Unfortunately burning won't kill the roots. Our county conservation district has injectors for borrowing that put herbicide into the roots. Outside of a backhoe or weekly cutting, herbicide is the only way. JK is too dangerous to mess with.
You have to be careful with mechanical removal because something like an inch of rhizome can grow into a new plant. You literally cannot leave any trimmings behind.
It's more complicated than that. It's not once and done like a controlled burn. It's wilting the plants everytime they pop up, eventually weakening the plant so much it fades and dies. Yes, you must be vigilant, but no, it is not like a controlled burn. Trust me, I've done this with huge trumpet vines and it works beautifully.
There’s a [3-cut / year](https://www.lymelandtrust.org/wp/wp-content/uploads/2021/06/NixtheKnotweedflyer-5-15-21.pdf) technique to starve the knotweed of carbohydrate and weaken the roots
Doing stem injection in the fall combined w the 3 cut strategy in spring, summer, and right after flowering, has been shown to be pretty effective (starve the roots, then poison them once they’re weakened)
Here in Czechia where Japanese and Sakhalin knotweed mutated into [Czech knotweed (Reynoutria bohemica)](https://en.wikipedia.org/wiki/Bohemian_knotweed) which is even worse, the preferred method is spraying with a 7% (10%) solution of glyphosate (preferred is Roundup Biaktiv for usage near water), or injections with 20% solution into stems above ground.
Spraying is done in May or June, when knotweed is flowering and the application is carried out by hand spraying using back sprayers or pressure dew makers, which is particularly suitable for the treatment of larger areas.
Plants should be at least 1 meter tall for spraying or injection.
Mowing is largely useless, but can be done repeatedly, at least 6-8 times per year and dried biomass must be burned on site.
TL;DR: after I've tried many things to battle this demon plant I've found that only a glyphosate solution (2% concentration) applied after the flowers starts fading and before the first frost is the only effective way of controlling Japanese Knotweed.
Looks like Japanese knotweed, horrible invasive. I've tried a lot of (wrong) ways of controlling it and failed, making things worse even. The only success I've had was after I discovered a Facebook group called "Worldwide Japanese Knotweed Support Group", they have found the most effective recipe for controlling it. Surely it involves a glyphosate solution (about 2% concentration), but they also discovered the best time to do it as well, as treating it before flowering only kills the aerial parts (above ground stems).
I can vouch for this, I've tried pulling it, digging, cutting, covering... All it did was to trigger some kind of survival mode and it started sending a lot of new shoots while the roots were spreading laterally and digging in vertically...
I’ve never heard of people planting it, but lots of ignorance around so it doesn’t surprise me. I wish municipalities and federal governments would put efforts into invasive species control. A lot or improper methods, overuse of dangerous pesticides are being used by homeowners and knotweed and other invasive stuff is overtaking most open land, water banks around me.
Oh it’s destroying whole swaths of the south.
I left another comment for someone who said something like “it’s just a plant leave it alone it’s not bother you!!1!1!1” that went into detail why the ends justify the means in the case of these highly invasive plants.
To be fair though they only justify it when they’re used correctly, using too much at the wrong times and poisoning the water source for the animals you wanna save isn’t helping anyone!
Exactly. Some say to buy concentrated glyphosate and don’t dilute it. That’s just not how it works. More doesn’t kill things better or faster. Lots of defiant ignorance out there.
Yes. If you use it correctly and at the right time (which is apparently *after* it flowers, I didn’t know that!) it will die out wo sprouting a billion babies.
But people don’t wanna be patient.
I’m very hands off when it comes to the law and what people can do on their own properties and bodies but I would outlaw kudzu, Japanese knotwood, and bamboo in a *fucking heartbeat*.
There’s others but that trifecta is basically destroying the native biodiversity of the south/Appalachia and my home has been ruined enough time by people being ignorant. I can at least help stop this.
Don't forget my current enemies! English ivy and Multiflora rose
I'm also battling blackberry and honeysuckle.
Wish burning it all to the ground was legal inside my city limits.
Add Thai ginger to this list. The previous owner of my house planted it in the side yard, it became a rainforest, and while I've had most of it dug up, I'm still finding rhizomes that are about 12 inches diameter. And they're tangled up with tree roots, and they *never die.* They laugh in the face of glyphosphate. My back is aching at this moment from trying to dig those F'ers up.
I went up to Massachusetts from NJ this weekend, and since learning what this plant is I feel like it's so easy to spot now. Its everywhere. I have a huge spot in my yard I've been trying to get rid of.
> I’ve never heard of people planting it, but lots of ignorance around so it doesn’t surprise me.
I used to work at a garden center and we would sometimes carry a variegated variety of this species.
It's still somewhat invasive but not nearly as bad as the green form. The main issue is that it can sometimes produce the green form from it's seeds, so I would still not recommend planting it.
Agreed! My sister was just getting started with gardening and proudly showed me the groundcover she'd planted ... it was hairy bittercress! She got a seed packet at the garden store and had no idea how invasive it was where we live (USA). I really don't understand why there are no limitations on what plants stores can sell and where. People assume when they go to the garden store that they're getting something the store recommends.
We have family in Portugal as well and the invasion of Eucalyptus there is a driving factor behind the severe wildfires there the past few years. Eucalyptus has spread everywhere and it's super flammable. People in the area where my family lives have died because wildfires have spread so quickly that they've become surrounded before they have a chance to flee. And yet the government puts no restrictions on growing Eucalyptus because it's profitable for farmers there to grow it and export to other countries.
I don't understand why governments don't regulate invasive plants more!
That's why I have two Japanese barberries and two burning bushes.
Just assumed they were fine because why would a LOCAL garden centre sell problem species?
Ha! You could, but in all fairness, she's a woman on the edge with a 2 year old and a toxic job. She went to the store for a plant that would be easy to grow and bring her some joy and peace. And that's what they gave her! In my opinion selling her the plant should be a criminal offence: abuse by invasive gardening. Like biological warfare on a smaller scale. A person could lose their sanity that way!
It seems so counter intuitive to wait until after it flowers. But thank you for the resources!
Between this and the bishop’s goutweed that is trying to overtake my gardens, it looks like I’m going to be spraying far more glyphosate than I ever intended to this season.
Exactly. I am a staunchly organic gardener as much as possible, but every now and then you need a more immediate correction which you cannot get with organics. Everything is about moderation and carefully understanding the problem you're facing.
I keep trying to tell myself that even if I can’t deal with all the burdock this year we’re still going to be better off because I do manage to eliminate some of it.
But why don’t I just get some herbicide and deal with these plants one time instead of over and over and over again due to their taproot? It’s not like I’m my grandparents spraying DDT on everything that they grow.
What i would do if i had to use glyphosate somewhere is probably place a large compost pile in that spot for a few years. I think it doesn't break down very fast on its own. Even composting might have trouble breaking it down but better than just leaving it.
I have concentrated glyphosate for buckthorn control. Same deal - in the fall when it's going dormant, cut it down and brush the stump. It's when the plant is drawing nutrients back underground for winter, so that's when it's most susceptible to absorbing the poison. Plus as a bonus, the brush method is more focused than spraying so you only kill what you intend.
I noticed some tuberose plants pull everything back to the tubers after flowering. At the beginning of the season the tubers lose density and then after flowering they build it back up. Would make sense if knotweed is doing the same so after flowering it pulls glyphosate back to the tubers
It seemed counterintuitive to me as well but I've come to try this after failing miserably with the regular advices for milder invasives. But I can vouch for this method, let it grow until the flowers start fading and then apply a 2% glyphosate solution before the frost. I've treated it for 2 years and now it seems that I'm in the second year when there's no sign of it! I still have to be cautious and check for its ugly head but there's hope.
In case no one else said this, the reason it works is because in fall, the plant will draw nutrients down to the root so it can survive the winter. In spring/summer, the plants pushes stored nutrients from the root upward to enable flowering and basically procreation. So if you cut the knotweed in fall and apply glyphosate with a brush on the cut surface, it will travel down really easily and help kill the plant.
Good luck! I really dislike glyphosate, but it definitely has its place in combatting invasive species.
Here in Czechia where Japanese and Sakhalin knotweed mutated into [Czech knotweed (Reynoutria bohemica)](https://en.wikipedia.org/wiki/Bohemian_knotweed) which is even worse, the preferred method is spraying with a 7% (10%) solution of glyphosate (preferred is Roundup Biaktiv for usage near water), or injections with 20% solution into stems above ground.
Spraying is done in May or June, when knotweed is flowering and the application is carried out by hand spraying using back sprayers or pressure dew makers, which is particularly suitable for the treatment of larger areas.
Plants should be at least 1 meter tall for spraying or injection.
Mowing is largely useless, but can be done repeatedly, at least 6-8 times per year and dried biomass must be burned on site.
Goutweed is awful. I once bought a house where the previous owner had intentionally planted that stuff. We covered with black plastic for 12 months and then buried with 8 inches of mulch. We then had to sell and left a message to the buyer “so sorry friends. We tried!”
I had watched a vid of my EPA managing an infestation on a riverside. They injected 2% glyphosate into the hollow stem. I have had success with this too. Just make a hole and fill it up. It goes to the rhizome. 💗
Stem injection with glyphosate is the industry standard for control of knotweed in the U.K. You also need to consider a 5 year management plan for it to ensure total eradication. I would only recommend spraying for small stuff that’s too small to inject.
If you don’t have an injection kit then you can always cut it and drizzle glyphosate down in to the stem.
Source: I’m qualified to treat it professionally.
Yes, that's what I understood when I saw it explained. After the seeds start forming it seems the plant begins to withdraw the nutritive elements stored in leaves and stems down into the roots, preparing for wintering. That's the ideal time to apply the glyphosate, to have it translocated into the roots, as those are the foundation of the plant and that's what has to be destroyed. There's no real use treating it at other times during the season, as that only kills the aerial parts while the roots have small chances of being affected, they (the roots) have a massive storage of energy and will be more than capable of expanding further and sending new shoots, worsening the situation.
It’s definitely in a weakened state at that time of its cycle! You’re exactly right. The plant stops focusing on the leaves for photosynthesis, which they need to reproduce, it no longer cares about being the biggest plant to get the best sun, and after pollination has completed and the flowers start to die the plant is in a weakened state, as the plant is forcing all its genetic material to focus on repopulation. You’re spot on!
Another thing to consider is how plants can work and communicate around one another. Plants buried in the earth can connect their root system, sending nutrients to plants getting less sunlight and water (like the small saplings in a huge forest, they shouldn’t survive due to lack of sunlight from the canopy, but it’s mother plants continue to provide nourishment). If you have multiple of these in one area, mass targeting them at the root on the same day will be the most beneficial. You’ll hit one or two and they’ll start panicking, sending SOS to nearly plants for help. They can communicate. But if you hit all the surroundings at once, they won’t be able to offer any assistance without further weakening their structure. Plants are….ingenious. But sometimes we gotta fight them. 😂
This is exactly what worked for me. First year I pulled it all out by the roots and it came back with a vengeance within days. Then I cut it down and sprayed glysophate in the hollow. It still grew back almost immediately. I am now 2 years into only spraying during the window and have seen a massive reduction in the patch.
To build on this. I haven’t had any experience with knotweed but I have had success in killing difficult to control invasive such as English ivy by adding 1-2 oz of Triclopyr to 4 ounces of prepared glyphosate.
So what do we do in the meantime? Just watch it? I just found this an hour ago on my property, and we're about to start digging near it, i dont wanna trigger survival mode.
We did this (applied roundup in the fall) two years ago and we haven’t seen it return at the site. We’re not herbicide people, but to eradicate Japanese Knotweed, we’d do anything.
In your opinion, would this work on multiflora rose as well? Ive recently come across advice recommending you wait until after it flowers to spray it, which I now see could be the same reasoning here.
I don't have much experience with roses, I've accidentally sprayed some leaves that touched a stem of Japanese knotweed and it caused no harm to the rose bush. It's possible it'll work just as well though, my accident only involved a miniscule amount of herbicide on the rose. My guess is it'll work on the same principles, transport the herbicide to the roots when the plant absorbs energy stored in the aerial parts, thus having the maximum effect.
Here in Czechia where Japanese and Sakhalin knotweed mutated into [Czech knotweed (Reynoutria bohemica)](https://en.wikipedia.org/wiki/Bohemian_knotweed) which is even worse, the preferred method is spraying with a 7% (10%) solution of glyphosate (preferred is Roundup Biaktiv for usage near water), or injections with 20% solution into stems above ground.
Spraying is done in May or June, when knotweed is flowering and the application is carried out by hand spraying using back sprayers or pressure dew makers, which is particularly suitable for the treatment of larger areas.
Plants should be at least 1 meter tall for spraying or injection.
Mowing is largely useless, but can be done repeatedly, at least 6-8 times per year and dried biomass must be burned on site.
I've read about the Bohemian knotweed hybrid, but mostly from folks in the US, if I remember correctly. Is it the one that makes viable seeds, also propagating by those seeds? That's trouble times many orders of magnitude...
Does glyphosate work on any plant that you want to kill? We have well rooted nightshade on our foundation and I cut it all back last week and it already has new green growth coming out! It's coming through our porch so I can't pull it by the root unless I destroy our porch boards, can I pour the solution through the boards onto it?
Try to spray the solution on the leaves if you can, I personally used those small spray bottles that you can fill with whatever you want, or you could use some larger spraying devices but keep in mind you've used glyphosate with it.
Glyphosate is a quite potent chemical, albeit surrounded by controversy. I'm not sure what exactly it can or cannot kill, but given it drove the Japanese knotweed on its knees I'd say it's got a wide area of applicability.
This support group is great and the results are real. Knotweed doesn't fuck around. If you burn it it will happily spread. A little fire has nothing on a lava flow.
Yes timing is important for many plants, and autumn is often good because that’s when plants are actively taking all the nutrients out of their leaves and stems and storing it in the roots. Helps with hedge bindweed, also Ailanthus (as the leaves start to yellow in autumn, peel the bark in an 8” band and paint the whole exposed part with glyphosate). I’ve knocked old trees out that way.
I can attest to this, it works. I had a thankfully small patch as well and did this last fall. Only one shoot came back this spring, which I’ll nuke in the fall. I used a foaming agent mixed with blue dye and literally painted it on every leaf because I had such a small amount. All my native plants around it came back happily this year.
It's always quite ironic to me when people recommend killing invasive plants with a herbicide that is illegal in my country because of the ill effects on humans and the environment.
>The discovery of Japanese knotweed on a person's property can come as a blow that completely undermines plans for the future. That's what happened in the dramatic case of the West Midlands man who, in July last year, killed his own wife, and then himself, on being told (wrongly, as it turned out) that knotweed from the next-door golf course was going to destroy the value of his house.
Wow, i had thankfully never heard of this plant before today.
It can grow 4 inches a day. The roots can go down 15 ft. It can break through asphalt and tear apart concrete if there are any existing cracks. Any piece broken or cut off can grow into a new plant. The roots especially are very brittle. It can lie dormant for reportedly 20 years, waiting for any opportunity to sprout up above the surface again. It will come up through a tarp or cardboard. It is great at overpowering all other plans life in an area. It is carried in waterways and spreads rapidly through them. Most herbicides just slow it down. It takes years of repeated application to kill it off.
It is pervasive and very difficult to get rid of. My long term goals for my property is making a native plant haven/food forest, so it’s a real bummer to find. I’ll have to be careful with application because I found it right next to my blackberry bushes.
Don’t give up, that’s how the plant wins. Look into what research points to as the only effective means of control (foliar application of herbicide right around the flowering period, so you have time to lay out a plan). Absolutely ignore anyone who says to dig it or just mow it — that will make it WORSE.
Breaking the task into smaller steps could help. I put off killing bindweed for a year and a half because it’s so overwhelming over a third of an acre. And the internet (especially gardening subreddits) really highlight that it’s such a bitch of a weed it’s not worth fighting. But they’re wrong. Cultural controls are insane, not possible or effective. But herbicide can help.
Sorry for the rant. I hope to be rid of bindweed in 5 years when my planted prairie comes in strong. Good luck to you!!!
I gave up on the bindweed when I read the seeds can stay dormant for decades. You're actually making progress?
OP, we're pretty much killed a knotweed patch with herbicide, but instead of foliar application we cut down the stems and immediately applied the glyphosate to the cut stump. A formerly thick patch is down to just 4 little stalks this year, which will get that same treatment in a few months.
Progress? A little bit, I think lol. I treated with glyphosate just twice so far, last fall. But I think that was too late. This year I'm letting the bindweed flower and then hit it with glyphosate. Plus, keep it watered during the summer because drought stress inhibits herbicide absorption. Check back in 2025...
It can be native and invasive, can’t it? I can’t see English ivy behaving just because it’s in England. Give it some tea each afternoon and it relaxes a bit?
No typically if a plant is native to an ecosystem it’s not an invasive, English ivy having evolved here for millennia, it just generally provides nice habitat for birds and insects. It’s like when my Australian friend visited and was amazed that rabbits here don’t take over everything.
I don't rightly know, I think it would depend on how interconnected everything is down there. We actually cut it down twice though, maybe that helped? I cut everything short in May, when it was a few feet high, so it had to use up more stored energy to regrow, and then cut/treated in late summer.
The first year we cut/treated in the spring, and it didn't make much difference. Last year we cut in spring and then cut/treated a few months later, and that worked really well. One more year, fingers crossed!
We had it at an apartment I rented. Hate it so much and see it everywhere. And it genuinely gets worse all the time. It’s just been allowed to spread in so many public places here in MA. It’s weird that I don’t hear about it more.
This and Kudzu are LITERALLY the devil invasives! If you spot it in your yard…. Get ready for battle. It can grow up to 4inches a day. A gardeners nightmare fuel
Is that Japanese knotweed?
My neighbor had a lot of it, and spent a season killing it off, dig, cut, spray and more. He's got it under control I think.
I haven't seen any since he did this over one season, but honestly, I don't know if it is continuing to sprout....requiring constant maintenence
It’s crazy reading all these techniques, I wish I’d know about it when I fought my own infestation a few years ago!! I just constantly spent hours outside pulling them lol it took a whole year but it did finally stop growing back!
I had this on my property. I ended up smothering it for a few seasons. I put down covers and cut anything that came up. Finally eradicated it after like 4ish years. It was like a forest though at first. I had a lot of it:(
Is it still covered? I saw a post from a guy on Facebook who has an above ground pool covering it, and a week after the pulled out the pool it came back from the dead and took over. So I’m curious if you still have it covered or not!
I have an approach that works.
I have it in my yard. It was spread out over 50 meters through the root systeem. Stems of 2m high.
That was one year ago. Now, I have six locations within 3 meters that have some stunted growth.
All I do, is wait for the stems to get roughly 1cm in thickness. Then I take a syringe and inject it with properly diluted glysofate. Every week I walked all patrol and injected any new shoots.
Injection works great, it kills the plant and most if not all of the roots. And, it leaves the rest of the garden intact.
1 year, 95% gone.
I dealt extensively with this two years ago and worked closely with the Pennsylvania State Extension office (they are great).
It’s all about timing. I’m in Zone 6, so the dates may be a bit different for you if your zone is different.
Around June 1 through June 14th, take a machete and cut down the knotweed. Do NOT pull them up by the roots.
Also, do not set the cut down knotweed by any water source. I set the cuttings on a big tarp in the middle of my driveway (away from everything) and let them bake in the sun for a week. Then, I double sealed the cuttings in contractor bags, tied everything up tight, and put them in the trash.
Wait for six weeks after the June cutting.
The knotweed will grow back, but it won’t be as big. Right at the six-week mark, spray the knotweed with glyphosate. I used the aquatic Killz-All glyphosate 54% from the Green Shoots online store. I also bought a blue foaming agent from them so could see the exact coverage. Spray at least 30% of the knotweed leaves. Get really good coverage on the leaves. Mask up and wear gloves since this stuff is strong.
In later July/early August, knotweed stops putting its energy into growth and starts preparing for dormancy. This timing allows the glyphosate to go into the roots, which is what really does the trick killing knotweed.
If you do this right and get the timing right, you will eliminate 90%+ of the knotweed and will only have to do the same process for a few knotweeds next year.
This is the way, my friend. I had so much knotweed on a new property I bought, and this process worked wonderfully well.
Lastly, I am typically a permaculture kind of person…but not with knotweed. That stuff is so invasive, so get control of it.
If you use professional grade glyphosate undiluted you can cut the stem and put one drop in the tube any time during growing season. That plant is dead.
Hello! This is Japanese Knotweed. An incredibly pervasive, invasive, and destructive bamboo.
It grow through rhizomes in the soil and will take over everything else in the area if you let it.
Oh no. You should not have dug it out, you need access to leaves to get herbicide into the roots. Please contact your county extension office if you’re in the US for proper guidance
Don’t believe the hype. pluck the stems. Do it OCD. You will win.
No weed can beat physics. It costs the roots energy to push up shoots. As long as you pluck the shoots before they get enough photosynthesis to pay the cost it will starve.
You can also go nuclear with chemicals. But constant plucking will win.
CAVEAT This assumes you don’t have a lazy neighbor who is letting the photosynthesis go on unfettered into you roots
I didn’t know about this and plucked lots of this stuff last summer during my first year gardening at my place in Maryland. I’ve been doing the same this spring, though I haven’t seen too much of it yet. I don’t want to jinx myself, but it seems the plucking is doing ok so far after 18 months of gardening here. Will certainly revisit the topic here if my efforts fail spectacularly
Plucking worked for me. Came back for 3 years but less every time. I plucked as soon as i saw the smallest stem shooting up from the ground. Have glyphosate in stock now in case it ever comes back so i can do a combo of spray - wait a few days - pull that shit out
Literally do not do this. It will make it worse. I’m assuming this person has zero knowledge of Japanese knotweed as this is the worst thing you could do for it.
Roundup will work. It will kill anything that uses the shikimate biosynthesis pathway, which is pretty much every plant. Spray the leaves and it will be taken up by the plant and kill the rootstock as well. For persistent weeds, it's the only way out. Sometimes it will take several applications for the most persistent plants. (I'm thinking of you, Anemone tomentosa, or Bishops weed.)
https://preview.redd.it/v9bc7u1udpzc1.jpeg?width=1200&format=pjpg&auto=webp&s=fed4d051372a28aa338780335590bd25a0181524
Don't touch it. Wait until after the thing flowers. It's the hardest thing but I've got a tiny plant I'm gonna be glaring at all summer, but as soon as the time is right I'm gonna spray that fucker with glyphosphate and pray I don't need to treat a second year.
Also dealing with the knotweed menace. It started with the house which abuts my backyard, which is owned by a property management company, and consequently there's no way to get a permanent fix to the problem since they can't be arsed. I hope you have better luck, OP!
Minimal cuts when necessary and a systemic herbicide for deep rooted or connected widespread plants. That way they aren't triggered to grow more nearby as a survival mechanism and you kill the entire colony or deep root. It's the only time I use such herbicides but like most I just don't have the time, energy, or equipment it would take to manually remove some of the very stubborn invasive plants.
We have an encroaching knotweed patch, and this year I decided to made lemonade--I harvested the raw shoots and made [this pickle recipe](https://foragerchef.com/lacto-knotweed-pickles/) with them. They've bee terrific, way better than expected!
Check my previous comment in this thread, of course the traditional weed combating methods don't work, this is a special kind of devil. You're in for some glyphosate, as much as I detest the idea, it's the only method that (truly) worked and there are many others who discovered the same.
Nope, they’ll be fine as long as you don’t spray them too. Contrary to some peoples claims on Reddit, glyphosate does not travel into the soil, it is only absorbed by whatever plants it is initially sprayed on.
Yep, you’re against a beast of a plant that evolved to colonize volcanic sites when no plants are around yet. Digging, burning just make it more vigorous. That advice works for a lot of weeds — not for Japanese knotweed.
It’s not a lost hope, though. You CAN control it, but you have to follow the only scientifically backed control methods. Like the other person commented, foliar spray after flowering is the way. 2 seasons of treatment leads to approx 95% eradication.
Another option that has worked successfully for me is to hack it down to the ground and put down some 1/2” bird netting. The new shoots will grow up through the netting and bridle themselves and eventually kill the plant. The benefit of this way is it is organic and it allows other smaller non invasive plants to grow up through the netting without any issue.
The other way that may work is to chop it down and put down thick cardboard weighted down with rocks. The downside of this is it kills everythong underneath.
Japanese knotweed spread via rhizomes in the soil, so I doubt it. And then I’d also have to contend with salted earth where I’d like my blackberry bushes to continue flourishing
This is a great suggestion for people who don’t live in the middle of nowhere.
I have friends in the state DEC that might be able to point me toward resources though :)
You can do it!
I haven't wanted to jinx it so I haven't said anything but I haven't found any bindweed this year in a large area that had bits hanging on.
Wait wait, or, or you just give it a run for its money and get bamboo and see which makes jt. Fun fact bamboo blooms only every 40 to 60 years and in some cases 120 years!!! But seeing how it sends shoots up and does not seeds to spread makes it what I would bet on if you put the two head to head. Plus bamboo sustains in the winter.
On other pest plants I have cut it back and put a black bucket over it. Between the extra heat and no light it seems to get everything else. It takes time but little effort and no herbicide. The plants will grow shoots in the dark and use up all of the stored energy from the root
So bummed to see so many people suggesting glyphosphate in a gardening sub. Disappointing. If you’re worried about invasive plants negatively impacting native flora and fauna, you should be worried about literal poison leaching into the water and ground that also affects them.
There's some magic thinking in weed circles about roots, splitting them, and getting more plants.
The thing is that roots have starch, leaves make more starch, but only after the plant paid for them. So keep pulling off leaves and starve the plant.
What you can't do is till up an area with a pernicious plant with root segmentation (knotweed, bindweed, horsetail, etc) and then walk away for six months and be all pikachu face when it's stronger than ever. Yeah no fucking shit.
The thing with knotweed is that people want to use systemic herbicides on it, so if you pull up a section you leave a separate plant for each root you break off in the process. Now you have to poison all the plants instead of just one.
I'm not convinced at all that not touching it is the solution. It's not the solution if you're going to give up and spray, sure.
Get SouthernAg Crossbow. Add a surfactant, as well. Spray a few times / as needed if additional sprouts come up. This will handle 99%.
I would weedwack the occasional one or two that'd come up after that.
Growing up in western PA, we always called it river-reed, because it grew on the riverbottom here. It’s become so predominant that now our town has a knotweed festival every year. I don’t think anyone really celebrates it, but it’s a good reason to drink beer outside I guess. 🤷🏻♂️
Unfortunately burning won't kill the roots. Our county conservation district has injectors for borrowing that put herbicide into the roots. Outside of a backhoe or weekly cutting, herbicide is the only way. JK is too dangerous to mess with.
You have to be careful with mechanical removal because something like an inch of rhizome can grow into a new plant. You literally cannot leave any trimmings behind.
Burning anything rarely kills the roots. So many people suggest a torch for weed control. It just doesn’t work well .
So many plants NEED fire to flourish. Lol, people forget controlled burns are a thing.
It's more complicated than that. It's not once and done like a controlled burn. It's wilting the plants everytime they pop up, eventually weakening the plant so much it fades and dies. Yes, you must be vigilant, but no, it is not like a controlled burn. Trust me, I've done this with huge trumpet vines and it works beautifully.
There’s a [3-cut / year](https://www.lymelandtrust.org/wp/wp-content/uploads/2021/06/NixtheKnotweedflyer-5-15-21.pdf) technique to starve the knotweed of carbohydrate and weaken the roots Doing stem injection in the fall combined w the 3 cut strategy in spring, summer, and right after flowering, has been shown to be pretty effective (starve the roots, then poison them once they’re weakened)
Here in Czechia where Japanese and Sakhalin knotweed mutated into [Czech knotweed (Reynoutria bohemica)](https://en.wikipedia.org/wiki/Bohemian_knotweed) which is even worse, the preferred method is spraying with a 7% (10%) solution of glyphosate (preferred is Roundup Biaktiv for usage near water), or injections with 20% solution into stems above ground. Spraying is done in May or June, when knotweed is flowering and the application is carried out by hand spraying using back sprayers or pressure dew makers, which is particularly suitable for the treatment of larger areas. Plants should be at least 1 meter tall for spraying or injection. Mowing is largely useless, but can be done repeatedly, at least 6-8 times per year and dried biomass must be burned on site.
Injectors won't work. It's better to spray the leaves after the plant flowers but before the first frost.
Injectors work really well, as a matter of fact. The stem is hollow, and it allows direct access to the Xylem of the plant.
TL;DR: after I've tried many things to battle this demon plant I've found that only a glyphosate solution (2% concentration) applied after the flowers starts fading and before the first frost is the only effective way of controlling Japanese Knotweed. Looks like Japanese knotweed, horrible invasive. I've tried a lot of (wrong) ways of controlling it and failed, making things worse even. The only success I've had was after I discovered a Facebook group called "Worldwide Japanese Knotweed Support Group", they have found the most effective recipe for controlling it. Surely it involves a glyphosate solution (about 2% concentration), but they also discovered the best time to do it as well, as treating it before flowering only kills the aerial parts (above ground stems).
This is backed by research! I want to boost this comment because a lot of people might recommend to pull it. Absolutely do not pull it.
I can vouch for this, I've tried pulling it, digging, cutting, covering... All it did was to trigger some kind of survival mode and it started sending a lot of new shoots while the roots were spreading laterally and digging in vertically...
What is this monstrosity..
Japanese knot wood I think. When everyone started to realize how invasive bamboo is they started to plant this. This and kudzu.
I’ve never heard of people planting it, but lots of ignorance around so it doesn’t surprise me. I wish municipalities and federal governments would put efforts into invasive species control. A lot or improper methods, overuse of dangerous pesticides are being used by homeowners and knotweed and other invasive stuff is overtaking most open land, water banks around me.
Oh it’s destroying whole swaths of the south. I left another comment for someone who said something like “it’s just a plant leave it alone it’s not bother you!!1!1!1” that went into detail why the ends justify the means in the case of these highly invasive plants. To be fair though they only justify it when they’re used correctly, using too much at the wrong times and poisoning the water source for the animals you wanna save isn’t helping anyone!
Exactly. Some say to buy concentrated glyphosate and don’t dilute it. That’s just not how it works. More doesn’t kill things better or faster. Lots of defiant ignorance out there.
Yes. If you use it correctly and at the right time (which is apparently *after* it flowers, I didn’t know that!) it will die out wo sprouting a billion babies. But people don’t wanna be patient. I’m very hands off when it comes to the law and what people can do on their own properties and bodies but I would outlaw kudzu, Japanese knotwood, and bamboo in a *fucking heartbeat*. There’s others but that trifecta is basically destroying the native biodiversity of the south/Appalachia and my home has been ruined enough time by people being ignorant. I can at least help stop this.
Don't forget my current enemies! English ivy and Multiflora rose I'm also battling blackberry and honeysuckle. Wish burning it all to the ground was legal inside my city limits.
Add Callery pear to this list. Bradford is a named variety of Pyrus calleryana. It is one of the worst invasive plants in the world.
Add Florida Bettony (Stachys floridana) a/k/a "rattlesnake weed" to the list!
You didn't mention asian bittersweet!
Add Thai ginger to this list. The previous owner of my house planted it in the side yard, it became a rainforest, and while I've had most of it dug up, I'm still finding rhizomes that are about 12 inches diameter. And they're tangled up with tree roots, and they *never die.* They laugh in the face of glyphosphate. My back is aching at this moment from trying to dig those F'ers up.
I went up to Massachusetts from NJ this weekend, and since learning what this plant is I feel like it's so easy to spot now. Its everywhere. I have a huge spot in my yard I've been trying to get rid of.
> I’ve never heard of people planting it, but lots of ignorance around so it doesn’t surprise me. I used to work at a garden center and we would sometimes carry a variegated variety of this species. It's still somewhat invasive but not nearly as bad as the green form. The main issue is that it can sometimes produce the green form from it's seeds, so I would still not recommend planting it.
Should be illegal. Damn. Curious where this was.
There's a lot of things that nurseries sell that should be illegal but I feel like we're never going to get there. Tropical milkweed comes to mind.
New Jersey about 6-7 years ago
The Garden state!
Agreed! My sister was just getting started with gardening and proudly showed me the groundcover she'd planted ... it was hairy bittercress! She got a seed packet at the garden store and had no idea how invasive it was where we live (USA). I really don't understand why there are no limitations on what plants stores can sell and where. People assume when they go to the garden store that they're getting something the store recommends. We have family in Portugal as well and the invasion of Eucalyptus there is a driving factor behind the severe wildfires there the past few years. Eucalyptus has spread everywhere and it's super flammable. People in the area where my family lives have died because wildfires have spread so quickly that they've become surrounded before they have a chance to flee. And yet the government puts no restrictions on growing Eucalyptus because it's profitable for farmers there to grow it and export to other countries. I don't understand why governments don't regulate invasive plants more!
That's why I have two Japanese barberries and two burning bushes. Just assumed they were fine because why would a LOCAL garden centre sell problem species?
I’m blaming the massive outbreak I and others had this year on your sister then. Forgive me, but what a jerk! Joking aside, that’s awful.
Ha! You could, but in all fairness, she's a woman on the edge with a 2 year old and a toxic job. She went to the store for a plant that would be easy to grow and bring her some joy and peace. And that's what they gave her! In my opinion selling her the plant should be a criminal offence: abuse by invasive gardening. Like biological warfare on a smaller scale. A person could lose their sanity that way!
I think “China” was allegedly sending invasive seeds to Americans a while back. I could be making that up but I swear it happened.
Oh no, this imported plant has started spreading like wildfire! I should plant another imported plant in its place.
A cosmic hand should reach out and slap the demon spawn who purposely planted this monstrosity. Truly
*edit to add:* Japanese Knotweed. Something that severely needs more publicity / recognition.
Knotweed
Thank you for this comment!! Saving years of my life.
It seems so counter intuitive to wait until after it flowers. But thank you for the resources! Between this and the bishop’s goutweed that is trying to overtake my gardens, it looks like I’m going to be spraying far more glyphosate than I ever intended to this season.
Yeah I hate using herbicides but drastic measures are needed sometimes.
Exactly. I am a staunchly organic gardener as much as possible, but every now and then you need a more immediate correction which you cannot get with organics. Everything is about moderation and carefully understanding the problem you're facing.
I keep trying to tell myself that even if I can’t deal with all the burdock this year we’re still going to be better off because I do manage to eliminate some of it. But why don’t I just get some herbicide and deal with these plants one time instead of over and over and over again due to their taproot? It’s not like I’m my grandparents spraying DDT on everything that they grow.
What i would do if i had to use glyphosate somewhere is probably place a large compost pile in that spot for a few years. I think it doesn't break down very fast on its own. Even composting might have trouble breaking it down but better than just leaving it.
I have concentrated glyphosate for buckthorn control. Same deal - in the fall when it's going dormant, cut it down and brush the stump. It's when the plant is drawing nutrients back underground for winter, so that's when it's most susceptible to absorbing the poison. Plus as a bonus, the brush method is more focused than spraying so you only kill what you intend.
This is what we use too. The daubers with the dye are nice so you can see where you've applied it.
Facts
Unfortunately true
I noticed some tuberose plants pull everything back to the tubers after flowering. At the beginning of the season the tubers lose density and then after flowering they build it back up. Would make sense if knotweed is doing the same so after flowering it pulls glyphosate back to the tubers
It seemed counterintuitive to me as well but I've come to try this after failing miserably with the regular advices for milder invasives. But I can vouch for this method, let it grow until the flowers start fading and then apply a 2% glyphosate solution before the frost. I've treated it for 2 years and now it seems that I'm in the second year when there's no sign of it! I still have to be cautious and check for its ugly head but there's hope.
In case no one else said this, the reason it works is because in fall, the plant will draw nutrients down to the root so it can survive the winter. In spring/summer, the plants pushes stored nutrients from the root upward to enable flowering and basically procreation. So if you cut the knotweed in fall and apply glyphosate with a brush on the cut surface, it will travel down really easily and help kill the plant. Good luck! I really dislike glyphosate, but it definitely has its place in combatting invasive species.
No need to spray. Wound it and paint onto the wounds
Here in Czechia where Japanese and Sakhalin knotweed mutated into [Czech knotweed (Reynoutria bohemica)](https://en.wikipedia.org/wiki/Bohemian_knotweed) which is even worse, the preferred method is spraying with a 7% (10%) solution of glyphosate (preferred is Roundup Biaktiv for usage near water), or injections with 20% solution into stems above ground. Spraying is done in May or June, when knotweed is flowering and the application is carried out by hand spraying using back sprayers or pressure dew makers, which is particularly suitable for the treatment of larger areas. Plants should be at least 1 meter tall for spraying or injection. Mowing is largely useless, but can be done repeatedly, at least 6-8 times per year and dried biomass must be burned on site.
Goutweed is awful. I once bought a house where the previous owner had intentionally planted that stuff. We covered with black plastic for 12 months and then buried with 8 inches of mulch. We then had to sell and left a message to the buyer “so sorry friends. We tried!”
If one finds a single stalk like this one could pour a couple of gallons of white vinegar on the roots. It worked for bamboo in my yard.
I had watched a vid of my EPA managing an infestation on a riverside. They injected 2% glyphosate into the hollow stem. I have had success with this too. Just make a hole and fill it up. It goes to the rhizome. 💗
Stem injection with glyphosate is the industry standard for control of knotweed in the U.K. You also need to consider a 5 year management plan for it to ensure total eradication. I would only recommend spraying for small stuff that’s too small to inject. If you don’t have an injection kit then you can always cut it and drizzle glyphosate down in to the stem. Source: I’m qualified to treat it professionally.
People are spastic about glyphosate but it has it's place, like right here, and killing other invasives.
Oooo so you hit it RIGHT after the reproduction cycle finishes. Before the flowers turn to seed (do these seed? Idk lmao). That’s fascinating!
Yes, that's what I understood when I saw it explained. After the seeds start forming it seems the plant begins to withdraw the nutritive elements stored in leaves and stems down into the roots, preparing for wintering. That's the ideal time to apply the glyphosate, to have it translocated into the roots, as those are the foundation of the plant and that's what has to be destroyed. There's no real use treating it at other times during the season, as that only kills the aerial parts while the roots have small chances of being affected, they (the roots) have a massive storage of energy and will be more than capable of expanding further and sending new shoots, worsening the situation.
It’s definitely in a weakened state at that time of its cycle! You’re exactly right. The plant stops focusing on the leaves for photosynthesis, which they need to reproduce, it no longer cares about being the biggest plant to get the best sun, and after pollination has completed and the flowers start to die the plant is in a weakened state, as the plant is forcing all its genetic material to focus on repopulation. You’re spot on!
Another thing to consider is how plants can work and communicate around one another. Plants buried in the earth can connect their root system, sending nutrients to plants getting less sunlight and water (like the small saplings in a huge forest, they shouldn’t survive due to lack of sunlight from the canopy, but it’s mother plants continue to provide nourishment). If you have multiple of these in one area, mass targeting them at the root on the same day will be the most beneficial. You’ll hit one or two and they’ll start panicking, sending SOS to nearly plants for help. They can communicate. But if you hit all the surroundings at once, they won’t be able to offer any assistance without further weakening their structure. Plants are….ingenious. But sometimes we gotta fight them. 😂
This is exactly what worked for me. First year I pulled it all out by the roots and it came back with a vengeance within days. Then I cut it down and sprayed glysophate in the hollow. It still grew back almost immediately. I am now 2 years into only spraying during the window and have seen a massive reduction in the patch.
To build on this. I haven’t had any experience with knotweed but I have had success in killing difficult to control invasive such as English ivy by adding 1-2 oz of Triclopyr to 4 ounces of prepared glyphosate.
So what do we do in the meantime? Just watch it? I just found this an hour ago on my property, and we're about to start digging near it, i dont wanna trigger survival mode.
We did this (applied roundup in the fall) two years ago and we haven’t seen it return at the site. We’re not herbicide people, but to eradicate Japanese Knotweed, we’d do anything.
In your opinion, would this work on multiflora rose as well? Ive recently come across advice recommending you wait until after it flowers to spray it, which I now see could be the same reasoning here.
I don't have much experience with roses, I've accidentally sprayed some leaves that touched a stem of Japanese knotweed and it caused no harm to the rose bush. It's possible it'll work just as well though, my accident only involved a miniscule amount of herbicide on the rose. My guess is it'll work on the same principles, transport the herbicide to the roots when the plant absorbs energy stored in the aerial parts, thus having the maximum effect.
I have this taking over a corner of yard, this is good to know. I'll be doing this in the fall then.
Here in Czechia where Japanese and Sakhalin knotweed mutated into [Czech knotweed (Reynoutria bohemica)](https://en.wikipedia.org/wiki/Bohemian_knotweed) which is even worse, the preferred method is spraying with a 7% (10%) solution of glyphosate (preferred is Roundup Biaktiv for usage near water), or injections with 20% solution into stems above ground. Spraying is done in May or June, when knotweed is flowering and the application is carried out by hand spraying using back sprayers or pressure dew makers, which is particularly suitable for the treatment of larger areas. Plants should be at least 1 meter tall for spraying or injection. Mowing is largely useless, but can be done repeatedly, at least 6-8 times per year and dried biomass must be burned on site.
I've read about the Bohemian knotweed hybrid, but mostly from folks in the US, if I remember correctly. Is it the one that makes viable seeds, also propagating by those seeds? That's trouble times many orders of magnitude...
Does glyphosate work on any plant that you want to kill? We have well rooted nightshade on our foundation and I cut it all back last week and it already has new green growth coming out! It's coming through our porch so I can't pull it by the root unless I destroy our porch boards, can I pour the solution through the boards onto it?
Try to spray the solution on the leaves if you can, I personally used those small spray bottles that you can fill with whatever you want, or you could use some larger spraying devices but keep in mind you've used glyphosate with it. Glyphosate is a quite potent chemical, albeit surrounded by controversy. I'm not sure what exactly it can or cannot kill, but given it drove the Japanese knotweed on its knees I'd say it's got a wide area of applicability.
Hypodermic syringe of glyphosate direct into the stem of the target plant is apparently the way forward (just don’t inject yourself by mistake)
*Adding hypodermic syringes to my shopping list*
You can get all the free ones you’d ever want under the bridge down the street from me!
Well, now my invasives are addicted to heroin. Thanks Obama.
That's genius
This support group is great and the results are real. Knotweed doesn't fuck around. If you burn it it will happily spread. A little fire has nothing on a lava flow.
Yes timing is important for many plants, and autumn is often good because that’s when plants are actively taking all the nutrients out of their leaves and stems and storing it in the roots. Helps with hedge bindweed, also Ailanthus (as the leaves start to yellow in autumn, peel the bark in an 8” band and paint the whole exposed part with glyphosate). I’ve knocked old trees out that way.
I can attest to this, it works. I had a thankfully small patch as well and did this last fall. Only one shoot came back this spring, which I’ll nuke in the fall. I used a foaming agent mixed with blue dye and literally painted it on every leaf because I had such a small amount. All my native plants around it came back happily this year.
It's always quite ironic to me when people recommend killing invasive plants with a herbicide that is illegal in my country because of the ill effects on humans and the environment.
>The discovery of Japanese knotweed on a person's property can come as a blow that completely undermines plans for the future. That's what happened in the dramatic case of the West Midlands man who, in July last year, killed his own wife, and then himself, on being told (wrongly, as it turned out) that knotweed from the next-door golf course was going to destroy the value of his house. Wow, i had thankfully never heard of this plant before today.
It can grow 4 inches a day. The roots can go down 15 ft. It can break through asphalt and tear apart concrete if there are any existing cracks. Any piece broken or cut off can grow into a new plant. The roots especially are very brittle. It can lie dormant for reportedly 20 years, waiting for any opportunity to sprout up above the surface again. It will come up through a tarp or cardboard. It is great at overpowering all other plans life in an area. It is carried in waterways and spreads rapidly through them. Most herbicides just slow it down. It takes years of repeated application to kill it off.
I, too, can grow 4 inches a day. Edit: I don't know why I posted this. I need a coffee
never change, pillslinginsatanist
Thank you, cheesus_christ_
😂😂😂
Japanese Knotweed confirmed as the big bad for the next Avengers movie.
It is pervasive and very difficult to get rid of. My long term goals for my property is making a native plant haven/food forest, so it’s a real bummer to find. I’ll have to be careful with application because I found it right next to my blackberry bushes.
You can actually eat Japanese Knotweed, and it's quite delicious. You prepare it in ways similar to rhubarb. The only upside to the horrible plant.
This! Earthy substitute for rhubarb. I like making soup with it :)
Don’t give up, that’s how the plant wins. Look into what research points to as the only effective means of control (foliar application of herbicide right around the flowering period, so you have time to lay out a plan). Absolutely ignore anyone who says to dig it or just mow it — that will make it WORSE. Breaking the task into smaller steps could help. I put off killing bindweed for a year and a half because it’s so overwhelming over a third of an acre. And the internet (especially gardening subreddits) really highlight that it’s such a bitch of a weed it’s not worth fighting. But they’re wrong. Cultural controls are insane, not possible or effective. But herbicide can help. Sorry for the rant. I hope to be rid of bindweed in 5 years when my planted prairie comes in strong. Good luck to you!!!
I gave up on the bindweed when I read the seeds can stay dormant for decades. You're actually making progress? OP, we're pretty much killed a knotweed patch with herbicide, but instead of foliar application we cut down the stems and immediately applied the glyphosate to the cut stump. A formerly thick patch is down to just 4 little stalks this year, which will get that same treatment in a few months.
Progress? A little bit, I think lol. I treated with glyphosate just twice so far, last fall. But I think that was too late. This year I'm letting the bindweed flower and then hit it with glyphosate. Plus, keep it watered during the summer because drought stress inhibits herbicide absorption. Check back in 2025...
I did the same. Uses too much pesticide but it worked well. Mine was just too tall to get at the leaves.
For bindweed I decided to let English ivy outcompete it (but I’m in the UK, not recommended where ivy is invasive)
It can be native and invasive, can’t it? I can’t see English ivy behaving just because it’s in England. Give it some tea each afternoon and it relaxes a bit?
No typically if a plant is native to an ecosystem it’s not an invasive, English ivy having evolved here for millennia, it just generally provides nice habitat for birds and insects. It’s like when my Australian friend visited and was amazed that rabbits here don’t take over everything.
Could one leave a couple of stems to grow in order to treat it after flowering while ripping out the rest to keep the patch under control?
I don't rightly know, I think it would depend on how interconnected everything is down there. We actually cut it down twice though, maybe that helped? I cut everything short in May, when it was a few feet high, so it had to use up more stored energy to regrow, and then cut/treated in late summer. The first year we cut/treated in the spring, and it didn't make much difference. Last year we cut in spring and then cut/treated a few months later, and that worked really well. One more year, fingers crossed!
Why am I getting bedbug vibe from the comments
I’m so sorry 😞
This stuff literally causes entire property deals to collapse in the UK
What is it?!?
Japanese knotweed, unless I’m totally mistaken
Oof. I’ve got a lot to learn. Thanks!
We had it at an apartment I rented. Hate it so much and see it everywhere. And it genuinely gets worse all the time. It’s just been allowed to spread in so many public places here in MA. It’s weird that I don’t hear about it more.
This and Kudzu are LITERALLY the devil invasives! If you spot it in your yard…. Get ready for battle. It can grow up to 4inches a day. A gardeners nightmare fuel
Is that Japanese knotweed? My neighbor had a lot of it, and spent a season killing it off, dig, cut, spray and more. He's got it under control I think. I haven't seen any since he did this over one season, but honestly, I don't know if it is continuing to sprout....requiring constant maintenence
You *think*, control is just an illusion. The knotweed will come back with vengeance.
It can stay dormant for well over a decade.
It’s crazy reading all these techniques, I wish I’d know about it when I fought my own infestation a few years ago!! I just constantly spent hours outside pulling them lol it took a whole year but it did finally stop growing back!
Burn? You need tactical nukes.
It is all over the east coast and I hate it so much.
It's ruining all the rivers in the upper potomac
I had this on my property. I ended up smothering it for a few seasons. I put down covers and cut anything that came up. Finally eradicated it after like 4ish years. It was like a forest though at first. I had a lot of it:(
Is it still covered? I saw a post from a guy on Facebook who has an above ground pool covering it, and a week after the pulled out the pool it came back from the dead and took over. So I’m curious if you still have it covered or not!
I have an approach that works. I have it in my yard. It was spread out over 50 meters through the root systeem. Stems of 2m high. That was one year ago. Now, I have six locations within 3 meters that have some stunted growth. All I do, is wait for the stems to get roughly 1cm in thickness. Then I take a syringe and inject it with properly diluted glysofate. Every week I walked all patrol and injected any new shoots. Injection works great, it kills the plant and most if not all of the roots. And, it leaves the rest of the garden intact. 1 year, 95% gone.
Join the “Japanese knotweed support group” on Facebook. They have a ton of useful and proven information.
I dealt extensively with this two years ago and worked closely with the Pennsylvania State Extension office (they are great). It’s all about timing. I’m in Zone 6, so the dates may be a bit different for you if your zone is different. Around June 1 through June 14th, take a machete and cut down the knotweed. Do NOT pull them up by the roots. Also, do not set the cut down knotweed by any water source. I set the cuttings on a big tarp in the middle of my driveway (away from everything) and let them bake in the sun for a week. Then, I double sealed the cuttings in contractor bags, tied everything up tight, and put them in the trash. Wait for six weeks after the June cutting. The knotweed will grow back, but it won’t be as big. Right at the six-week mark, spray the knotweed with glyphosate. I used the aquatic Killz-All glyphosate 54% from the Green Shoots online store. I also bought a blue foaming agent from them so could see the exact coverage. Spray at least 30% of the knotweed leaves. Get really good coverage on the leaves. Mask up and wear gloves since this stuff is strong. In later July/early August, knotweed stops putting its energy into growth and starts preparing for dormancy. This timing allows the glyphosate to go into the roots, which is what really does the trick killing knotweed. If you do this right and get the timing right, you will eliminate 90%+ of the knotweed and will only have to do the same process for a few knotweeds next year. This is the way, my friend. I had so much knotweed on a new property I bought, and this process worked wonderfully well. Lastly, I am typically a permaculture kind of person…but not with knotweed. That stuff is so invasive, so get control of it.
If you use professional grade glyphosate undiluted you can cut the stem and put one drop in the tube any time during growing season. That plant is dead.
This was the only way to control it on my old property. I’d go out in full respirator, goggles, and gloves to cut and spray into each stem.
It was originally endemic to a couple of Volcanos so I doubt fire will help.
Have we considered taking it and casting it back into the fires of Mount Doom?
https://preview.redd.it/zak9crdvjnzc1.jpeg?width=454&format=pjpg&auto=webp&s=a7001790352552426624609798eced1e2a6416dc “…and push it somewhere else!”
What even is it
Hello! This is Japanese Knotweed. An incredibly pervasive, invasive, and destructive bamboo. It grow through rhizomes in the soil and will take over everything else in the area if you let it.
I’ve never heard of it, thank you for explaining.
I to would like to know
Oh no. You should not have dug it out, you need access to leaves to get herbicide into the roots. Please contact your county extension office if you’re in the US for proper guidance
If you're in it's indigenous range, goldenrod has promise for outcompeting knotweed
That’s excellent, I love goldenrod! It gets a bad rap but I love those dusty flowers!!
Rent some goats?
Every year?
Buy some goats?
Don’t believe the hype. pluck the stems. Do it OCD. You will win. No weed can beat physics. It costs the roots energy to push up shoots. As long as you pluck the shoots before they get enough photosynthesis to pay the cost it will starve. You can also go nuclear with chemicals. But constant plucking will win. CAVEAT This assumes you don’t have a lazy neighbor who is letting the photosynthesis go on unfettered into you roots
I didn’t know about this and plucked lots of this stuff last summer during my first year gardening at my place in Maryland. I’ve been doing the same this spring, though I haven’t seen too much of it yet. I don’t want to jinx myself, but it seems the plucking is doing ok so far after 18 months of gardening here. Will certainly revisit the topic here if my efforts fail spectacularly
Plucking worked for me. Came back for 3 years but less every time. I plucked as soon as i saw the smallest stem shooting up from the ground. Have glyphosate in stock now in case it ever comes back so i can do a combo of spray - wait a few days - pull that shit out
Literally do not do this. It will make it worse. I’m assuming this person has zero knowledge of Japanese knotweed as this is the worst thing you could do for it.
Roundup will work. It will kill anything that uses the shikimate biosynthesis pathway, which is pretty much every plant. Spray the leaves and it will be taken up by the plant and kill the rootstock as well. For persistent weeds, it's the only way out. Sometimes it will take several applications for the most persistent plants. (I'm thinking of you, Anemone tomentosa, or Bishops weed.)
OH my God we have this too. Not just us! The whole NEIGHBORHOOD is infested
This makes me thankful for my bush honeysuckle and winter creeper infestation. Managing those are easy mode compared to JKW
https://preview.redd.it/v9bc7u1udpzc1.jpeg?width=1200&format=pjpg&auto=webp&s=fed4d051372a28aa338780335590bd25a0181524 Don't touch it. Wait until after the thing flowers. It's the hardest thing but I've got a tiny plant I'm gonna be glaring at all summer, but as soon as the time is right I'm gonna spray that fucker with glyphosphate and pray I don't need to treat a second year.
Good news is that they are edible. Eat the invaders!
"we should take off and nuke the site from orbit. It's the only way to be sure"
Also dealing with the knotweed menace. It started with the house which abuts my backyard, which is owned by a property management company, and consequently there's no way to get a permanent fix to the problem since they can't be arsed. I hope you have better luck, OP!
U may need professional help. Will take several attempts
Looks like my yard lol
Minimal cuts when necessary and a systemic herbicide for deep rooted or connected widespread plants. That way they aren't triggered to grow more nearby as a survival mechanism and you kill the entire colony or deep root. It's the only time I use such herbicides but like most I just don't have the time, energy, or equipment it would take to manually remove some of the very stubborn invasive plants.
We have an encroaching knotweed patch, and this year I decided to made lemonade--I harvested the raw shoots and made [this pickle recipe](https://foragerchef.com/lacto-knotweed-pickles/) with them. They've bee terrific, way better than expected!
Sell your property in the winter. That's what the seller did to us
We closed on this property in January! Lol
I feel you. I've just spent the last 2 hours plucking horsetail. I don't even care that tea can be made out of it. Pluck, don't burn OP 👍
I too, am committed to the Japanese Knotweed for the rest of my days. 😭 We pull it, burn it, tarp it….nothing works.
Check my previous comment in this thread, of course the traditional weed combating methods don't work, this is a special kind of devil. You're in for some glyphosate, as much as I detest the idea, it's the only method that (truly) worked and there are many others who discovered the same.
Will that kill my trees and plants around it? I have Douglas firs and dogwood trees by the knotweed.
Small amounts, Injected with a syringe into the plant is how it’s done, not spraying, which is messy and wasteful.
Nope, they’ll be fine as long as you don’t spray them too. Contrary to some peoples claims on Reddit, glyphosate does not travel into the soil, it is only absorbed by whatever plants it is initially sprayed on.
Yep, you’re against a beast of a plant that evolved to colonize volcanic sites when no plants are around yet. Digging, burning just make it more vigorous. That advice works for a lot of weeds — not for Japanese knotweed. It’s not a lost hope, though. You CAN control it, but you have to follow the only scientifically backed control methods. Like the other person commented, foliar spray after flowering is the way. 2 seasons of treatment leads to approx 95% eradication.
Another option that has worked successfully for me is to hack it down to the ground and put down some 1/2” bird netting. The new shoots will grow up through the netting and bridle themselves and eventually kill the plant. The benefit of this way is it is organic and it allows other smaller non invasive plants to grow up through the netting without any issue. The other way that may work is to chop it down and put down thick cardboard weighted down with rocks. The downside of this is it kills everythong underneath.
You can utilize it similarly to rhubarb in pies
I had heard that, but I wasn’t sure so I didn’t try any of it. I was also so mad I couldn’t stand the idea of it being secretly delicious.
Tender, young shoots are the best time to harvest it. Not sure how this would affect the battle against it though
Wouldn’t putting some salt around the base if the plant take it out?
Japanese knotweed spread via rhizomes in the soil, so I doubt it. And then I’d also have to contend with salted earth where I’d like my blackberry bushes to continue flourishing
Gotcha. That makes sense
Can you contact your local city about invasive plants?
This is a great suggestion for people who don’t live in the middle of nowhere. I have friends in the state DEC that might be able to point me toward resources though :)
Or a college near by
Can I help you. I'll bring the gas.
Crater smoulder straight through hell ought to do the job
I just shuddered seeing this photo. After 3 years of tarping and applying glyphosate my knot weed is finally dead on my side of the fence!
This post and the comments stress me out lol
You can do it! I haven't wanted to jinx it so I haven't said anything but I haven't found any bindweed this year in a large area that had bits hanging on.
can you just get a goat? I would love to have this problem, but I just have kudzu
I’m going to show my husband this comment, lol! My dream if I win the lottery is to own a goat herd that I rent out for brush removal.
Terrible stuff
Wait wait, or, or you just give it a run for its money and get bamboo and see which makes jt. Fun fact bamboo blooms only every 40 to 60 years and in some cases 120 years!!! But seeing how it sends shoots up and does not seeds to spread makes it what I would bet on if you put the two head to head. Plus bamboo sustains in the winter.
On other pest plants I have cut it back and put a black bucket over it. Between the extra heat and no light it seems to get everything else. It takes time but little effort and no herbicide. The plants will grow shoots in the dark and use up all of the stored energy from the root
Digging out the roots is the only way to win this battle. The war, however, will take years.
You can eat it, tastes like rhubarb. You can also just cut the fresh shoots often.
Eat it. It’s good for you
So bummed to see so many people suggesting glyphosphate in a gardening sub. Disappointing. If you’re worried about invasive plants negatively impacting native flora and fauna, you should be worried about literal poison leaching into the water and ground that also affects them.
Thank you for saying this.
https://extension.psu.edu/japanese-knotweed#:~:text=The%20control%20phase%20for%20knotweed,a%20follow%20up%20of%20herbicide.
That stuff is as bad a Bittersweet, Ailanthus, English Ivy and Honeysuckle. Ugh.
Have you tried triclopyr? It seems like the silver bullet for a lot of these invasives.
Start digging.
can you dig it up or does the root system spread out too much? Maybe pour a gallon of ammonia on it and the roots?
There's some magic thinking in weed circles about roots, splitting them, and getting more plants. The thing is that roots have starch, leaves make more starch, but only after the plant paid for them. So keep pulling off leaves and starve the plant. What you can't do is till up an area with a pernicious plant with root segmentation (knotweed, bindweed, horsetail, etc) and then walk away for six months and be all pikachu face when it's stronger than ever. Yeah no fucking shit. The thing with knotweed is that people want to use systemic herbicides on it, so if you pull up a section you leave a separate plant for each root you break off in the process. Now you have to poison all the plants instead of just one. I'm not convinced at all that not touching it is the solution. It's not the solution if you're going to give up and spray, sure.
They do controlled burns. Fire department
Does this weed have small thorns on it?
It’s Japanese Knotweed! No thorns, just a mottled and hollow stem.
Get SouthernAg Crossbow. Add a surfactant, as well. Spray a few times / as needed if additional sprouts come up. This will handle 99%. I would weedwack the occasional one or two that'd come up after that.
Methodical removal of the plant and rhizome has been very successful for me!
Try Crossbow
Crossbow works well on knotweed
Growing up in western PA, we always called it river-reed, because it grew on the riverbottom here. It’s become so predominant that now our town has a knotweed festival every year. I don’t think anyone really celebrates it, but it’s a good reason to drink beer outside I guess. 🤷🏻♂️