some adjacent area or from fragments in the water.

janice1999 2y ago

It's stupidly irresponsible to encourage people to forage Japanese Knotweed in countries where it is a major threat to existing ecosystems. Even small fragments on shoes or in water can cause outbreaks. That's why dealing with contaminated soil is extremely expensive. https://emmaplusthree.com/home/japanese-knotweed-understanding-its-spread-and-how-to-prevent-it/ https://emmaplusthree.com/home/japanese-knotweed-understandi...

pclmulqdq 2y ago

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."

hosh 2y ago
There are many plants that have survival adaptations like that. The question is: what are the other animals that would normally eat it and keep it in check?
- fredley 2y ago
  Lava flows?
  - hosh 2y ago
    According to this article: > 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-japanese-knotweed https://www.taylor-weed-control.co.uk/news/post/what-eats-ja...
    - zukzuk 2y ago
      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.
- pclmulqdq 2y ago
  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.
  - hosh 2y ago
    There are probably some kind of microorganism and insects native to the US that would like to eat them.

hosh 2y ago

I find it interesting that many permaculturists would include "invasive" species in their designs. (What makes something invasive has more to do with few, if any, ecological links to other species within the area). Anything from horseradish, asparagus, to autumn olives, sea buckthorne, jujube. 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.

throwup238 2y ago
> The mayor of Jerome, AZ seeded them to help stop erosion in Jerome 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.
- hosh 2y ago
  But, if they develop relationships with other species within that ecology, then those form networks that allows participation in the local ecology. They would no longer be invasive.
  - throwup238 2y ago
    That doesn't help all the plants they displace or drive extinct altogether. That's why they're called invasive, not because they're incapable of forming new ecological relationships.
    - 2y ago

exDM69 2y ago

Previous owner of my property planted this damn plant here in two separate patches. 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.

rimunroe 2y ago
I believe cutting every day is counter-productive because it causes it to spread. I’m in Massachusetts. The strategy we’re using is cutting once in early summer. Then we let it grow (completely undisturbed) until right after it flowers in early fall. At that point we cut and inject concentrated glyphosate into the stumps. The idea is to inject the herbicide right as the plant is drawing stuff back into its root system for the winter.
- bjacokes 2y ago
  I've read about this strategy and am giving it a shot this year. 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.
- exDM69 2y ago
  I do not cut it. I dig out any shoots and as much root as I can as soon as they appear above ground. For the other patch, I did just what you say, cut, herbicide and then covered it.

fatnoah 2y ago

It is a very tenacious plant. I had exactly one stalk grow to 3 feet in a mulched area of my yard. I didn't think too much about it because I didn't know what it was and hadn't heard of it. While testing a trial of a plant identification application, I successfully identified it. 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.

krunck 2y ago
I had a situation similar to yours. I was able to eliminate the single plant by chopping it out every time it popped up. No glyphosate needed.
- foobarian 2y ago
  At some point even highly invasive plants like JK have to respect laws of thermodynamics. You get it eventually! 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.
  - exDM69 2y ago
    I'm starting to suspect that this plant either violates the laws of thermodynamics, works by geothermal energy it sucks from its roots which seem to go down to the tectonic plates, or perhaps by radioactive decay of radon in the ground.
zikduruqe 2y ago

Modified3019 2y ago

When you get to the point where you realize a herbicide might be nice, but aren’t set up for spraying or dealing with potential drift (droplet size is important, a mist means chemical is floating away to touch something you don’t want), look into stem injectors which is a common method to limit risk. Keep in mind timing will be important though. 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.

err4nt 2y ago

It just occurred to me - we only call these 'invasive' not because they invade nature, but because they invade the spaces we as humans have carved into nature. If our presence wasn't there, perhaps the natural ecosystem wouldn't have space or room for some of these species to enter, but because of human activity, a space is carved out for these other species to grow in, and that's what causes us the stress. 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.

resizeitplz 2y ago
Invasive species aren't 'invasive' for invading human space. They're invasive for invading other species space.
enlyth 2y ago
The term "invasive species" never made sense to me. It just means something can evolutionary outcompete other things, because it is better at utilizing that environment. Basically putting a label on things we don't like.
- cmyr 2y ago
  This is definitely true, but there is a useful distinction between the usual evolutionary competition between species in an ecosystem and the very sharp situation of an ecologically novel species being introduced into that ecosystem and out-competing the incumbents, and 'invasive species' is the best term we currently have for this second case.
- ppseafield 2y ago
  We don't like it because it can cause widespread damage to the ecosystem, not just to us. Life didn't evolve in a vacuum, and the balance of natural ecosystems can be fragile. > [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-invasive-voracious-and-resilient-theyre-also-spreading-180973824/ 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-biodiversity-as-well-as-crops-120066 https://theconversation.com/feral-pigs-harm-wildlife-and-bio...

fmajid 2y ago

Here in the UK, it's considered incredibly bad news because it destroys the foundations of houses, and is well-nigh impossible to eradicate.

throw46365 2y ago
This is why when you see a house on rightmove that has heavy plastic tarpaulin over a considerable patch of the garden, you ask questions... Bit of an issue in some of the areas I've been looking. 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.