I had a patch of knotweed about 40' long by 6' wide growing on top of a lower retaining wall, it had reached about 6' tall. I sprayed it in late summer with liquid glyphosate and it completely eradicated it with one application. The large leaves have plenty of surface area for the glyphosate to cover. This simple apprach literally took me about 15 mintes to do. I was fortunate because I was working from an upper retaining wall about 6' above the top of the knotweed, so I was spraying down on top of it. I did this job about 5 years ago, and I continue to check the area annually for any signs of knotweed, so far there are none. The approach shown in the video should be highly effective but would seem to be labor intensive. That said, I appreciate the 2 additional benefits of using this cut stem / foam herbicide method. First, you are exposing yourself to much less herbicide since it is not airborne; Second, you are putting much less herbicide into the environment since it is a highly targeted approach. I use this approach when I need to kill Asiatic bittersweet and other invasive vines as well as Tree of Heaven. So all that said, I would use this method on knotweed if you catch it early and there aren't already hundreds of stems. Moral of the story, keep a close eye on your property (especially wet areas) and catch knotweed early and it is easy to eradicate.
Excellent comments, Chris. The approach outlined in this video are definitely for small infestations. We do have a video for treating large knotweed infestations: ua-cam.com/video/YLo28mHgjH0/v-deo.html . That approach uses a foliar application of foam herbicide (glyphosate). I have found (and other research seems to support) that foliar applications are the most effective. They are just not as precise as you note.
What Spray did you use? Was it just a high concentrate of glyphosate? I have about double that area that covers both sides of a creek bank. Ive been fighting it for 3 years. It grows back faster then I can treat it. I always cut it down then treat it with round up with the Glyphosate. It lasts 3 weeks tops and the crap is growing back.
@@funkdaddyflex Treat in the fall. You will have much better luck. Check out our other video for treating a large patch of knotweed. ua-cam.com/video/YLo28mHgjH0/v-deo.html This video shows how you can do a foam foliar application.
i have been using your product this past season and am happy ro report that although not completely gone has greatly reduced the amount of shoots - the greatest benefit i have found is that i can spot treat so specifically that it doesn’t destroy the lawn around it - using less poisonwith greater results - not to mention much more cost effective
Derek, Thank you so much for the comment! I am going to come out with a video and guidance document on dealing with "straggler" knotweed - i.e., those small knotweed plants that linger after an initial treatment.
Great information here. Thanks for creating this. Battled JKW on the farm, really got out of control before we realized what was happening. I did a lot of the cut/apply method. I found it VERY effective. I've almost got all of it eradicated after 4 years, but I still have to keep an eye out.
Thank you, Eric! It sounds like your treatments have been very effective. What you say about keeping an eye out for it is very important. I think many people think they have the JKW beaten, but it can slowly creep back.
@@ericzipf1332 You may want to skip a year of treatment. The small stems remaining don't have enough surface area to kill the huge root which I guarantee is still surviving underground. Yes, I work for the local county noxious weed department where I am responsible for tracking down knotweed on thirty river miles, by myself, due to not enough grant money from the state to hire more workers. Though I doubt anyone is crazy enough to want to go through what I do in a day or more determined to save one section of a river or more outraged about losing all our rivers. Future generations will not know what river's natural authentic beauty looks like.
@@ericzipf1332 Actually we switched from glyphosate to Imazapyr three years ago, so Imazapyr is what I have had great success with as far as my double spray technique. I didn't mention it because the general public needs to stick with glyphosate. Believe it or not people, glyphosate is the safest herbicide on the market. No matter what you use... if the knotweed is anywhere near water you need a permit from Department of Ecology and a Pesticide Applicator license as well. Better off hiring a company who has the permit, license, knowledge and skill.
Was going out today to cut. Now I can wait til Fall. yeah! I have been successful with the buck thorn. This is a very informative UA-cam and product worked wonders. NO more buck thorn!! Thanks Jim
I am responding to a few of the comments below. First, glyphosate does work well on Japanese knotweed. Swansea University did the most comprehensive research to date on control methods for Japanese knotweed. According to that study: “Greatest control of aboveground F. japonica (Japanese knotweed) growth, defined by reduced basal cover and stem density . . . was obtained using glyphosate alone.” That study also found covering knotweed with plastic membrane the “least effective.” Link: link.springer.com/content/pdf/10.1007%2Fs10530-018-1684-5.pdf . Second, it is critical that a person apply glyphosate with accuracy, especially if there are nearby desirable plants. That is why foam herbicide works so well - you can kill just the non-native plant. Third, yes, I agree 100% that we are losing biodiversity. Japanese knotweed is one of the reasons. In any mature knotweed stand virtually NOTHING ELSE GROWS. If you remove a knotweed stand and plant native plants, that is a huge net positive.
Thank you for producing such an informative, easy to understand video. My neighbor and I both have wells, and also there is a pond about 100 yards downhill from the Japanese Knotweed stand whch is located between our properties. Is the herbicide safe to use in this case?
Mister Drummings - You are most welcome! Fortunately, this herbicide is generally immobile in soils because it binds tightly with them. This greatly reduces the potential for it to infiltrate groundwater. Your pond is also a good distance away from the application site. Assuming there is vegetation between the knotweed patch and the pond and assuming no literal "gully washer" the day of your application, you should be fine. I also try to be extra safe and apply when rain isn't forecast for two days or more.
Hey, first, I really appreciate your videos. I have learned a lot already. Do you still suggest this method? I have watched your most recent video for homeowners and noticed that you don't mention this method. As a general contractor, I'm looking to assist some clients with some small ish patches. We want to remove the plant material regardless, so it makes sense to be to follow this method where we'll cut the plants (after flowering and before frost), then apply a foaming herbicide to the cut stem tops.
Timely question! The method described in this video is easy for homeowners, and it allows immediate removal of the tall knotweed shoots from sight (a concern for many homeowners), BUT it is not as effective as other methods. I am going to revamp our guidance this winter to offer more treatment methods at different times of the year. While I still believe late fall after flowering but before frost) in a typical year is the best time to apply, it may not always be. Moreover, many homeowners are overwhelmed with large knotweed plots and can’t hire professional help. These people need a solution that allows them to start work on the knotweed plot earlier in the year. So, you’ll see more videos from Green Shoots soon!
Thank you, just ordered your foam product! So we have this behind our garage, moved to this house two years ago and I didn’t think much of it until I finally decided to research what this plant is. So now that spring time is coming should I start using the glyphosate on the shoots once they begin to spout? Or should I wait till fall after the plant is done flowering? Thanks again for making this video and getting the information out there!
You are most welcome! I would wait until fall to do your treatments. I know that's a long wait. However, the knotweed plant is putting all its energy into pushing sugars into the foliage. It's hard to fight against that current to get herbicide down into the rhizomes.
So very helpful! Thank you 🙏 it’s on my neighbor’s property opposite his fence!!! On my side is my garden , about 5feet from fence. We constantly fight it, effectively… now that I know what it is….going 👉 to look for how to confront that… this will be a people problem not envasive plant 🌱 🤦🏻♀️
Interesting and informative video, thank you. Please note, though, that Swansea University is not in England, it is in Wales. It's like saying Vienna is in Germany. or calling a Canadian American. They are different. Wales is a country in its own right
Did you know that Japanese Knotweed is used to save trees? They are making Japanese Knotweed paper in Europe. Also research Japanese Knotweed Permaculture where it is used as an amazing fertilizer. Check out my 'Japanese Knotweed Garden' video. I was badly mis-sold on this house and garden but Japanese Knotweed has been a miracle plant. Bamboo is far worse. Research Swansea University Wales and how they promote Student Prostitution to our poor children. If they can do that, are they really people you can trust? I think not.
I appreciate all the help offered on this site! You mentioned to let the knotweed grow after mid-summer...does this include all the little shoots that I find in the area where I was digging up roots (before I really knew what I was dealing with!)? And just treat each of those individual shoots in the early fall as well as the larger stands that I can get at? Also, I was given some advice to cut off and discard the flowers when they come out--they said that would at least help diminish one way that they spread. Do you recommend that too? Thank
After midsummer, let all the knotweed grow. Then treat it all in the fall. Just make sure you hit all the stems. You could cut off the blossoms. There isn't much evidence of knotweed spreading by seed, but cutting off the blossoms can't hurt.
Thank you so much for the support! As you know, many of us in other parts of the world look to the university in Swansea for guidance on knotweed. By the way, I will be coming out with a new video on stem wiping. Stem wiping more closely uses the same route of herbicide uptake as foliar applications which are very effective in killing knotweed. All the best!
@green shoots Thank you for your video. I have giant knotweed along a creek in my backyard. I know complete eradication is impossible, but I would like to control it in my section of the creek, restore it with native plants & help control erosion. I am using the cut & foam herbicide method so it won't get in the water. I don't know that I will get to all of it this year, is it ok to do it over many seasons? Also the parks department recommended I immediately plant fast growing trees to try to shade new growth out. Do you recommend that? Or wait to the spring? Do you have recommendations for what type of tree would be good for the creek bank to prevent erosion but could also shade out the knotweed growth? Most of the the other things growing in the area are also woody invasives, but there are a few blaack walnut trees. I am in NE Ohio zone 6. Thanks for your help. I know it will take years...
Alysia, yes, you can definitely do the work over a period of years. Just move from the periphery into the center and treat the stuff nearest the shore. If you can get another treatment in before the beginning of winter, that would be optimal. Yes, I think your Parks Department made a good recommendation to plant native trees. In one area we restored, volunteers planted river birch. They are beautiful trees, grow peand have done a great job of keeping down the knotweed. Ideally, plant the trees at least some distance from treated knotweed 5-10 feet perhaps. The black walnuts may themselves inhibit the growth of knotweed and any other natives you plant.
Thank you for this video. It is just the beginning of summer here in New England. As of right now, I'm trying to uproot any shoots that are loose enough. I will do the application in the Fall. One question, though: Once the weed dries inside the plastic bag, how do I dispose of it? trash? Compost? I have some shoots from last season that are dry and I would love to know how to dispose of them safely. Thanks.
After about 2-3 months in a bag, the rhizomes and shoots should be dead. Therefore, you should be able to compost them. You should monitor the pile. I wouldn't spread the material around. One study from England found that desiccating plants for 38 days resulted in no regrowth. Lawson et al 2021. However, that was under laboratory circumstances so I would do the drying for a little longer.
Im going to buy your product and try it this fall! In the meantime what can be done? Ive been pulling it, putting it in thick contractor bags and garbage cans with lids until it dies clmpletely next season. Then Ive been throwing a bunch of roundup on it and covering it with thick tarps to smother. Recently bought a new house last year, and my neighbors yard is infested with it and they do nothing about it ! Ruined my attempts at a garden last year.
My recommended option in the spring is to dig out the knotweed. See Link below. I would not put a tarp on it. It seems that just causes the knotweed to go dormant. I also would not apply herbicide right now. The herbicide will not translocate to the underground rhizome. This video ("3 Simple Steps) is a bit out of date. Check out our newest one - also below. Good luck! Control Knotweed by Excavating or Digging Crowns ua-cam.com/video/k7WgGRiodIc/v-deo.htmlsi=4v5frUOC7vwj6qOY Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html
I treated my knotweed last year the same way as you have showed in the vdeo. This year i have very little regrowth. My question is how do you know when you its 100% dead. I am planning to build over the infected site and would like peace of mind
That's great to hear! I recommend digging up the remaining plants that are still alive. Now that you have killed most of the stand, this should be quite a bit easier.
There's a good article from May 8, 2019, in Slate that discusses the problem with knotweed. It quotes Robert Naczi, a curator of North American botany at the New York Botanical Garden": The biggest problem with knotweed, Naczi explained, is that it grows so thickly there is no room for anything else. “I don’t want to ascribe moral agency to the plant,” he says. “It’s not an evil plant. It’s doing what a plant does. But Japanese knotweed is a very serious invasive. A very, very problematic species. One of the worst invasive species in Northeastern North America.” Here's the link to the article: slate.com/technology/2019/05/japanese-knotweed-invasive-plants.html?.
Thanks for all your extremely helpful information. We have a huge stand of Japanese Knotweed in our backyard and did the initial application of your blue foam glyphosate in two applications last fall (we are in Maine). We had great success and this spring have been removing, and carting away, all the dead canes. With all the crowns now exposed, we can see where knotweed is growing back and so are embarking on digging up as many crowns as possible. My question is: Are there any plants we can plant in this space over the summer that can fill in the area--hold their own with any sprouting knotweed--that could serve as foundational plants as we slowly transform this large space into a flower garden? We realize this will take "a while" but would like to start cultivating some non-knotweed plants along the way.
AH - That's great to hear! That is a very good idea to get something in there soon so that any surviving knotweed has competition. For temporary, natural covers, many landscapers, etc., use an annual ryegrass. That is one possibility. Just buy it from a good source so the ryegrass doesn't have weed seed in it. Mow it before it sets seed. You might also consider planting some of your garden perennials in areas that are pretty clear of knotweed. If you decide to plant native prairie plants, they will compete really well. Trees or tall plants that provide maximum shade would provide the best competition over the long term, but only if that's what you want at the site.
Canada goldenrod is by far the most aggressive and persistent native plant in my opinion (and is very ecologically beneficial). If there is any plant that can compete with an invasive, that would be it. A few other ideas would be yarrow (preferably the wild type), native asters, woodland sunflowers, and/or milkweed (common milkweed, Asclepias syriaca, might be a good bet)
Great video! I have some of this growing in my backyard in Vermont. When we cut the shutes and apply herbicide foam, do we do that once a year for multiple years or should I apply it for multiple days consecutively? And then burn the cut shutes?
Thank you! You should apply the foam herbicide to the cut stems in the fall. Apply it to every knotweed stem you can find. You can certainly burn the cut stems or pile them up. Since you will be doing this in the fall, it's much less likely they will re-root. The next spring you will have some re-sprouts. You can dig those up and apply foam herbicide again the fall to anything that is left.
Hi, thanks so much for all the precious information. We have two big patches on both side of our house. We will start a treatment in the Fall. In the meantime, we are wondering if there are any State resources that you are aware of to help people deal with such thing, or any private companies. We are in Chittenden county, Vermont.
It is generally pretty difficult to get financial assistance for invasive removal work done on private property. Some localities have tool sharing programs or small grants. Many private companies do invasive plant removal, although in many cases they typically do work on a large scale. Make sure you hire someone who has experience doing knotweed removal.
Getting ready to try this in a few weeks. Some of it is coming up through the lawn, I’m a little worried about killing grass if I cut it really low and try to dab the foam on right down by the ground. Is there another method for a situation like that?
That method you just described works quite. You might also cut the grass around the knotweed stem. Only if you hit the green part of the grass will you kill it.
Hello , so glad i found your video - have been actively researching JKW ever since we identified it on our property. We live in New England and it's still spring here - the weeds are already 3 ft tall - if we cut and foam treat them now and then again treat shoots in Fall ( before frost ) - will that impact the effectiveness vs only treating them once before the Fall ?
I wouldn't bother treating now with herbicide. If you do anything at this time of year, I would recommend digging up the crowns. I know this can be arduous, but it's probably the best way to slow the knotweed down at this time. If you do dig up the knotweed, be very careful with the dug up rhizomes. You don't want them to re-sprout. Put them in a black plastic bag and set them in the sun to "cook them." Don't dig near a waterway. At the end of our other video, you can see how to dig up the crowns: Control a Large Stand of Japanese Knotweed in 4 Phases: ua-cam.com/video/YLo28mHgjH0/v-deo.html . Don't feel you have to dig up all the rhizomes. Just attack as many as you can and then treat in the fall.
There is controversy about whether cutting helps or causes the stand spread out more. If you do cut, be sure to be careful with the cut stems. Store them where they won't re-sprout. I personally think digging works better as noted above.
Keep Concentrated or dilute per directions? Can you clarify if I use the KILLZALL super concentrate straight from the bottle or dilute 5 tbs per gallon ?
Good question. Sorry for the late response. Did you take a look at our more recent video on direct application to the knotweed stems? The techniques described work better than the cut stem method: Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html
My husband and I purchased a house last year in the winter and shortly after the snow melted discovered we had a knotweed infestation. We have a small stream that runs behind our house that the knotweed seems to be quite attached to. This year it has started encroaching further into our yard toward the driveway. In my frustration i chopped a bunch of the stalks down as close to the ground as possible and plan on burning it once it dries out. I wish i had seen this video before making the effort haha What do you recommend to keep it from coming further into the yard while it grows before a fall herbicide application? Im afraid if we do nothing it will keep coming closer to the house and become even more of a headache.
In the Spring I recommend digging out the knotweed crowns. View our video on this: Control Knotweed by Excavating or Digging Crowns ua-cam.com/video/k7WgGRiodIc/v-deo.htmlsi=4v5frUOC7vwj6qOY. Also, view our blog post which has the latest resources we offer on dealing with knotweed. greenshootsnews.blog/2024/04/25/invasive-knotweed-green-shoots-has-new-products-and-resources-for-dealing-with-it/
what is the best way to Dispose of all the knotweed plants once you've cut/poisoned the stems? I just used your product to poison about a 40x10 foot section but now have a pile of plants. (I originally was planning on cutting each stem and poisoning but after several hours and only making it through about 1/5th of the patch I decided to go with applying the foam to the plant itself and leaving it). and will the dead stalks from the winter season be able to reproduce? thanks in advance for your help
No the dead stalks will not be able to reproduce. You should be just fine leaving them in place on the ground. We are experimenting with some other methods that will be faster than cutting and treating. However, it sounds like you made it through the full patch!
i have tons of this stuff, what a battle.. the dry stuff in the spring goes up like gasoline, all started cause of previous owner thought a 'bamboo' hedge looked nice..grrr!
Thanks, I been looking for help like this. I have close to 1/3-1/2 of an acre of this nightmare. I live close to a river in Connecticut so should I get the Aquatic Precision Foam or the other.
You are welcome! Yes, you should get the aquatic herbicide if you are treating any knotweed that is right along the water. I would treat those stems immediately along the shore with the cut stump method just to avoid spraying anything into the water. (Or, dig the stems out.) Also, when you apply to knotweed that's within about 8 feet of the shoreline, spray toward the shore. Check Connecticut law regarding aquatic applications of herbicides. Some states require a licensed applicator. Good luck!
I'm developing a plan to manage the Japanese knotweed on my property. I have a few questions. 1. It is late May now, should I refrain from dealing with the knotweed in any way until fall? (Edit: I just saw your response to a similar question below) 2. Would there be any benefit to combining your method with covers/tarps to prohibit photosynthesis? Or is this unnecessary and/or ineffective?
Question 1: I think digging works best early in the year because you are removing the most amount of viable knotweed tissue. It then forces dormant buds to grow which you can treat in the fall. Question 2: covering can as you mention inhibit photosynthesis but it can also induce dormancy. Dormant knotweed can reportedly survive for years. If you do cover it, I would uncover it in early to mid-summer so that you have enough foliage to treat in the fall. Good luck!
May is not a good time to treat - too early. Check out our newer videos such as: Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html Also, if you want to do something early in the year look at: Control Knotweed by Excavating or Digging Crowns ua-cam.com/video/k7WgGRiodIc/v-deo.htmlsi=4v5frUOC7vwj6qOY
I have a decently sized patch growing in the sidewalk next to my house. Should I do the treatment before the fall and then again in the fall? Should I wait until the fall to do anything? Should I cut the stalks down and then do the full treatment in the fall? I'm worried about it spreading into my yard.
Given your circumstances, I would recommend leaving it alone until fall. Anything you do now might encourage spreading. Just monitor your yard to make sure you don't see young plants. If you do, take them out with a traditional dandelion digger or other similar implement.
Hi John, very good informative video(s)! I also saw a couple of videos on extinction of weed with electricity. Seems to be mostly used in UK and to some extent in trials in Germany. The idea being to electrocute the plant down to the root with high voltage. What do you think of this "weed zapping" method? Also glyphosate is mostly banned for private use here in Germany. Roundup, e.g., is available only with Pelargon Acid. Do you happen to know, if this is as effective as glyphosate? Thanks! Markus
Sorry, another question: Some herbizide producer recommend cutting off the plant and then applying it to the inside after scratching the cell tissue. They recommend using a pipette. Bit laborsome, but would this work?
Thank you, Markus! I have followed the weed zapping methods fairly closely. However, I haven't seen any studies where it has been used. I have not been able to see a demo of it yet. It would be fantastic to have another method for killing invasive knotweed. As to glyphosate with pelargonic acid - this is likely not a helpful addition. One study found that with foliar applications to various weeds, "longer-term control and control of regrowth was either not affected or reduced by the addition of PA" (pelargonic acid). Wehtje et al 2009. The likely problem is that pelargonic acid destroys the vascular system in foliage before all the glyphosate is translocated. Do applications of a concentrated mix of glyphosate and pelargonic acid to the stems as we suggest in our UA-cam video: Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html I have noticed much less harm to vascular tissue when an application of a "hot mix" is done to the veins or to stems as opposed to leaves.
@@markusgrune6841 This might work. However, I agree with you - it would require a lot of work! Generally, as mentioned in the Notes above for this video, I now discourage doing cut stem treatments with knotweed. I would advocate instead a direct application of a concentrated herbicide to the exterior stem tissue. Or, you could do injections. Or, if you have a bigger patch, do foliar applications.
Wow, thank you so much for the extensive advice! If I happen to buy a weed zapper, I will record the process and the results and share it with the community here! Cheers! Markus
Spent 5 hours pulling the knot weed out by the roots, guess I didn't get some of the roots and it's growing back strong. Hope this works, flamethrower and kerosene method is the last resort.
Hello, we have a BIG patch of JKW, at least 50m2,growing on our neighbors lot, it's a close as 1-2m from our fence. It's been there for +10 years and had been covered in tarpes about 10 years ago but has started growing again. It was in a shaded area but we didn't know and started cutting trees and bushes last year before we noticed it. The JKW got exponentially bigger and thicker this year because of the light exposure. We can't treat it because it's not on our land. Would you recommend digging in a root barrier and maybe excavating our property? I going crazy standing around doing nothing waiting for it to pop up in our garden. We're trying to create some shade again in the meantime.
Just check out how to eat the stuff. There are videos. It's the most concentrated source of resveratol. East Asians use it for food and medicine. The spring shoots are edible.
If you have no knotweed on your property, a well constructed root barrier could prevent the knotweed from entering your property. Some sources say knotweed rhizomes go down as far as 2 meters or about 6 feet. That's probably unusual. However, you'll want to put the barrier down pretty deep. I know there are article available on root barriers - one from Wagar and Barker 1993. If you do any excavation, be very careful. The rhizome fragments can easily reroot. Keep the excavated soil in that same location.
Hello, I have few patches of knotweed around my property. One patch 30 ft x 30 ft is located on a rocky hill, no matter how long I let them grow the stems don’t get thicker, on average they are 1/8-1/4 of an inch and they are just dispersed through the area. Would cut the stem and treat work for such a thin steam or should I use foliage application? Thank you
Generally a foliage application is more effective. A cut stem application to knotweed is the most precise. If you wipe foam herbicide on the leaves and stems (covering about 30% of the plant), the application will be effective and quite precise.
Thanks for the video! Sorry if this is a dumb question, but what do I do with the dead seeming, dried out portions of the plant? Is it ok to just pull them up and burn them?
That's a good question! Yes, you can burn them or compost the dried stems. The seeds could be viable, but that is not the typical way that knotweed spreads. Just keep any live stems away from moist conditions.
Hello, I treated large area of Japanese Knotweed (maybe 75' x 75') in the fall of 2022 with arduous cutting, bagging and immediate precise application of your green shoots weed killer and foaming agent into the cut stems. This spring 2023 there is re-growth of the knotweed, some of the shoots are small while others are already thick and tall. I am committed to stay on top of the problem. My next steps are unclear. I am not at the location daily, planning and long drives are required to get to the site. What is the best approach for my next steps this spring to control and eradicate the species? Is covering the area this spring with a black tarp effective - helpful in any way or is it ineffective? Exactly what are the best next steps in the my approach to the knotweed this spring, summer and coming fall? You talk about planing native plants to the area, is this done now, is application of grass seed and effective native plant. I Appreciate your time and response.
Linda, at this point, after having knocked it back, you want to do everything you can to weaken the knotweed patch (the clone). This could include this spring and early summer: digging, cutting, and even covering and then in the fall doing another treatment. Digging out the crowns will be the most effective - but most arduous. If you cut, be sure to cut and then also take a hoe and destroy the winter buds that are at the base of each stem - these are thumbnail size buds that will sprout once the stems are cut. You could then cover some of the most vigorous parts of the patch while you are gone with tarp to slow growth further. Finally, in early mid-summer, let the knotweed grow and treat in the fall. With a patch this large, I recommend people do a foliar application of foam to the knotweed. A foliar application is most effective. Feel free to contact me directly if you have any other questions too!
I've heard injecting the base of the trunk w/ a strong mix of water/glyphosate salts is a good method, using something like a cooking "brine" or "marinade" injector. What are your opinions to this approach?
Peter, yes, that method definitely works. What I don't like about it is that it uses so much herbicide! According to Swansea University, this method uses 15 times more than other methods such as foliar applications. That much glyphosate can potentially affect nearby plants (even though glyphosate binds tightly to soils).
@@GreenShoots Actually, injection or cut and pour down the shoot, contains the herbicide inside the hollow shoot as long as you don't spill. But your right, this type of treatment requires undiluted herbicide. Fine for small clumps but not for large infestations. When I have done cut stem I would cut the stem half way through 3 or 4 nodes up, bend the top of the stem over leaving a part still attached to the stem, ram a thin rod down the shoot to break through the nodes, then I put a few squirts of undiluted herbicide down each hole using a hand sprayer. I figure when you open the nodes with a rod the herbicide goes right down to the root. Foliar application is still the best option and gets the best results. I have had to cut a tunnel through fifty feet of briars just to reach the knotweed. All I could do was bring a spray bottle and lopers with me and all I had access to was the lower stem under all those briars. Knotweed grows in the most unimaginable places. It never fails, when I am going that extra mile to find knotweed, wondering what the Heck am I doing trapped in some Hellish brush hole, ready to give up and turn back... there it is! I hate knotweed with a passion. One thing folks should know is, the first time you spray knotweed is seems overwhelming because of it's height but every year thereafter the clump you spraed will be stunted in growth and require less herbicide to re-treat the following years.
Birds are in abundance where my stand of knotweed is so I would like to approach it with the cut method. You replied to another comment that cut/apply is more precise, but less effective. How would you compare the two methods in terms of effectiveness? Roughly what ratio of treatments can one expect to achieve the same level of effectiveness?
Also, you mention that cutting prior to fall treatment does not affect effectiveness. If I have a stand that is thick with old, dead canes, would it be wise to do a mid-june cutting to make access for fall treatment easier. My plan would be to cut new growth to 2 ft and dead canes to the ground.
I would say roughly a foliar treatment can achieve 80 to 95% effectiveness, same with injection. Cut stem is probably 65 to 80%. I will be publishing a video on knotweed stem wiping with foam herbicide. This method is more precise and the effectiveness seems to be closer to a foliar application.
@@ambahgirl I would definitely try to remove the old canes now. The stand will get really dense by fall. I generally like to bend knotweed stems to create better access if you can, but you can trim too if that helps.
Would you suggest the cut stem method if wildlife is a concern? Or if we can manage to keep most critters away until it dries would that be sufficient? Thank you so much for your wealth of information.
@@ambahgirl I am going to do an upcoming video on stem wiping of herbicide on knotweed. That is a very targeted method of application - similar to cut stem in that way, but it should be more effective than cut stem. Generally, however, you are right - once the herbicide dries, it won't be a big concern for wildlife.
Hi from Pennsylvania! It looks like I will have to do a foliar application because the area is so large. If I tackle this job THIS fall, will it be possible to plant the following spring (with the understanding I will probably have to get in there to spot treat) or will having done a foliar application kinda "salt" the soil?
Your instincts are exactly right! This fall, do the foliar treatments (spaced about 2 weeks apart) as we recommend in our Large Stand of Knotweed video: ua-cam.com/video/YLo28mHgjH0/v-deo.html . In the spring you can (and should!) plant. Trees and shrubs will compete best. But other native plants will also do well once established. Spot treatments will be needed next fall. When you are digging to plant be careful. Isolate any dug up knotweed crowns or green stems. A foliar application uses the least amount of herbicide and yet evidence indicates it works the best.
This fall when you do your treatment, apply foam to all the knotweed stems. Also, i recommend our new video: Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html You will have more success with the foam herbicide wiping technique explained there.
Green shoots...when you say to treat in the fall, what is the time frame you're talking about? I am in Massachusetts and have knotweed coming into my yard from neighbors and an area of woods behind the house. I've been digging up roots where I can all spring and am developing an eagle eye for new shoots poking through which I have been digging up as well. Should I just continue to do that through the summer? And then when in the fall is it best to treat? September-October? Thanks!
Yes, that is a good approach - to dig up the knotweed through about mid-summer. At that point, let the knotweed grow and then apply in the fall. You want to do your application before a killing frost. If you are doing a cut stem treatment as outlined in this video, do the treatment about 2 weeks before any expected frost. Maybe, in mid to late September for you?
I’m getting ready to treat JKW with glyphosate before the first frost I have 2 questions, 1) Should I be adding something to make it stick to the JKW? 2) Should I put a tarp over it after I treat it for the winter?
No, don't put a tarp over the treated area. Our foam herbicide system has a surfactant that helps the foam stick really well. You want something like that to ensure good contact and adhesion. Most glyphosate (except aquatic versions) have some kind of surfactant mixed in.
I have it on the side of my yard near my neighbors fence in upstate NY, I do not have the correct tools to completely remove it from the ground by the roots, so I have been removing it from the bottom of the stem with a large knife, i recently moved all of the cut stems (most around 5-6ft high stems) to the area between mine and my neighbors yard to block off view from my neighbors yard into mine, did I make a mistake by doing so? Will it spread into my neighbors yard? And what are your recommendations on what to do with it all and how to effectively remove it without the correct tools?
Just so I understand - you are cutting off the tops of the knotweed? If so, that can work. Just keep doing it until about midsummer. Then stop and let it grow. You want enough to treat it in the fall. If you don't want to use herbicide, you will have to keep cutting it for several seasons. Just make sure you store the cut stems in a place where they cannot re-root.
@@GreenShoots no I have been cutting them from the bottoms as close to the root as I can get to, the roots are so far in the ground that I cannot pull them out unless the plant is dying, I moved them in between the space next to mine and my neighbors yard so it blocks the two yards from connecting, I’m curious as to if they will re root and begin to grow in my neighbors yard, they are currently laying on there sides after being cut but they are in grass, will they re root where I have them now?
I'm sure there's a comment in here somewhere about it but if there a time and a place for a weed whacking, perhaps in the spring? Or does that just cause it to spread more?
I generally don't recommend repeated mowing as a control method. It requires repeated mowings every year over many years. More importantly, as you mention, it create a risk of spread. If you are in a relatively dry area, you could try it. Just monitor the site. And, if you are near a water body and there is any chance of offsite movement, definitely don't cut knotweed.
Also, should I cut the stems on the go through the summer before applying the herbicide in the Fall to weaken the plant, or should I just wait in the Fall to do anything?
You can cut them but one cutting probably won't do much. I generally recommend people dig out the rhizomes if that's feasible, and then treat in the fall. If your patch is larger, you might consider a foliar application. A foliar application is the most effective but is less precise. The cut stem application is more precise but less effective.
With a large stand of knotweed (170 feet wide) that is 9-12 feet tall, is it best to knock it down and then attempt foliar application or does that break the stalks thereby impeding uptake of glyphosate? We are unsure if we should chop and apply or knock and apply. Any advice appreciated!
If it makes it easier, bend, don't break, then spray. However, it makes it harder to cover every inch of each plant. To tackle a huge patch like you have, (make a few trails first on the inside and also blaze a trail around the perimeter), start inside the clump and spray all the stems first, then start at the back and work your way out spraying the undersides of the leaves. Next, go around the perimeter of the patch, carefully spraying all the leaves around the outer edge. Lastly, open your nozzle to full stream and spray over the top of the patch from all sides. Take heart, next year the knotweed will be stunted and easier to spray. 1)The ultimate date for spraying Knotweed is on or around September 15, after the bees are done pollinating. 2) Use 2 ounces Glyphosate and one ounce of a sticker per gallon. 3) Tighten your nozzle to just more than a mist (depending on distance away from the plant) and cover every inch of each plant, first the stem, then leaves and undersides of leaves too if at all possible. 4) The silver bullet to eradicating knotweed is this... when you are done thoroughly spraying... wait for the herbicide to be totally absorbed/dry and spray it all over again one more time! (2nd spray could be done the next day.) After only having 10 percent eradication of the knotweed clumps I treated year after year (for 10 years)... I finally used the double spray in one day technique and found 90% eradication the following season.
@@knotweedkninja8539 thank you so much for the detailed recommendations. Making this harder is the fact that this stand of knotweed is located atop and astride a steep berm, and contains a morass of old blackberry and knotweed cane underneath it!
@@sarahlebo4746 You will need to cut the blackberry up into little bits with loppers to have clear access to the knotweed. The canes can be crunched down. I love the sound of knotweed crunching. With enough determination you will be able to do it. If nothing else, stand on top of the berm, open the nozzle and spray as far as you can over the top. Sometimes that is all you can do. Hopefully there isn't a creek below. Another option if it is too steep for you to navigate with a backpack sprayer, although very time consuming, is to mix glyphosate with water 50/50, put it in a hand sprayer, cut one stem at a time, 16 inches high, ram a skinny rod down the stalk to break the seal at each node then spray down inside the tube. It is not as effective as far as eradicating but it will make the knotweed shorter next year/easier to spray. I read somewhere this technique can be done up until it freezes. I may try it myself on a patch in a few days.
We moved onto five acres in 2018. It's been a labor of love trying to get the place fixed up to be wildlife friendly. Last obstacle: 2 of our 5 acres is CHOKED OUT with knotweed!!
For an infestation that large, check out our other UA-cam video: Control a Large Stand of Japanese Knotweed in 4 Phases: ua-cam.com/video/YLo28mHgjH0/v-deo.html The method described there will really help you get this infestation under control. Good luck and so glad to hear you are restoring 5 acres!
Any suggestions on disposing of the cut/ dug up parts of knotweed? Right now my brush pile is pretty high with all that I have taken out and I have found that some of it is starting to grow from the pile. Placed it in a barrel last year but it grew from that as well.
Hi Gerard, I've been dealing with eradicating JKW from our farm. I've almost got it all gone. What I have done is keep canes and roots separate. The canes are laid out on black plastic in the sun to dry out. I don't pile them up too deep so there is good air flow to dry. Once they turn brown, they are no longer viable. With any root material, I store that in metal tubs in my barn, in the dark. I try to remove as much dirt as possible to speed drying. Roots take some time to dry out, but they will. Once everything is dry, I usually just burn it all up. As you have discovered, if you just dig this stuff up and make a pile out of it like 'normal' weeds, you'll effectively just move your problem around and then you'll have two spots to deal with. The drying process is a little bit of a nuisance, but it's the only way. I actually try to avoid digging up the roots and disturbing it, I generally use the cut/spray stump method of eradication, but best choice is very site dependent.
i have usually put it in plastic bags and placed those in the sun for several weeks. It takes a while but you will eventually see a white mold growing on it. That means it is pretty dead.
The roots can get really deep and it can be problematic to dig it out. If you miss any root, it'll just come back. There is no one answer that fits all situations. I use both chemical and mechanical means to eradicate. It just depends on the location.@@voxdomesticus
Most glyphosate labels provide specific guidance on this. For example, you might have to wait 3 days after an application before planting beans. Or, you wait 30 days after an application of glyphosate to plant a tomato plant. If you want to start an organic farm and sell organic produce, you must wait 3 years after the application of any synthetic fertilizer or pesticide (including glyphosate) to that ground. My general suggestion to people trying to eradicate knotweed is to plant locally grown native plants in the spring after a fall herbicide application to the knotweed. Then use selected excavation and the precise applications of herbicide to kill off surviving knotweed.
hello, I would like to use your products to get rid of japanese knotweed, I want to do foliar application. Can you advise on the proportions of the herbicide, foaming agent and possibly surfactant? there is no directions for the foliar application on the website (green shoots)Thank you
Marta - sorry about that. It's a little hard to find, but it's there! Here's the link: cdn.shopify.com/s/files/1/0848/5642/files/2022-GreenShootsGuidanceKnotweed.pdf?v=1660942014 . You don't need any additional surfactant. The Blue Foaming Agent contains a surfactant. If you have any questions after reading the guidance document, please let me know. We revise it periodically.
@@GreenShoots the stand I am going to be spraying is very small i will be using the small applicator from your site, any idea on proportions for that? or should I just aim for 2% concentration as well?
@@TheNightmart If you have a small plot, could you send me an email at john@greenshootsonline.com ? We have a new method that seems to work well - it's a bit more labor intensive but should work well for small plots.
Many perennials store carbohydrates in their underground rhizomes, roots, etc., starting in the autumn. This is especially true with knotweed. You want the herbicide to travel with the carbohydrates down into the underground rhizomes. That's why you apply in the fall. After the first year of application, you should have significantly less knotweed (about 90% should be dead). Killing the last 10% is the toughest, and therefore I recommend also digging those straggler plants and then treating again in the fall.
I have sprayed the plant this year and had a idea of what if I get a thick black tarp and lay it over the ground and "cook" the plant. I was wondering if this might work or even been tried?
Yes, this is one possibility. It has not worked well in the past however. This is a Nature Conservancy document that describes various methods for controlling knotweed. Look at p. 6 where the author discusses covering knotweed: www.invasive.org/gist/moredocs/polspp01.pdf
This will not work. I have tried this multiple times. It will punch through the tarp, go to the outside and between concrete, go dormant for years and still survive.
Shawna - It is best to apply the herbicide in the fall. That is the time when the knotweed plant is storing sugars in underground rhizomes. The plant takes the herbicide along with the sugars down to the rhizomes. At this time of year, if you want to do something, you can cut or bend the knotweed. Just make sure that if you cut it, you dispose of the stems properly. Roots can form from the cut green stems with sufficient moisture.
@greenshoots at this time of year (early june) do you recommend cutting now, versus diggiNg versus not touching until foam application in the fall? Thanks for the video, very helpful
You can try if any part of the stem is still green. Cut the stem down to that level and apply the herbicide to the green portion of the stem. Even if you have to cut very low, you may have some success.
If you are using a glyphosate herbicide (non-agricultural) in the U.S., its label will likely have a statement such as "Do not use on or around edible feed or food crops." Consumer glyphosate labels typically do not have restrictions on when humans or animals should be allowed into the treated area. I would not let humans or animals enter at least until it has fully dried. Just to be extra safe, you might restrict access for a week. Rain will affect treatment effectiveness. Generally, I try to make sure it's not going to rain for 24 hours, but the longer between treatment and rain, the better. I hope that helps JC!
just bought a house without know what this plant was. my mother and i did some research and found out it was this plant also known as Michigan bamboo and yeah got a spot of about 3600sq feet (120x30ish) of the stuff that's about 1/4 mile from a creek. would this still be applicable just on a much larger scale or should i just call a company and spend 10k on getting it gone?
That's definitely your call. 3600 sq ft is a lot but it can be tackled. The key is to start from the outside and move in. Knotweed does not reproduce from seed, so if you can contain the colony from the perimeter, you can eventually completely kill it. It will take more than one year. If an outside company does it, they will also have to come back in subsequent years. If someone tells you they can get rid of it with one application, be very skeptical.
@@GreenShoots After spending ten years on the frontlines of this war against the invasion of knotweed, I have found a way to kill knotweed with one treatment (well two) 75% of the time. What works for me is to spray the foliage and stems, stand back, wait for it to be absorbed and dry up in the sun. Once dry, spray it a second time. The second spray could be done hours or days later as long as it gets two treatments. Knotweed is a very thirsty plant. But remember we want it to drink the herbicide through it's leaves, not its roots.
@@knotweedkninja8539 which chemical do you use if i dont have to do the videos proccess that would save me a lot of time this year with the cutting and than burning
@@456456459 That would be Glyphosate, 2 oz per gallon. If the patch is real tall, go inside the patch first, start towards the front of the patch, spray all sides of each stem and the undersides of the leaves first as you work your way out of the patch, then spray over the top from all sides of the patch. Very important to adjust the spray nozzle as you go along. A bit more than a finer mist for close up leaves and stems and then open the nozzle a bit for the over top spraying. Be sure wear gloves, long sleeved shirt, protective eye wear and a hat.
Recently had a treatment done but we didnt cut it down it was inject with 2ml of pure glysophate direct into the stem in between the 1st and second node Lets see if this works
What happens if a hole is cut in the wall, 6" off the ground, of the thick stalk (used a razor) and the foam injected? This was my first try today. or better with a clean cut and get it onto the top of the cut?
Certainly killed it off, went all purple, upwards to the tip. I picked the thickest stalk in a spot. Trimmed the smaller stuff to the ground. This on the edge of a parking lot, so just leave it to bake out dry, the toss towards on a nearby spot for a compost. I imagine it will take until next spring to see if the blue injections spreads in the roots and runners and creates a dead zone.
@@williaml8474 Nice to hear! If you have more stems, definitely try your technique in early fall on the knotweed stems. That should be the best time of year. Interesting technique!
This edge area seems to have a reduced population. Kept the rest of this stand in check during the summer and fall with a hedge trimmer. Cleared the ground, with pitchfork and rake, of debris. Cut vines, except native grape, and cleared fallen wood. Counted 40 rings on 1 giant vine. In the summer/fall - moved deeper into this zone to a new stand of knot and vines covering the knot. Cut a path thru the center of the stand. Then a cross path. Then expanded in rings to clear a zone 100x100?, and piled all junk into like 4 compost piles. Found a lot of fallen rotted wood. Lots of bees when the knot was in flower. awesome. In the fall seeded the area with wildfowers seeds and left over tomatillos. The knot in this area will be visited for application soon. (In a separate patch, found a bee nest when stung a dozen times). Despite care got stung less on separate times, never found the ground nest, but treaded with more care. Expanded from these 2 zones, when other space is monoculture of English Ivy and many trees engulfed with same. Cutting a gap in the vines on each tree. :)
@@GreenShoots I tried the knotweed injector - its almost a necessity to pre-drill the stalks as the needle of the injector clogs when pushing through the stalk. Then the poison sprays everywhere. Last year I ordered the foaming kit from you, and with your advice, sprayed at the end of the season. I am happy to report a major reduction in knotweed on my property. It does seem to have grown stronger on my neighbors property. I will be telling them to order the same kit from you this year. Overall its much easier to spray, control, and identify what has been sprayed while using your product.
Glyphosate is generally the most effective herbicide against knotweed. That's what in Roundup. You will need pretty high-strength glyphosate, especially if you are treating the cut stems of the plant.
Never buy RoundUp brand herbicide. IT IS A RIPOFF! You can get a jug of glyphosate under many other brand names for a third of the cost at your local farm store. Don't forget to buy a sticker to add to the herbicide to help it stick to the plant leaves and stems.
I saw a video that recommended cutting then drilling down the middle of the shoot and filling with herbicide. What are your thoughts on this? Thanks for the great info!
That video was probably one showing an experiment I tried some years back. The technique seemed so promising because of the cavity inside the rhizome. Alas, it wasn't as effective as hoped. The best method for dealing with knotweed is still a foliar one. The technique described in this current video works well enough for small patches.
@GreenShoots Thank you! I've been trying for like 4 years but always cutting down in the spring and easy summer and trying the drill method. This time I bought some of your foam product and will cut in fall. Thank you!
@@philipstrobel6010 Yes, the aquatic approved herbicide we used was Killzall Aquatic. We used that with our blue foaming agent to create a foam herbicide. Just remember that in some states you may still need a permit.
Thanks for sharing. I have a questions and a comment. Have you ever eradicated(100% eliminated) a patch of knotweed (either through herbicide application or physical methods), or is population reduction the best we can hope for? I've not yet seen complete eradication through any method, except deep excavation. Also, I'm wondering at 3:36 if the patch shown is Japanese knotweed or rather Bohemian knotweed (the leaves are fairly long, with a cordate base, and the flower clusters are quite erect).
Thank you for this excellent comment, Elisabeth! I have not read about nor have I worked at a site where the complete eradication of knotweed has been confirmed with rigorous post-treatment monitoring over many years. I have mostly worked on sites in natural areas that are heavily infested. In those areas, complete eradication may not be possible with current methods (especially since deep excavation is not feasible at such sites). However, those sites can sustain vigorous native growth despite the “low-grade” presence of invasive knotweed. We have used glyphosate at most sites. At one site, we followed the initial glyphosate treatments with limited spot treatments with imazapyr to eliminate the knotweed stragglers that remained. We have avoided using imazapyr in the past because of its potential effect on nearby desirable natives. I will post if that approach has promise. What do you think about that approach? As to the patch appearing at 3:36, yes, I believe you are correct that that is Bohemian knotweed. It is confusing when I ask there for people to “make sure the targeted plant is indeed Japanese knotweed or is one of the four species of invasive knotweed commonly found in North America.” I should have just said, “Make sure the targeted plant is one of the four species of invasive knotweed . . ..” All the best!
So should I not be spraying all the little guys as they come up? Around 6"-18" I go out and spray them and they seem to die but is that just not effective since more little buggers just keep coming up?
What's critical is you actually want the plant healthy, growing and vigorous (to a certain extent) at the time of "killing". This is to give the best chance of the glyphosate being absorbed deeply by the plant and thus being able to kill the roots effectively.
Actually knotweed is much like say, a dandelion in your lawn. You see the dandelions blooming in your lawn in spring. It makes you mad so you spray but it doesn't really go away. You only killed what is above ground not the root below. However, if you want to really kill it you have to get past the urge to spray when the dandelion is blooming in your lawn and wait until late summer/early Fall. At this point the dandelion is directing all its energy downward to its root to store its reserves for the winter. This is the optimal time to spray any unwanted perennial, especially in knotweed's case, because to kill a knotweed plant you have to get that herbicide down into its huge root system. There is only a brief window of time each year to do this.... after it has bloomed up until two weeks before your first expected frost. Spraying any other time is a waste of herbicide, energy and time.
I am sorry, but I don't know. I have communicated with numerous people especially in Germany. As I understand it, there can even be restrictions on people who want to dig knotweed out. You might try continuously cutting the above-ground stems. Just be sure to dispose of the stems properly because of the potential for sprouting from the nodes of the cut stems.
Not that I know of, and, anything like this would be huge news. What I recommend to people who want to kill knotweed without chemicals (assuming the plot is not to big) is to dig up the rhizomes. This is hard work and requires persistence, and you need to be really careful. You don't want to distribute any portion of the knotweed or stems beyond the site. Otherwise, those pieces may re-root. Bag the rhizomes and cook them for a couple months in plastic bags.
Isn't there a way to kill japanese knotweed without using herbicides??? I have a hill supported by a 3 ft. high retaining wall. It's about 60 ft l x 8 ft d and it is covered with this invasive weed. I plan to put a small vegetable garden below the retaining wall in my yard. I can not use herbicides for this reason.
Yes, you absolutely can. It will be more work. Probably the best way is to excavate the rhizomes. Dig them out. Keep doing this until you have dug up all the rhizomes. Be very careful with disposal. If i dig them out, I put the rhizome pieces in black plastic bags until they are completely dead.
Been trying to find a way to get rid of about 1 mile worth on a creek bank myself. The only thing I could find was you have to dig up the land which can be as deep as 1 meter or more.
You can eradicate knotweed without chemicals. 1) Cut below the lowest node 3x a season - now mid/late May, late June/early July, and the end of August. (By September the nutrients have gone to the roots for the next year. 2) Bag in contractor bags and put out with the trash, 3) plant native plants after each clipping. It will take 3 years of this method and you’ll see fantastic results. You’ll still need some maintenance (same 3 cuttings) but the native plants will fill in beautifully. Visit nip the knotweed on FB for me. NO CHEMICALS. NO WEEDWHACKING. NO PULLING UP FROM ROOTS.
Great video, very informative! Only thing I'm going to pick on, is that Swansea (my home town) is a city in Wales, not in England. They're two seperate countries, both in the UK. To us it feels the same as somebody saying thr US and Canada are the same country.
Thank you! Yes, I have been rightfully taken to task in the past for this error. By the way, check out our other video on controlling a large stand of knotweed: ua-cam.com/video/YLo28mHgjH0/v-deo.html I promise no geographical errors in that video!
@@GreenShoots I didn't mean to sound angry/upset by the comment. Just as a friendly 'heads up'. I loved this video, very informative and will no doubt help me to treat the knotweed I have!
I live in upstate New York. My entire yard is nothing but japanese knotweed. This is WAYYYY too much work especially when my whole back hill is ALL knotweed. Any thoughts? We tried for 40 years to rid us of this fuck weed.
If you have a large knotweed monoculture, the best way to to treat it is with a foliar application. This can actually be done quickly and it's very effective.
Yes, that's a definite possibility. I have not seen much research but have talked with people who have used goats. They must be used repeatedly over a fairly long time to control knotweeds.
Thanks for the comment, WV Mike. With the method we recommend, cutting down the knotweed stems and treating the stems, the blossoms are not sprayed. Anyone who removes knotweed should replace it with native plants that will provide a more sustainable source of nectar and pollen.
I'm sorry to say but Glyphosate is NOT the best active ingredient to use. Rather, Imazapyr... The mode of action of Glyposate is NOT ideal for a plant that has a huge root-ball and Rhizomes. Imazapyr has the proper mode of action. I have used both and have treated acres of Knotweed-Japanese, Himalayan, Giant and Bohemian.
I take your point that imazapyr may work better at killing knotweed. I don't recommend it to homeowners for two reasons. First, it has high soil activity so it can kill non-target species. For a trained applicator, this is less a concern, but for a homeowner, improper use can lead to the death of desirable trees, etc. Second, because of that soil activity, it can take longer to replant a site treated with imazapyr. I have always found that it really helps to get natives planted quickly to compete with the knotweed.
If you have a big stand of knotweed, you can also do a foliar application. We will be publishing a video on how to do that. Basically, you spray the foam herbicide on the stems.
On this video: ua-cam.com/video/a_34PGCBQUk/v-deo.html by Post 10 4/13/22 @ 15:58 is a sign showing information about a control experiment at the missiquoi river basin (northern NY/VT) using mechanical control. wire mess put down before growth. Intially pushes thru, then chokes itself
I looked at the video clip you mentioned. Do you have any information on the result of the experiment using the mesh? It looks like the knotweed grew through the mesh and still may have flowered.
I would apply the herbicide twice in the fall of the first year. Thereafter, the same thing. Completely eliminating the stragglers can be tough. When you are down to just a few remaining knotweed plants, you might consider digging them out.
I tried something similar to this method, and it made matters worse. Also, glyphosates are illegal for non-professional use in most countries. The experts I've talked to all say the same: Don't "disturb" knotweed, it will only make it spread more. The only thing to do right now (2024) is to wait for effective methods to be developed.
One thing at the outset: this video is one of our older ones. We have new ones that I would recommend instead such as: Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html. To your point: there is overwhelming evidence in the scientific literature that a good application of glyphosate herbicide is very effective on knotweed. Jones et al. 2018 is a prime example. Especially if knotweed is growing along waterways it will spread downstream if it is not controlled. I have seen miles and miles of prime trout habitat ruined by knotweed monocultures on both sides of the stream. We have right now an adequate (although not ideal) method of control of knotweed.
Pamela - I realize people have concern about glyphosate. I have personally used it for decades; I follow the scientific literature pretty carefully. I am not a toxicologist by any stretch, but as I understand it - If you are someone who uses glyphosate as a professional every day, then there are reasons to be concerned. For the amount that I use it, I don't have concerns. Each person has to make their own decision of course. The good thing about glyphosate is that it is effective and it breaks down quickly in soils. This means, so long as you use it with precision, it has limited effects on the broader environment.
yea good luck with that. Knotweed grows through fucking asphalt pavement! You going to mix some baking soda and vinegar together and lay down a garbage bag?
Pamela, I'm a bee keeper and keep close tabs on the number of dead outs in our province each year. It's bad. Really bad, and only a fraction of the cost this is having on native bees, many which are near extinction or already extinct. The science is clear. These poisons are killing our biodiversity. They are also giving us a clue as to what these poisons are doing to us as they reach our groundwater. People like this are killing our planet, and killing us with it. Denialism allows people to opt out of saying what they actually think - this guy knows exactly what he's doing. He just doesn't care.
Lemme save you 8 minutes. Knotweed is knot a problem. All you gotta do is get some garden variety scissors, cut it into manageable portions and roll it into an expansion joint. I won't lie, the only unmanageable thing about knotweed is how high it gets you when you smoke it down. It's the highest I've ever been, my mind snapped like a carrot. You know it's pure when you see those orange flecks. Just seconds after smoking a knotweed blunt I was flying high man, I started licking walls and eating dog food. When I came to I'd blown a load in my pants and had to throw out my boxers. Put me in a state of vegetative regeneration for a week. It was well worth the sacrifice. This man is a card carrying pesticide pusher
I've just been single handedly whacking them with a shovel, digging them up (being careful not to break the damn shovel) and dropping the roots in a wheel barrel with a tarp. I will be sure to crush the stems into tiny pieces.
Keep us posted on how that goes. As you mention, people have to be especially careful with the cut vegetation because it can sprout easily especially near water or under damp conditions.
@@GreenShoots It's grown in two places which are thankfully not anything anyone would really walk on. There's a small colony in a sloped mulch patch between two driveways, that's been there at least as long as I've been alive, and I'm 25. it's been cut and even ripped out annually, which just ended up spreading it to the back edge of the property which is just waste/compost/brush area. It's not really that problematic to us at least other than it looks out of place, keeps spreading, and attracts a ton of bees and wasps briefly when it flowers, which the last thing we need to do is attract more wasps. I'm thinking of planting grass, lemon grass, or some kind of weed discouraging plant in the space cleared in the latter area, since its totally bare dirt.
@@gamerguy425 Yes, exactly as you have explained. If people cut or dig out the knotweed and then pile it in another location. They risk spreading the knotweed.
@@tobiask5131 There are two herbicides to consider other than glyphosate. If you don't live in the U.S., availability may be restricted especially for non-licensed applicators. The first is imazapyr; the second is aminopyralid. If either of these is available in your area, and you want to consider using one of them, read the product label very carefully before you buy. Both of these can leach from roots (of the target weed) and remain active in soils. Imazapyr for example can kill non-target plants such as evergreens.
@@GreenShoots interesting, I shall investigate this. Tho I suspect, since regulations are rather strict here in Sweden, they are most likely prohibited. Thanks for the tip!
That is of course your choice. I have not heard of mixing vinegar and baking soda. Horticultural vinegar by itself is used as a contact herbicide. It can kill the knotweed foliage. However, it will not do anything to the rhizome of the knotweed because nothing toxic to the knotweed from the vinegar will be translocated to the underground rhizome. (It really won't be any more effective than a mechanical cutting.) If you don't want to use herbicides, I would recommend an aggressive digging campaign coupled with careful disposal of the excavated crowns and green knotweed foliage. If you do this over several years, you should have good success.
Whether it is vinegar and baking soda or glyphosate, it is still a poison. The only difference is that you feel better when chemicals have names that you are comfortable with. If you doubt this fact? Explain why either mixture does the same thing? dead plants! If you are exposed to vinegar and baking soda long term you will probably have negative side effects. If either mixture is used in mass quantities and applied without common sense, the end result will be the same. Doubt this? dump your home made concoction in any aquarium and watch what happens. Just like glyphosate, all of the fish and amphibians will end up in Davey Jones locker. I am not trying to be ignorant here, I just want to dispel any misguided thought process' and present reality. Even if it does suck?
I hope the advice is helpful even if someone decides not to use our products. We are a very small company with a tiny ad budget. UA-cam is the best way to reach potential customers.
I had a patch of knotweed about 40' long by 6' wide growing on top of a lower retaining wall, it had reached about 6' tall. I sprayed it in late summer with liquid glyphosate and it completely eradicated it with one application. The large leaves have plenty of surface area for the glyphosate to cover. This simple apprach literally took me about 15 mintes to do. I was fortunate because I was working from an upper retaining wall about 6' above the top of the knotweed, so I was spraying down on top of it. I did this job about 5 years ago, and I continue to check the area annually for any signs of knotweed, so far there are none.
The approach shown in the video should be highly effective but would seem to be labor intensive. That said, I appreciate the 2 additional benefits of using this cut stem / foam herbicide method. First, you are exposing yourself to much less herbicide since it is not airborne; Second, you are putting much less herbicide into the environment since it is a highly targeted approach. I use this approach when I need to kill Asiatic bittersweet and other invasive vines as well as Tree of Heaven. So all that said, I would use this method on knotweed if you catch it early and there aren't already hundreds of stems. Moral of the story, keep a close eye on your property (especially wet areas) and catch knotweed early and it is easy to eradicate.
Excellent comments, Chris. The approach outlined in this video are definitely for small infestations. We do have a video for treating large knotweed infestations: ua-cam.com/video/YLo28mHgjH0/v-deo.html . That approach uses a foliar application of foam herbicide (glyphosate). I have found (and other research seems to support) that foliar applications are the most effective. They are just not as precise as you note.
What Spray did you use? Was it just a high concentrate of glyphosate? I have about double that area that covers both sides of a creek bank. Ive been fighting it for 3 years. It grows back faster then I can treat it. I always cut it down then treat it with round up with the Glyphosate. It lasts 3 weeks tops and the crap is growing back.
@@funkdaddyflex Treat in the fall. You will have much better luck. Check out our other video for treating a large patch of knotweed. ua-cam.com/video/YLo28mHgjH0/v-deo.html This video shows how you can do a foam foliar application.
@@funkdaddyflex I would recommend treating the knotweed only in the fall.
i have been using your product this past season and am happy ro report that although not completely gone has greatly reduced the amount of shoots - the greatest benefit i have found is that i can spot treat so specifically that it doesn’t destroy the lawn around it - using less poisonwith greater results - not to mention much more cost effective
Derek, Thank you so much for the comment! I am going to come out with a video and guidance document on dealing with "straggler" knotweed - i.e., those small knotweed plants that linger after an initial treatment.
Great information here. Thanks for creating this. Battled JKW on the farm, really got out of control before we realized what was happening. I did a lot of the cut/apply method. I found it VERY effective. I've almost got all of it eradicated after 4 years, but I still have to keep an eye out.
Thank you, Eric! It sounds like your treatments have been very effective. What you say about keeping an eye out for it is very important. I think many people think they have the JKW beaten, but it can slowly creep back.
I have seen patches, thought to be eradicated, return in the same spot 3 to 5 years later. Never stop rechecking a site for regrowth.
@@ericzipf1332 You may want to skip a year of treatment. The small stems remaining don't have enough surface area to kill the huge root which I guarantee is still surviving underground. Yes, I work for the local county noxious weed department where I am responsible for tracking down knotweed on thirty river miles, by myself, due to not enough grant money from the state to hire more workers. Though I doubt anyone is crazy enough to want to go through what I do in a day or more determined to save one section of a river or more outraged about losing all our rivers. Future generations will not know what river's natural authentic beauty looks like.
@@ericzipf1332 Actually we switched from glyphosate to Imazapyr three years ago, so Imazapyr is what I have had great success with as far as my double spray technique. I didn't mention it because the general public needs to stick with glyphosate. Believe it or not people, glyphosate is the safest herbicide on the market. No matter what you use... if the knotweed is anywhere near water you need a permit from Department of Ecology and a Pesticide Applicator license as well. Better off hiring a company who has the permit, license, knowledge and skill.
Was going out today to cut. Now I can wait til Fall. yeah! I have been successful with the buck thorn. This is a very informative UA-cam and product worked wonders. NO more buck thorn!! Thanks Jim
Thank you! I am really glad to hear that had success!
I am responding to a few of the comments below. First, glyphosate does work well on Japanese knotweed. Swansea University did the most comprehensive research to date on control methods for Japanese knotweed. According to that study: “Greatest control of aboveground F. japonica (Japanese knotweed) growth, defined by reduced basal cover and stem density . . . was obtained using glyphosate alone.” That study also found covering knotweed with plastic membrane the “least effective.” Link: link.springer.com/content/pdf/10.1007%2Fs10530-018-1684-5.pdf . Second, it is critical that a person apply glyphosate with accuracy, especially if there are nearby desirable plants. That is why foam herbicide works so well - you can kill just the non-native plant. Third, yes, I agree 100% that we are losing biodiversity. Japanese knotweed is one of the reasons. In any mature knotweed stand virtually NOTHING ELSE GROWS. If you remove a knotweed stand and plant native plants, that is a huge net positive.
Green Shoots where can I get the glyphosate Foam spray ?
You can get it from our website: www.greenshootsonline.com. However, it's only available in the U.S.
Helpful video. Ordering my kit now. Any updates on whether leaving the stem semi-attached helps with absorption and efficacy?
Jada, no update. We haven't had time to test that hypothesis more thoroughly.
Thank you for producing such an informative, easy to understand video. My neighbor and I both have wells, and also there is a pond about 100 yards downhill from the Japanese Knotweed stand whch is located between our properties. Is the herbicide safe to use in this case?
Mister Drummings - You are most welcome! Fortunately, this herbicide is generally immobile in soils because it binds tightly with them. This greatly reduces the potential for it to infiltrate groundwater. Your pond is also a good distance away from the application site. Assuming there is vegetation between the knotweed patch and the pond and assuming no literal "gully washer" the day of your application, you should be fine.
I also try to be extra safe and apply when rain isn't forecast for two days or more.
Hey, first, I really appreciate your videos. I have learned a lot already. Do you still suggest this method? I have watched your most recent video for homeowners and noticed that you don't mention this method.
As a general contractor, I'm looking to assist some clients with some small ish patches. We want to remove the plant material regardless, so it makes sense to be to follow this method where we'll cut the plants (after flowering and before frost), then apply a foaming herbicide to the cut stem tops.
Timely question! The method described in this video is easy for homeowners, and it allows immediate removal of the tall knotweed shoots from sight (a concern for many homeowners), BUT it is not as effective as other methods. I am going to revamp our guidance this winter to offer more treatment methods at different times of the year. While I still believe late fall after flowering but before frost) in a typical year is the best time to apply, it may not always be. Moreover, many homeowners are overwhelmed with large knotweed plots and can’t hire professional help. These people need a solution that allows them to start work on the knotweed plot earlier in the year. So, you’ll see more videos from Green Shoots soon!
Thank you, just ordered your foam product! So we have this behind our garage, moved to this house two years ago and I didn’t think much of it until I finally decided to research what this plant is. So now that spring time is coming should I start using the glyphosate on the shoots once they begin to spout? Or should I wait till fall after the plant is done flowering? Thanks again for making this video and getting the information out there!
You are most welcome! I would wait until fall to do your treatments. I know that's a long wait. However, the knotweed plant is putting all its energy into pushing sugars into the foliage. It's hard to fight against that current to get herbicide down into the rhizomes.
Thank you so much for this
I have it taking over everywhere
I’m gonna try this.
Good luck, Ali!
So very helpful! Thank you 🙏 it’s on my neighbor’s property opposite his fence!!! On my side is my garden , about 5feet from fence. We constantly fight it, effectively… now that I know what it is….going 👉 to look for how to confront that… this will be a people problem not envasive plant 🌱 🤦🏻♀️
Yes, if a neighboring property owner doesn't want to control it, that can be an ongoing problem. You might consider a root barrier.
Interesting and informative video, thank you. Please note, though, that Swansea University is not in England, it is in Wales. It's like saying Vienna is in Germany. or calling a Canadian American. They are different. Wales is a country in its own right
If I could, I would correct that mistake. It stands out like a sore thumb. I do apologize.
Did you know that Japanese Knotweed is used to save trees? They are making Japanese Knotweed paper in Europe.
Also research Japanese Knotweed Permaculture where it is used as an amazing fertilizer.
Check out my 'Japanese Knotweed Garden' video. I was badly mis-sold on this house and garden but Japanese Knotweed has been a miracle plant. Bamboo is far worse.
Research Swansea University Wales and how they promote Student Prostitution to our poor children. If they can do that, are they really people you can trust? I think not.
I appreciate all the help offered on this site! You mentioned to let the knotweed grow after mid-summer...does this include all the little shoots that I find in the area where I was digging up roots (before I really knew what I was dealing with!)? And just treat each of those individual shoots in the early fall as well as the larger stands that I can get at? Also, I was given some advice to cut off and discard the flowers when they come out--they said that would at least help diminish one way that they spread. Do you recommend that too? Thank
After midsummer, let all the knotweed grow. Then treat it all in the fall. Just make sure you hit all the stems. You could cut off the blossoms. There isn't much evidence of knotweed spreading by seed, but cutting off the blossoms can't hurt.
A very good video! - Very informative. Thank you from South Wales, UK
Thank you so much for the support! As you know, many of us in other parts of the world look to the university in Swansea for guidance on knotweed.
By the way, I will be coming out with a new video on stem wiping. Stem wiping more closely uses the same route of herbicide uptake as foliar applications which are very effective in killing knotweed. All the best!
@green shoots Thank you for your video. I have giant knotweed along a creek in my backyard. I know complete eradication is impossible, but I would like to control it in my section of the creek, restore it with native plants & help control erosion. I am using the cut & foam herbicide method so it won't get in the water. I don't know that I will get to all of it this year, is it ok to do it over many seasons? Also the parks department recommended I immediately plant fast growing trees to try to shade new growth out. Do you recommend that? Or wait to the spring? Do you have recommendations for what type of tree would be good for the creek bank to prevent erosion but could also shade out the knotweed growth? Most of the the other things growing in the area are also woody invasives, but there are a few blaack walnut trees. I am in NE Ohio zone 6. Thanks for your help. I know it will take years...
Alysia, yes, you can definitely do the work over a period of years. Just move from the periphery into the center and treat the stuff nearest the shore. If you can get another treatment in before the beginning of winter, that would be optimal. Yes, I think your Parks Department made a good recommendation to plant native trees. In one area we restored, volunteers planted river birch. They are beautiful trees, grow peand have done a great job of keeping down the knotweed. Ideally, plant the trees at least some distance from treated knotweed 5-10 feet perhaps. The black walnuts may themselves inhibit the growth of knotweed and any other natives you plant.
Thank you for this video. It is just the beginning of summer here in New England. As of right now, I'm trying to uproot any shoots that are loose enough. I will do the application in the Fall. One question, though: Once the weed dries inside the plastic bag, how do I dispose of it? trash? Compost? I have some shoots from last season that are dry and I would love to know how to dispose of them safely. Thanks.
After about 2-3 months in a bag, the rhizomes and shoots should be dead. Therefore, you should be able to compost them. You should monitor the pile. I wouldn't spread the material around. One study from England found that desiccating plants for 38 days resulted in no regrowth. Lawson et al 2021. However, that was under laboratory circumstances so I would do the drying for a little longer.
Im going to buy your product and try it this fall! In the meantime what can be done? Ive been pulling it, putting it in thick contractor bags and garbage cans with lids until it dies clmpletely next season. Then Ive been throwing a bunch of roundup on it and covering it with thick tarps to smother. Recently bought a new house last year, and my neighbors yard is infested with it and they do nothing about it ! Ruined my attempts at a garden last year.
My recommended option in the spring is to dig out the knotweed. See Link below. I would not put a tarp on it. It seems that just causes the knotweed to go dormant. I also would not apply herbicide right now. The herbicide will not translocate to the underground rhizome. This video ("3 Simple Steps) is a bit out of date. Check out our newest one - also below. Good luck!
Control Knotweed by Excavating or Digging Crowns ua-cam.com/video/k7WgGRiodIc/v-deo.htmlsi=4v5frUOC7vwj6qOY
Knotweed Control for Homeowners: 4 Tips for Success!
ua-cam.com/video/LIpUXuCU6GE/v-deo.html
I treated my knotweed last year the same way as you have showed in the vdeo. This year i have very little regrowth. My question is how do you know when you its 100% dead. I am planning to build over the infected site and would like peace of mind
That's great to hear! I recommend digging up the remaining plants that are still alive. Now that you have killed most of the stand, this should be quite a bit easier.
There's a good article from May 8, 2019, in Slate that discusses the problem with knotweed. It quotes Robert Naczi, a curator of North American botany at the New York Botanical Garden": The biggest problem with knotweed, Naczi explained, is that it grows so thickly there is no room for anything else. “I don’t want to ascribe moral agency to the plant,” he says. “It’s not an evil plant. It’s doing what a plant does. But Japanese knotweed is a very serious invasive. A very, very problematic species. One of the worst invasive species in Northeastern North America.” Here's the link to the article: slate.com/technology/2019/05/japanese-knotweed-invasive-plants.html?.
Thanks for all your extremely helpful information. We have a huge stand of Japanese Knotweed in our backyard and did the initial application of your blue foam glyphosate in two applications last fall (we are in Maine). We had great success and this spring have been removing, and carting away, all the dead canes. With all the crowns now exposed, we can see where knotweed is growing back and so are embarking on digging up as many crowns as possible. My question is: Are there any plants we can plant in this space over the summer that can fill in the area--hold their own with any sprouting knotweed--that could serve as foundational plants as we slowly transform this large space into a flower garden? We realize this will take "a while" but would like to start cultivating some non-knotweed plants along the way.
AH - That's great to hear! That is a very good idea to get something in there soon so that any surviving knotweed has competition. For temporary, natural covers, many landscapers, etc., use an annual ryegrass. That is one possibility. Just buy it from a good source so the ryegrass doesn't have weed seed in it. Mow it before it sets seed. You might also consider planting some of your garden perennials in areas that are pretty clear of knotweed. If you decide to plant native prairie plants, they will compete really well. Trees or tall plants that provide maximum shade would provide the best competition over the long term, but only if that's what you want at the site.
Canada goldenrod is by far the most aggressive and persistent native plant in my opinion (and is very ecologically beneficial). If there is any plant that can compete with an invasive, that would be it. A few other ideas would be yarrow (preferably the wild type), native asters, woodland sunflowers, and/or milkweed (common milkweed, Asclepias syriaca, might be a good bet)
Enjoyed the video, very informative. I live in Swansea, so I know there have been a lot of studies here to find the best way to control it.
Thank you so much. I hope the researchers at Swansea University are doing follow-ups to their earlier research - which was excellent!
Great video! I have some of this growing in my backyard in Vermont. When we cut the shutes and apply herbicide foam, do we do that once a year for multiple years or should I apply it for multiple days consecutively?
And then burn the cut shutes?
Thank you! You should apply the foam herbicide to the cut stems in the fall. Apply it to every knotweed stem you can find. You can certainly burn the cut stems or pile them up. Since you will be doing this in the fall, it's much less likely they will re-root. The next spring you will have some re-sprouts. You can dig those up and apply foam herbicide again the fall to anything that is left.
Hi, thanks so much for all the precious information. We have two big patches on both side of our house. We will start a treatment in the Fall. In the meantime, we are wondering if there are any State resources that you are aware of to help people deal with such thing, or any private companies. We are in Chittenden county, Vermont.
It is generally pretty difficult to get financial assistance for invasive removal work done on private property. Some localities have tool sharing programs or small grants. Many private companies do invasive plant removal, although in many cases they typically do work on a large scale. Make sure you hire someone who has experience doing knotweed removal.
Getting ready to try this in a few weeks. Some of it is coming up through the lawn, I’m a little worried about killing grass if I cut it really low and try to dab the foam on right down by the ground. Is there another method for a situation like that?
That method you just described works quite. You might also cut the grass around the knotweed stem. Only if you hit the green part of the grass will you kill it.
Hello , so glad i found your video - have been actively researching JKW ever since we identified it on our property. We live in New England and it's still spring here - the weeds are already 3 ft tall - if we cut and foam treat them now and then again treat shoots in Fall ( before frost ) - will that impact the effectiveness vs only treating them once before the Fall ?
I worry if we cut and treat more than once a year - it might encourage more growth underground ? is that possible ?
I wouldn't bother treating now with herbicide. If you do anything at this time of year, I would recommend digging up the crowns. I know this can be arduous, but it's probably the best way to slow the knotweed down at this time. If you do dig up the knotweed, be very careful with the dug up rhizomes. You don't want them to re-sprout. Put them in a black plastic bag and set them in the sun to "cook them." Don't dig near a waterway. At the end of our other video, you can see how to dig up the crowns: Control a Large Stand of Japanese Knotweed in 4 Phases: ua-cam.com/video/YLo28mHgjH0/v-deo.html . Don't feel you have to dig up all the rhizomes. Just attack as many as you can and then treat in the fall.
There is controversy about whether cutting helps or causes the stand spread out more. If you do cut, be sure to be careful with the cut stems. Store them where they won't re-sprout. I personally think digging works better as noted above.
Good information. Thank you! Not as nightmarish if you know it can be killed.
You are most welcome, Michael. It can be killed. It will take more than one season but it can be controlled.
Keep Concentrated or dilute per directions? Can you clarify if I use the KILLZALL super concentrate straight from the bottle or dilute 5 tbs per gallon ?
Good question. Sorry for the late response. Did you take a look at our more recent video on direct application to the knotweed stems? The techniques described work better than the cut stem method: Knotweed Control for Homeowners: 4 Tips for Success!
ua-cam.com/video/LIpUXuCU6GE/v-deo.html
My husband and I purchased a house last year in the winter and shortly after the snow melted discovered we had a knotweed infestation. We have a small stream that runs behind our house that the knotweed seems to be quite attached to. This year it has started encroaching further into our yard toward the driveway. In my frustration i chopped a bunch of the stalks down as close to the ground as possible and plan on burning it once it dries out.
I wish i had seen this video before making the effort haha
What do you recommend to keep it from coming further into the yard while it grows before a fall herbicide application? Im afraid if we do nothing it will keep coming closer to the house and become even more of a headache.
In the Spring I recommend digging out the knotweed crowns. View our video on this: Control Knotweed by Excavating or Digging Crowns ua-cam.com/video/k7WgGRiodIc/v-deo.htmlsi=4v5frUOC7vwj6qOY. Also, view our blog post which has the latest resources we offer on dealing with knotweed.
greenshootsnews.blog/2024/04/25/invasive-knotweed-green-shoots-has-new-products-and-resources-for-dealing-with-it/
Thank you for responding!
@@ashleywnukowski1261 most welcome!
what is the best way to Dispose of all the knotweed plants once you've cut/poisoned the stems?
I just used your product to poison about a 40x10 foot section but now have a pile of plants. (I originally was planning on cutting each stem and poisoning but after several hours and only making it through about 1/5th of the patch I decided to go with applying the foam to the plant itself and leaving it).
and will the dead stalks from the winter season be able to reproduce?
thanks in advance for your help
No the dead stalks will not be able to reproduce. You should be just fine leaving them in place on the ground. We are experimenting with some other methods that will be faster than cutting and treating. However, it sounds like you made it through the full patch!
i have tons of this stuff, what a battle.. the dry stuff in the spring goes up like gasoline, all started cause of previous owner thought a 'bamboo' hedge looked nice..grrr!
Thanks, I been looking for help like this. I have close to 1/3-1/2 of an acre of this nightmare. I live close to a river in Connecticut so should I get the Aquatic Precision Foam or the other.
You are welcome! Yes, you should get the aquatic herbicide if you are treating any knotweed that is right along the water. I would treat those stems immediately along the shore with the cut stump method just to avoid spraying anything into the water. (Or, dig the stems out.) Also, when you apply to knotweed that's within about 8 feet of the shoreline, spray toward the shore. Check Connecticut law regarding aquatic applications of herbicides. Some states require a licensed applicator. Good luck!
I'm developing a plan to manage the Japanese knotweed on my property. I have a few questions.
1. It is late May now, should I refrain from dealing with the knotweed in any way until fall? (Edit: I just saw your response to a similar question below)
2. Would there be any benefit to combining your method with covers/tarps to prohibit photosynthesis? Or is this unnecessary and/or ineffective?
Question 1: I think digging works best early in the year because you are removing the most amount of viable knotweed tissue. It then forces dormant buds to grow which you can treat in the fall. Question 2: covering can as you mention inhibit photosynthesis but it can also induce dormancy. Dormant knotweed can reportedly survive for years. If you do cover it, I would uncover it in early to mid-summer so that you have enough foliage to treat in the fall. Good luck!
Would this work if I do this now (May)? I’m in Massachusetts. I have small patch that growing right now. TIA
May is not a good time to treat - too early. Check out our newer videos such as:
Knotweed Control for Homeowners: 4 Tips for Success!
ua-cam.com/video/LIpUXuCU6GE/v-deo.html
Also, if you want to do something early in the year look at:
Control Knotweed by Excavating or Digging Crowns ua-cam.com/video/k7WgGRiodIc/v-deo.htmlsi=4v5frUOC7vwj6qOY
I have a decently sized patch growing in the sidewalk next to my house. Should I do the treatment before the fall and then again in the fall?
Should I wait until the fall to do anything?
Should I cut the stalks down and then do the full treatment in the fall?
I'm worried about it spreading into my yard.
Given your circumstances, I would recommend leaving it alone until fall. Anything you do now might encourage spreading. Just monitor your yard to make sure you don't see young plants. If you do, take them out with a traditional dandelion digger or other similar implement.
Hi John, very good informative video(s)! I also saw a couple of videos on extinction of weed with electricity. Seems to be mostly used in UK and to some extent in trials in Germany. The idea being to electrocute the plant down to the root with high voltage. What do you think of this "weed zapping" method? Also glyphosate is mostly banned for private use here in Germany. Roundup, e.g., is available only with Pelargon Acid. Do you happen to know, if this is as effective as glyphosate? Thanks! Markus
Sorry, another question: Some herbizide producer recommend cutting off the plant and then applying it to the inside after scratching the cell tissue. They recommend using a pipette. Bit laborsome, but would this work?
Thank you, Markus! I have followed the weed zapping methods fairly closely. However, I haven't seen any studies where it has been used. I have not been able to see a demo of it yet. It would be fantastic to have another method for killing invasive knotweed. As to glyphosate with pelargonic acid - this is likely not a helpful addition. One study found that with foliar applications to various weeds, "longer-term control and control of regrowth was either not affected or reduced by the addition of PA" (pelargonic acid). Wehtje et al 2009. The likely problem is that pelargonic acid destroys the vascular system in foliage before all the glyphosate is translocated. Do applications of a concentrated mix of glyphosate and pelargonic acid to the stems as we suggest in our UA-cam video: Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html I have noticed much less harm to vascular tissue when an application of a "hot mix" is done to the veins or to stems as opposed to leaves.
@@markusgrune6841 This might work. However, I agree with you - it would require a lot of work! Generally, as mentioned in the Notes above for this video, I now discourage doing cut stem treatments with knotweed. I would advocate instead a direct application of a concentrated herbicide to the exterior stem tissue. Or, you could do injections. Or, if you have a bigger patch, do foliar applications.
Wow, thank you so much for the extensive advice! If I happen to buy a weed zapper, I will record the process and the results and share it with the community here! Cheers! Markus
@@markusgrune6841 Please do! I would be very interested to hear how it works!
Spent 5 hours pulling the knot weed out by the roots, guess I didn't get some of the roots and it's growing back strong. Hope this works, flamethrower and kerosene method is the last resort.
Pulling or digging is not a bad method. If you apply herbicide in the fall, you should have good success at getting rid of most of it!
Hello, we have a BIG patch of JKW, at least 50m2,growing on our neighbors lot, it's a close as 1-2m from our fence. It's been there for +10 years and had been covered in tarpes about 10 years ago but has started growing again. It was in a shaded area but we didn't know and started cutting trees and bushes last year before we noticed it. The JKW got exponentially bigger and thicker this year because of the light exposure. We can't treat it because it's not on our land. Would you recommend digging in a root barrier and maybe excavating our property? I going crazy standing around doing nothing waiting for it to pop up in our garden. We're trying to create some shade again in the meantime.
Just check out how to eat the stuff. There are videos. It's the most concentrated source of resveratol. East Asians use it for food and medicine. The spring shoots are edible.
If you have no knotweed on your property, a well constructed root barrier could prevent the knotweed from entering your property. Some sources say knotweed rhizomes go down as far as 2 meters or about 6 feet. That's probably unusual. However, you'll want to put the barrier down pretty deep. I know there are article available on root barriers - one from Wagar and Barker 1993. If you do any excavation, be very careful. The rhizome fragments can easily reroot. Keep the excavated soil in that same location.
Hello, I have few patches of knotweed around my property. One patch 30 ft x 30 ft is located on a rocky hill, no matter how long I let them grow the stems don’t get thicker, on average they are 1/8-1/4 of an inch and they are just dispersed through the area. Would cut the stem and treat work for such a thin steam or should I use foliage application? Thank you
Generally a foliage application is more effective. A cut stem application to knotweed is the most precise. If you wipe foam herbicide on the leaves and stems (covering about 30% of the plant), the application will be effective and quite precise.
excellent advice
Thank you so much!
Thanks for the advice, one point though, Swansea University is in Wales (UK) not ENGLAND
Yes, Others have noted that error, and I appreciate the correction.
Thanks for the video! Sorry if this is a dumb question, but what do I do with the dead seeming, dried out portions of the plant? Is it ok to just pull them up and burn them?
That's a good question! Yes, you can burn them or compost the dried stems. The seeds could be viable, but that is not the typical way that knotweed spreads. Just keep any live stems away from moist conditions.
Hello, I treated large area of Japanese Knotweed (maybe 75' x 75') in the fall of 2022 with arduous cutting, bagging and immediate precise application of your green shoots weed killer and foaming agent into the cut stems. This spring 2023 there is re-growth of the knotweed, some of the shoots are small while others are already thick and tall. I am committed to stay on top of the problem. My next steps are unclear. I am not at the location daily, planning and long drives are required to get to the site. What is the best approach for my next steps this spring to control and eradicate the species? Is covering the area this spring with a black tarp effective - helpful in any way or is it ineffective? Exactly what are the best next steps in the my approach to the knotweed this spring, summer and coming fall? You talk about planing native plants to the area, is this done now, is application of grass seed and effective native plant. I Appreciate your time and response.
Linda, at this point, after having knocked it back, you want to do everything you can to weaken the knotweed patch (the clone). This could include this spring and early summer: digging, cutting, and even covering and then in the fall doing another treatment. Digging out the crowns will be the most effective - but most arduous. If you cut, be sure to cut and then also take a hoe and destroy the winter buds that are at the base of each stem - these are thumbnail size buds that will sprout once the stems are cut. You could then cover some of the most vigorous parts of the patch while you are gone with tarp to slow growth further. Finally, in early mid-summer, let the knotweed grow and treat in the fall. With a patch this large, I recommend people do a foliar application of foam to the knotweed. A foliar application is most effective. Feel free to contact me directly if you have any other questions too!
I've heard injecting the base of the trunk w/ a strong mix of water/glyphosate salts is a good method, using something like a cooking "brine" or "marinade" injector. What are your opinions to this approach?
Peter, yes, that method definitely works. What I don't like about it is that it uses so much herbicide! According to Swansea University, this method uses 15 times more than other methods such as foliar applications. That much glyphosate can potentially affect nearby plants (even though glyphosate binds tightly to soils).
@@GreenShoots Actually, injection or cut and pour down the shoot, contains the herbicide inside the hollow shoot as long as you don't spill. But your right, this type of treatment requires undiluted herbicide. Fine for small clumps but not for large infestations. When I have done cut stem I would cut the stem half way through 3 or 4 nodes up, bend the top of the stem over leaving a part still attached to the stem, ram a thin rod down the shoot to break through the nodes, then I put a few squirts of undiluted herbicide down each hole using a hand sprayer. I figure when you open the nodes with a rod the herbicide goes right down to the root. Foliar application is still the best option and gets the best results. I have had to cut a tunnel through fifty feet of briars just to reach the knotweed. All I could do was bring a spray bottle and lopers with me and all I had access to was the lower stem under all those briars. Knotweed grows in the most unimaginable places. It never fails, when I am going that extra mile to find knotweed, wondering what the Heck am I doing trapped in some Hellish brush hole, ready to give up and turn back... there it is! I hate knotweed with a passion. One thing folks should know is, the first time you spray knotweed is seems overwhelming because of it's height but every year thereafter the clump you spraed will be stunted in growth and require less herbicide to re-treat the following years.
Birds are in abundance where my stand of knotweed is so I would like to approach it with the cut method. You replied to another comment that cut/apply is more precise, but less effective. How would you compare the two methods in terms of effectiveness? Roughly what ratio of treatments can one expect to achieve the same level of effectiveness?
Also, you mention that cutting prior to fall treatment does not affect effectiveness. If I have a stand that is thick with old, dead canes, would it be wise to do a mid-june cutting to make access for fall treatment easier. My plan would be to cut new growth to 2 ft and dead canes to the ground.
I would say roughly a foliar treatment can achieve 80 to 95% effectiveness, same with injection. Cut stem is probably 65 to 80%. I will be publishing a video on knotweed stem wiping with foam herbicide. This method is more precise and the effectiveness seems to be closer to a foliar application.
@@ambahgirl I would definitely try to remove the old canes now. The stand will get really dense by fall. I generally like to bend knotweed stems to create better access if you can, but you can trim too if that helps.
Would you suggest the cut stem method if wildlife is a concern? Or if we can manage to keep most critters away until it dries would that be sufficient? Thank you so much for your wealth of information.
@@ambahgirl I am going to do an upcoming video on stem wiping of herbicide on knotweed. That is a very targeted method of application - similar to cut stem in that way, but it should be more effective than cut stem. Generally, however, you are right - once the herbicide dries, it won't be a big concern for wildlife.
Hi from Pennsylvania! It looks like I will have to do a foliar application because the area is so large. If I tackle this job THIS fall, will it be possible to plant the following spring (with the understanding I will probably have to get in there to spot treat) or will having done a foliar application kinda "salt" the soil?
Your instincts are exactly right! This fall, do the foliar treatments (spaced about 2 weeks apart) as we recommend in our Large Stand of Knotweed video: ua-cam.com/video/YLo28mHgjH0/v-deo.html . In the spring you can (and should!) plant. Trees and shrubs will compete best. But other native plants will also do well once established. Spot treatments will be needed next fall. When you are digging to plant be careful. Isolate any dug up knotweed crowns or green stems. A foliar application uses the least amount of herbicide and yet evidence indicates it works the best.
@@GreenShoots thank you so....SO much!
@@ksero1000 you are most welcome!
Should I apply foam to tiny knotweed plants as well? Is there a size of stem cutoff for when you foam?
This fall when you do your treatment, apply foam to all the knotweed stems. Also, i recommend our new video: Knotweed Control for Homeowners: 4 Tips for Success!
ua-cam.com/video/LIpUXuCU6GE/v-deo.html You will have more success with the foam herbicide wiping technique explained there.
Green shoots...when you say to treat in the fall, what is the time frame you're talking about? I am in Massachusetts and have knotweed coming into my yard from neighbors and an area of woods behind the house. I've been digging up roots where I can all spring and am developing an eagle eye for new shoots poking through which I have been digging up as well. Should I just continue to do that through the summer? And then when in the fall is it best to treat? September-October? Thanks!
Yes, that is a good approach - to dig up the knotweed through about mid-summer. At that point, let the knotweed grow and then apply in the fall. You want to do your application before a killing frost. If you are doing a cut stem treatment as outlined in this video, do the treatment about 2 weeks before any expected frost. Maybe, in mid to late September for you?
I’m getting ready to treat JKW with glyphosate before the first frost I have 2 questions, 1) Should I be adding something to make it stick to the JKW?
2) Should I put a tarp over it after I treat it for the winter?
No, don't put a tarp over the treated area. Our foam herbicide system has a surfactant that helps the foam stick really well. You want something like that to ensure good contact and adhesion. Most glyphosate (except aquatic versions) have some kind of surfactant mixed in.
Thank you!
I have it on the side of my yard near my neighbors fence in upstate NY, I do not have the correct tools to completely remove it from the ground by the roots, so I have been removing it from the bottom of the stem with a large knife, i recently moved all of the cut stems (most around 5-6ft high stems) to the area between mine and my neighbors yard to block off view from my neighbors yard into mine, did I make a mistake by doing so? Will it spread into my neighbors yard? And what are your recommendations on what to do with it all and how to effectively remove it without the correct tools?
Just so I understand - you are cutting off the tops of the knotweed? If so, that can work. Just keep doing it until about midsummer. Then stop and let it grow. You want enough to treat it in the fall. If you don't want to use herbicide, you will have to keep cutting it for several seasons. Just make sure you store the cut stems in a place where they cannot re-root.
@@GreenShoots no I have been cutting them from the bottoms as close to the root as I can get to, the roots are so far in the ground that I cannot pull them out unless the plant is dying, I moved them in between the space next to mine and my neighbors yard so it blocks the two yards from connecting, I’m curious as to if they will re root and begin to grow in my neighbors yard, they are currently laying on there sides after being cut but they are in grass, will they re root where I have them now?
@@jeffsmith2846 The cut knotweed could re-root, especially if it has adequate moisture. Just try to keep the cut parts as dry as possible.
I'm sure there's a comment in here somewhere about it but if there a time and a place for a weed whacking, perhaps in the spring? Or does that just cause it to spread more?
I generally don't recommend repeated mowing as a control method. It requires repeated mowings every year over many years. More importantly, as you mention, it create a risk of spread. If you are in a relatively dry area, you could try it. Just monitor the site. And, if you are near a water body and there is any chance of offsite movement, definitely don't cut knotweed.
Simply beautiful. Many thx.
Well, thank you!
Also, should I cut the stems on the go through the summer before applying the herbicide in the Fall to weaken the plant, or should I just wait in the Fall to do anything?
You can cut them but one cutting probably won't do much. I generally recommend people dig out the rhizomes if that's feasible, and then treat in the fall. If your patch is larger, you might consider a foliar application. A foliar application is the most effective but is less precise. The cut stem application is more precise but less effective.
@@GreenShoots Thanks for your answer!
@@christophebernard9118 You are most welcome!
With a large stand of knotweed (170 feet wide) that is 9-12 feet tall, is it best to knock it down and then attempt foliar application or does that break the stalks thereby impeding uptake of glyphosate? We are unsure if we should chop and apply or knock and apply. Any advice appreciated!
I would knock and apply as opposed to chopping and applying. That seems to work best.
If it makes it easier, bend, don't break, then spray. However, it makes it harder to cover every inch of each plant.
To tackle a huge patch like you have, (make a few trails first on the inside and also blaze a trail around the perimeter), start inside the clump and spray all the stems first, then start at the back and work your way out spraying the undersides of the leaves. Next, go around the perimeter of the patch, carefully spraying all the leaves around the outer edge. Lastly, open your nozzle to full stream and spray over the top of the patch from all sides. Take heart, next year the knotweed will be stunted and easier to spray.
1)The ultimate date for spraying Knotweed is on or around September 15, after the bees are done pollinating.
2) Use 2 ounces Glyphosate and one ounce of a sticker per gallon.
3) Tighten your nozzle to just more than a mist (depending on distance away from the plant) and cover every inch of each plant, first the stem, then leaves and undersides of leaves too if at all possible.
4) The silver bullet to eradicating knotweed is this... when you are done thoroughly spraying... wait for the herbicide to be totally absorbed/dry and spray it all over again one more time! (2nd spray could be done the next day.)
After only having 10 percent eradication of the knotweed clumps I treated year after year (for 10 years)... I finally used the double spray in one day technique and found 90% eradication the following season.
@@knotweedkninja8539 thank you so much for the detailed recommendations. Making this harder is the fact that this stand of knotweed is located atop and astride a steep berm, and contains a morass of old blackberry and knotweed cane underneath it!
@@sarahlebo4746 You will need to cut the blackberry up into little bits with loppers to have clear access to the knotweed. The canes can be crunched down. I love the sound of knotweed crunching. With enough determination you will be able to do it. If nothing else, stand on top of the berm, open the nozzle and spray as far as you can over the top. Sometimes that is all you can do. Hopefully there isn't a creek below. Another option if it is too steep for you to navigate with a backpack sprayer, although very time consuming, is to mix glyphosate with water 50/50, put it in a hand sprayer, cut one stem at a time, 16 inches high, ram a skinny rod down the stalk to break the seal at each node then spray down inside the tube. It is not as effective as far as eradicating but it will make the knotweed shorter next year/easier to spray. I read somewhere this technique can be done up until it freezes. I may try it myself on a patch in a few days.
We moved onto five acres in 2018. It's been a labor of love trying to get the place fixed up to be wildlife friendly.
Last obstacle: 2 of our 5 acres is CHOKED OUT with knotweed!!
For an infestation that large, check out our other UA-cam video: Control a Large Stand of Japanese Knotweed in 4 Phases:
ua-cam.com/video/YLo28mHgjH0/v-deo.html The method described there will really help you get this infestation under control. Good luck and so glad to hear you are restoring 5 acres!
Great information, thanks
Any suggestions on disposing of the cut/ dug up parts of knotweed? Right now my brush pile is pretty high with all that I have taken out and I have found that some of it is starting to grow from the pile. Placed it in a barrel last year but it grew from that as well.
Hi Gerard, I've been dealing with eradicating JKW from our farm. I've almost got it all gone. What I have done is keep canes and roots separate. The canes are laid out on black plastic in the sun to dry out. I don't pile them up too deep so there is good air flow to dry. Once they turn brown, they are no longer viable. With any root material, I store that in metal tubs in my barn, in the dark. I try to remove as much dirt as possible to speed drying. Roots take some time to dry out, but they will. Once everything is dry, I usually just burn it all up.
As you have discovered, if you just dig this stuff up and make a pile out of it like 'normal' weeds, you'll effectively just move your problem around and then you'll have two spots to deal with. The drying process is a little bit of a nuisance, but it's the only way. I actually try to avoid digging up the roots and disturbing it, I generally use the cut/spray stump method of eradication, but best choice is very site dependent.
i have usually put it in plastic bags and placed those in the sun for several weeks. It takes a while but you will eventually see a white mold growing on it. That means it is pretty dead.
I thought about hauling mine to the corner of my ex's property lol
@@ericzipf1332 Why is a problem disturbing roots while digging?
The roots can get really deep and it can be problematic to dig it out. If you miss any root, it'll just come back. There is no one answer that fits all situations. I use both chemical and mechanical means to eradicate. It just depends on the location.@@voxdomesticus
After knotweed is controlled using glyphosate, would other plants do well in the area? Could you ever grow food?
Most glyphosate labels provide specific guidance on this. For example, you might have to wait 3 days after an application before planting beans. Or, you wait 30 days after an application of glyphosate to plant a tomato plant. If you want to start an organic farm and sell organic produce, you must wait 3 years after the application of any synthetic fertilizer or pesticide (including glyphosate) to that ground. My general suggestion to people trying to eradicate knotweed is to plant locally grown native plants in the spring after a fall herbicide application to the knotweed. Then use selected excavation and the precise applications of herbicide to kill off surviving knotweed.
hello, I would like to use your products to get rid of japanese knotweed, I want to do foliar application. Can you advise on the proportions of the herbicide, foaming agent and possibly surfactant? there is no directions for the foliar application on the website (green shoots)Thank you
Marta - sorry about that. It's a little hard to find, but it's there! Here's the link: cdn.shopify.com/s/files/1/0848/5642/files/2022-GreenShootsGuidanceKnotweed.pdf?v=1660942014 . You don't need any additional surfactant. The Blue Foaming Agent contains a surfactant. If you have any questions after reading the guidance document, please let me know. We revise it periodically.
@@GreenShoots the stand I am going to be spraying is very small i will be using the small applicator from your site, any idea on proportions for that? or should I just aim for 2% concentration as well?
@@TheNightmart If you have a small plot, could you send me an email at john@greenshootsonline.com ? We have a new method that seems to work well - it's a bit more labor intensive but should work well for small plots.
Can you please explain why doing it in the fall ? And should I do it untill first frost? Shoul I do it every year?
Many perennials store carbohydrates in their underground rhizomes, roots, etc., starting in the autumn. This is especially true with knotweed. You want the herbicide to travel with the carbohydrates down into the underground rhizomes. That's why you apply in the fall. After the first year of application, you should have significantly less knotweed (about 90% should be dead). Killing the last 10% is the toughest, and therefore I recommend also digging those straggler plants and then treating again in the fall.
I have sprayed the plant this year and had a idea of what if I get a thick black tarp and lay it over the ground and "cook" the plant. I was wondering if this might work or even been tried?
Yes, this is one possibility. It has not worked well in the past however. This is a Nature Conservancy document that describes various methods for controlling knotweed. Look at p. 6 where the author discusses covering knotweed: www.invasive.org/gist/moredocs/polspp01.pdf
This will not work. I have tried this multiple times. It will punch through the tarp, go to the outside and between concrete, go dormant for years and still survive.
Is it safe to burn the stems and leaves removed in your method rather than put them in black plastic bags?
That's a viable alternative, certainly.
Do you know of any companies that tackle it? We bought a property and had no idea it had at least 2-3 acres of this on it.
Where are you located?
where are you located?
Can you do this process now - in the spring- or does it have to be fall to be effective?
Shawna - It is best to apply the herbicide in the fall. That is the time when the knotweed plant is storing sugars in underground rhizomes. The plant takes the herbicide along with the sugars down to the rhizomes. At this time of year, if you want to do something, you can cut or bend the knotweed. Just make sure that if you cut it, you dispose of the stems properly. Roots can form from the cut green stems with sufficient moisture.
@greenshoots at this time of year (early june) do you recommend cutting now, versus diggiNg versus not touching until foam application in the fall? Thanks for the video, very helpful
It’s 11/22 my stems are brown and the leaves are all almost off. Is it too late for me to apply my purchased herbicide?
You can try if any part of the stem is still green. Cut the stem down to that level and apply the herbicide to the green portion of the stem. Even if you have to cut very low, you may have some success.
Will the herbicide be harmful if cattle or other farm animals get into it after the application? Will rain affect the effectiveness of the treatment?
If you are using a glyphosate herbicide (non-agricultural) in the U.S., its label will likely have a statement such as "Do not use on or around edible feed or food crops." Consumer glyphosate labels typically do not have restrictions on when humans or animals should be allowed into the treated area. I would not let humans or animals enter at least until it has fully dried. Just to be extra safe, you might restrict access for a week. Rain will affect treatment effectiveness. Generally, I try to make sure it's not going to rain for 24 hours, but the longer between treatment and rain, the better. I hope that helps JC!
just bought a house without know what this plant was. my mother and i did some research and found out it was this plant also known as Michigan bamboo and yeah got a spot of about 3600sq feet (120x30ish) of the stuff that's about 1/4 mile from a creek. would this still be applicable just on a much larger scale or should i just call a company and spend 10k on getting it gone?
That's definitely your call. 3600 sq ft is a lot but it can be tackled. The key is to start from the outside and move in. Knotweed does not reproduce from seed, so if you can contain the colony from the perimeter, you can eventually completely kill it. It will take more than one year. If an outside company does it, they will also have to come back in subsequent years. If someone tells you they can get rid of it with one application, be very skeptical.
@@GreenShoots After spending ten years on the frontlines of this war against the invasion of knotweed, I have found a way to kill knotweed with one treatment (well two) 75% of the time. What works for me is to spray the foliage and stems, stand back, wait for it to be absorbed and dry up in the sun. Once dry, spray it a second time. The second spray could be done hours or days later as long as it gets two treatments. Knotweed is a very thirsty plant. But remember we want it to drink the herbicide through it's leaves, not its roots.
@@knotweedkninja8539 which chemical do you use if i dont have to do the videos proccess that would save me a lot of time this year with the cutting and than burning
@@456456459 That would be Glyphosate, 2 oz per gallon. If the patch is real tall, go inside the patch first, start towards the front of the patch, spray all sides of each stem and the undersides of the leaves first as you work your way out of the patch, then spray over the top from all sides of the patch. Very important to adjust the spray nozzle as you go along. A bit more than a finer mist for close up leaves and stems and then open the nozzle a bit for the over top spraying. Be sure wear gloves, long sleeved shirt, protective eye wear and a hat.
@@GreenShoots Japanese knotweed definetely reproduce from seeds very well, be careful.
Recently had a treatment done but we didnt cut it down it was inject with 2ml of pure glysophate direct into the stem in between the 1st and second node
Lets see if this works
that can work too. It's a little tougher for small stems.
@@GreenShoots i agree was a little tougher have 3 size needles worked a treat
I also sprayed all the stems i did so we can monitor it
@@PegasusDevelopments That is key to treat the ones that can't be injected. Smart move.
@@GreenShootsCan it be inject into roots?
@@PegasusDevelopmentsAny success?
What happens if a hole is cut in the wall, 6" off the ground, of the thick stalk (used a razor) and the foam injected?
This was my first try today.
or better with a clean cut and get it onto the top of the cut?
William - are you going to try this technique? If you do, please let me know how it turns out!
Certainly killed it off, went all purple, upwards to the tip. I picked the thickest stalk in a spot. Trimmed the smaller stuff to the ground.
This on the edge of a parking lot, so just leave it to bake out dry, the toss towards on a nearby spot for a compost.
I imagine it will take until next spring to see if the blue injections spreads in the roots and runners and creates a dead zone.
@@williaml8474 Nice to hear! If you have more stems, definitely try your technique in early fall on the knotweed stems. That should be the best time of year. Interesting technique!
Any updates?
This edge area seems to have a reduced population.
Kept the rest of this stand in check during the summer and fall with a hedge trimmer.
Cleared the ground, with pitchfork and rake, of debris. Cut vines, except native grape, and cleared fallen wood. Counted 40 rings on 1 giant vine.
In the summer/fall - moved deeper into this zone to a new stand of knot and vines covering the knot. Cut a path thru the center of the stand. Then a cross path. Then expanded in rings to clear a zone 100x100?, and piled all junk into like 4 compost piles. Found a lot of fallen rotted wood. Lots of bees when the knot was in flower. awesome. In the fall seeded the area with wildfowers seeds and left over tomatillos. The knot in this area will be visited for application soon.
(In a separate patch, found a bee nest when stung a dozen times). Despite care got stung less on separate times, never found the ground nest, but treaded with more care.
Expanded from these 2 zones, when other space is monoculture of English Ivy and many trees engulfed with same. Cutting a gap in the vines on each tree. :)
I wonder if you can drill and inject the plants to keep the vascular tissue as intact as possible
That's an interesting question. I have not tried a drill before. If you do try it, please let me know how it worked!
@@GreenShoots I tried the knotweed injector - its almost a necessity to pre-drill the stalks as the needle of the injector clogs when pushing through the stalk. Then the poison sprays everywhere. Last year I ordered the foaming kit from you, and with your advice, sprayed at the end of the season. I am happy to report a major reduction in knotweed on my property. It does seem to have grown stronger on my neighbors property. I will be telling them to order the same kit from you this year. Overall its much easier to spray, control, and identify what has been sprayed while using your product.
Somebody told me to use round-up a couple days ago. Dirs it work also?
Glyphosate is generally the most effective herbicide against knotweed. That's what in Roundup. You will need pretty high-strength glyphosate, especially if you are treating the cut stems of the plant.
Roundup is just a brand name for glyphosate. Like kleenex is for tissues.
Never buy RoundUp brand herbicide. IT IS A RIPOFF! You can get a jug of glyphosate under many other brand names for a third of the cost at your local farm store. Don't forget to buy a sticker to add to the herbicide to help it stick to the plant leaves and stems.
@Knotweed Kninja what do you suggest for a “sticker”?
Thanks great video
I saw a video that recommended cutting then drilling down the middle of the shoot and filling with herbicide. What are your thoughts on this? Thanks for the great info!
That video was probably one showing an experiment I tried some years back. The technique seemed so promising because of the cavity inside the rhizome. Alas, it wasn't as effective as hoped. The best method for dealing with knotweed is still a foliar one. The technique described in this current video works well enough for small patches.
@GreenShoots Thank you! I've been trying for like 4 years but always cutting down in the spring and easy summer and trying the drill method. This time I bought some of your foam product and will cut in fall. Thank you!
I see you've done this by a water source. Is this safe to apply along creeks, river edge?
Near the water, we used an aquatic approved herbicide. In some states you may need a permit or you may have to hire someone.
@@GreenShoots would you be able to provide a link to what this is? Thanks
@@philipstrobel6010 Yes, the aquatic approved herbicide we used was Killzall Aquatic. We used that with our blue foaming agent to create a foam herbicide. Just remember that in some states you may still need a permit.
Very good video! Help people who have the knotweed problem!
Thank you! I will reach out.
Most Welcome!
Thanks for sharing. I have a questions and a comment. Have you ever eradicated(100% eliminated) a patch of knotweed (either through herbicide application or physical methods), or is population reduction the best we can hope for? I've not yet seen complete eradication through any method, except deep excavation. Also, I'm wondering at 3:36 if the patch shown is Japanese knotweed or rather Bohemian knotweed (the leaves are fairly long, with a cordate base, and the flower clusters are quite erect).
Thank you for this excellent comment, Elisabeth! I have not read about nor have I worked at a site where the complete eradication of knotweed has been confirmed with rigorous post-treatment monitoring over many years. I have mostly worked on sites in natural areas that are heavily infested. In those areas, complete eradication may not be possible with current methods (especially since deep excavation is not feasible at such sites). However, those sites can sustain vigorous native growth despite the “low-grade” presence of invasive knotweed. We have used glyphosate at most sites. At one site, we followed the initial glyphosate treatments with limited spot treatments with imazapyr to eliminate the knotweed stragglers that remained. We have avoided using imazapyr in the past because of its potential effect on nearby desirable natives. I will post if that approach has promise. What do you think about that approach? As to the patch appearing at 3:36, yes, I believe you are correct that that is Bohemian knotweed. It is confusing when I ask there for people to “make sure the targeted plant is indeed Japanese knotweed or is one of the four species of invasive knotweed commonly found in North America.” I should have just said, “Make sure the targeted plant is one of the four species of invasive knotweed . . ..” All the best!
So should I not be spraying all the little guys as they come up? Around 6"-18" I go out and spray them and they seem to die but is that just not effective since more little buggers just keep coming up?
At this time of year, it is probably just as effective to cut them down. (Just make sure you dispose of properly.) Then apply herbicide in the fall.
@@GreenShoots ok thanks I will try that. Killed 2/5 patches over the last 3 years. Last 3 were bigger and giving more of a fight.
Good luck!
What's critical is you actually want the plant healthy, growing and vigorous (to a certain extent) at the time of "killing". This is to give the best chance of the glyphosate being absorbed deeply by the plant and thus being able to kill the roots effectively.
Actually knotweed is much like say, a dandelion in your lawn. You see the dandelions blooming in your lawn in spring. It makes you mad so you spray but it doesn't really go away. You only killed what is above ground not the root below. However, if you want to really kill it you have to get past the urge to spray when the dandelion is blooming in your lawn and wait until late summer/early Fall. At this point the dandelion is directing all its energy downward to its root to store its reserves for the winter. This is the optimal time to spray any unwanted perennial, especially in knotweed's case, because to kill a knotweed plant you have to get that herbicide down into its huge root system. There is only a brief window of time each year to do this.... after it has bloomed up until two weeks before your first expected frost. Spraying any other time is a waste of herbicide, energy and time.
Will agent orange work?
What's the product called? Is it available in the UK?
Unfortunately, Frank, it is not available in the UK at this time.
Any glycophosphate weed killer will do.
Look on Amazon.
I got 5 litres of the stuff for £25. I little goes a long way.
Would this be shipped to sweden, u think it is illegal?
Sorry, we don't offer the product in Europe at this time.
@@GreenShoots any idea what I can do with my knotweed over in Europe then?
I am sorry, but I don't know. I have communicated with numerous people especially in Germany. As I understand it, there can even be restrictions on people who want to dig knotweed out. You might try continuously cutting the above-ground stems. Just be sure to dispose of the stems properly because of the potential for sprouting from the nodes of the cut stems.
Multispek mutvimanex you need to kontakt miljöteknik
Is there any sort of natural remedy that you could inject into freshly cut knotweed stems that would kill them? Maybe a wood ash solution?
Not that I know of, and, anything like this would be huge news. What I recommend to people who want to kill knotweed without chemicals (assuming the plot is not to big) is to dig up the rhizomes. This is hard work and requires persistence, and you need to be really careful. You don't want to distribute any portion of the knotweed or stems beyond the site. Otherwise, those pieces may re-root. Bag the rhizomes and cook them for a couple months in plastic bags.
Isn't there a way to kill japanese knotweed without using herbicides??? I have a hill supported by a 3 ft. high retaining wall. It's about 60 ft l x 8 ft d and it is covered with this invasive weed. I plan to put a small vegetable garden below the retaining wall in my yard. I can not use herbicides for this reason.
Yes, you absolutely can. It will be more work. Probably the best way is to excavate the rhizomes. Dig them out. Keep doing this until you have dug up all the rhizomes. Be very careful with disposal. If i dig them out, I put the rhizome pieces in black plastic bags until they are completely dead.
Don’t dig up rhizomes. At each breaking point another plant can start. See our tried and true method above.
Been trying to find a way to get rid of about 1 mile worth on a creek bank myself. The only thing I could find was you have to dig up the land which can be as deep as 1 meter or more.
You can still have a garden after using herbicide.
You can eradicate knotweed without chemicals. 1) Cut below the lowest node 3x a season - now mid/late May, late June/early July, and the end of August. (By September the nutrients have gone to the roots for the next year. 2) Bag in contractor bags and put out with the trash, 3) plant native plants after each clipping. It will take 3 years of this method and you’ll see fantastic results. You’ll still need some maintenance (same 3 cuttings) but the native plants will fill in beautifully. Visit nip the knotweed on FB for me. NO CHEMICALS. NO WEEDWHACKING. NO PULLING UP FROM ROOTS.
Great video, very informative! Only thing I'm going to pick on, is that Swansea (my home town) is a city in Wales, not in England. They're two seperate countries, both in the UK. To us it feels the same as somebody saying thr US and Canada are the same country.
Thank you! Yes, I have been rightfully taken to task in the past for this error. By the way, check out our other video on controlling a large stand of knotweed: ua-cam.com/video/YLo28mHgjH0/v-deo.html I promise no geographical errors in that video!
By the way, I did edit out the mistake.
@@GreenShoots I didn't mean to sound angry/upset by the comment. Just as a friendly 'heads up'. I loved this video, very informative and will no doubt help me to treat the knotweed I have!
@@howells442 I appreciated the comment! Thank you!
I live in upstate New York. My entire yard is nothing but japanese knotweed. This is WAYYYY too much work especially when my whole back hill is ALL knotweed. Any thoughts? We tried for 40 years to rid us of this fuck weed.
If you have a large knotweed monoculture, the best way to to treat it is with a foliar application. This can actually be done quickly and it's very effective.
@@GreenShoots How? What is the treatment and results? Can I plant grass and mow? Any opinion on the Swisher predator lawn brush hog?
@anderslberg3360 ..and, have you had success with digging weed or it regrow over and over again?
Will goats eat it?
Yes, that's a definite possibility. I have not seen much research but have talked with people who have used goats. They must be used repeatedly over a fairly long time to control knotweeds.
Do not spray knotweed in August and September when it is blooming. Honey bees and native pollinators use it as a major nectar and pollen source.
e360.yale.edu/features/bee-alert-is-a-controversial-herbicide-harming-honeybees
Thanks for the comment, WV Mike. With the method we recommend, cutting down the knotweed stems and treating the stems, the blossoms are not sprayed. Anyone who removes knotweed should replace it with native plants that will provide a more sustainable source of nectar and pollen.
You have to cut it and spray it before it blooms or you're already too late. There's plenty of other flowers for the bees.
I'm sorry to say but Glyphosate is NOT the best active ingredient to use. Rather, Imazapyr... The mode of action of Glyposate is NOT ideal for a plant that has a huge root-ball and Rhizomes. Imazapyr has the proper mode of action. I have used both and have treated acres of Knotweed-Japanese, Himalayan, Giant and Bohemian.
I take your point that imazapyr may work better at killing knotweed. I don't recommend it to homeowners for two reasons. First, it has high soil activity so it can kill non-target species. For a trained applicator, this is less a concern, but for a homeowner, improper use can lead to the death of desirable trees, etc. Second, because of that soil activity, it can take longer to replant a site treated with imazapyr. I have always found that it really helps to get natives planted quickly to compete with the knotweed.
WOW so simple you just cut it and spay stuff on the stems... looks out at the thousands I have to get rid of.
If you have a big stand of knotweed, you can also do a foliar application. We will be publishing a video on how to do that. Basically, you spray the foam herbicide on the stems.
@@GreenShoots I order a Guandao I found cheap that was shown to cut bamboo so I am just going to use anger to deal with them =D
Where can I buy this stuff to kill the knotweed, that has already cost me $1000
You can buy it at www.greenshootsonline.com
On this video: ua-cam.com/video/a_34PGCBQUk/v-deo.html
by Post 10 4/13/22 @ 15:58 is a sign showing information about a control experiment at the missiquoi river basin (northern NY/VT) using mechanical control. wire mess put down before growth. Intially pushes thru, then chokes itself
I looked at the video clip you mentioned. Do you have any information on the result of the experiment using the mesh? It looks like the knotweed grew through the mesh and still may have flowered.
@@GreenShoots - Sorry, no further info.
5:40 reference marker
How often to do this? Once a year?
I would apply the herbicide twice in the fall of the first year. Thereafter, the same thing. Completely eliminating the stragglers can be tough. When you are down to just a few remaining knotweed plants, you might consider digging them out.
I tried something similar to this method, and it made matters worse. Also, glyphosates are illegal for non-professional use in most countries. The experts I've talked to all say the same: Don't "disturb" knotweed, it will only make it spread more. The only thing to do right now (2024) is to wait for effective methods to be developed.
One thing at the outset: this video is one of our older ones. We have new ones that I would recommend instead such as: Knotweed Control for Homeowners: 4 Tips for Success! ua-cam.com/video/LIpUXuCU6GE/v-deo.html. To your point: there is overwhelming evidence in the scientific literature that a good application of glyphosate herbicide is very effective on knotweed. Jones et al. 2018 is a prime example. Especially if knotweed is growing along waterways it will spread downstream if it is not controlled. I have seen miles and miles of prime trout habitat ruined by knotweed monocultures on both sides of the stream. We have right now an adequate (although not ideal) method of control of knotweed.
I used a machete looool
That works too.
I listened until u said glysophate
Pamela - I realize people have concern about glyphosate. I have personally used it for decades; I follow the scientific literature pretty carefully. I am not a toxicologist by any stretch, but as I understand it - If you are someone who uses glyphosate as a professional every day, then there are reasons to be concerned. For the amount that I use it, I don't have concerns. Each person has to make their own decision of course. The good thing about glyphosate is that it is effective and it breaks down quickly in soils. This means, so long as you use it with precision, it has limited effects on the broader environment.
yea good luck with that. Knotweed grows through fucking asphalt pavement! You going to mix some baking soda and vinegar together and lay down a garbage bag?
Pamela, I'm a bee keeper and keep close tabs on the number of dead outs in our province each year. It's bad. Really bad, and only a fraction of the cost this is having on native bees, many which are near extinction or already extinct. The science is clear. These poisons are killing our biodiversity. They are also giving us a clue as to what these poisons are doing to us as they reach our groundwater. People like this are killing our planet, and killing us with it. Denialism allows people to opt out of saying what they actually think - this guy knows exactly what he's doing. He just doesn't care.
@@digginz8603 Lol!
@@lizazawadzka1535 So, why are you watching....?
Lemme save you 8 minutes. Knotweed is knot a problem. All you gotta do is get some garden variety scissors, cut it into manageable portions and roll it into an expansion joint.
I won't lie, the only unmanageable thing about knotweed is how high it gets you when you smoke it down. It's the highest I've ever been, my mind snapped like a carrot. You know it's pure when you see those orange flecks.
Just seconds after smoking a knotweed blunt I was flying high man, I started licking walls and eating dog food. When I came to I'd blown a load in my pants and had to throw out my boxers. Put me in a state of vegetative regeneration for a week. It was well worth the sacrifice. This man is a card carrying pesticide pusher
Omg what really?
@@weast2123 Oh yes.
Omg 😸
Please don't open a dispensary!
@@GreenShoots ngl I was plastered off my face when I wrote this and completely forgot this was a thing 😂 I'm rolling
I've just been single handedly whacking them with a shovel, digging them up (being careful not to break the damn shovel) and dropping the roots in a wheel barrel with a tarp. I will be sure to crush the stems into tiny pieces.
Keep us posted on how that goes. As you mention, people have to be especially careful with the cut vegetation because it can sprout easily especially near water or under damp conditions.
@@GreenShoots It's grown in two places which are thankfully not anything anyone would really walk on. There's a small colony in a sloped mulch patch between two driveways, that's been there at least as long as I've been alive, and I'm 25. it's been cut and even ripped out annually, which just ended up spreading it to the back edge of the property which is just waste/compost/brush area.
It's not really that problematic to us at least other than it looks out of place, keeps spreading, and attracts a ton of bees and wasps briefly when it flowers, which the last thing we need to do is attract more wasps. I'm thinking of planting grass, lemon grass, or some kind of weed discouraging plant in the space cleared in the latter area, since its totally bare dirt.
@@gamerguy425 Yes, exactly as you have explained. If people cut or dig out the knotweed and then pile it in another location. They risk spreading the knotweed.
@gamerguy425 Have you had success?
Glyphosate? That’s sooo unhealthy! Absolutely not an option for us.
Glyphosate is perfectly safe when used with proper PPE...
You have no idea what you're talking about. It's absolutely safe when applied properly and as intended. Don't drink it.
Glyphosate is forbidden where I live ... :)
Do you want a recommendation on a different herbicide or a non-chemical method?
@@GreenShootsAbsolutely, I want these off my property! They are considered invasive here, it's a bother..
@@tobiask5131 There are two herbicides to consider other than glyphosate. If you don't live in the U.S., availability may be restricted especially for non-licensed applicators. The first is imazapyr; the second is aminopyralid. If either of these is available in your area, and you want to consider using one of them, read the product label very carefully before you buy. Both of these can leach from roots (of the target weed) and remain active in soils. Imazapyr for example can kill non-target plants such as evergreens.
@@GreenShoots interesting, I shall investigate this. Tho I suspect, since regulations are rather strict here in Sweden, they are most likely prohibited. Thanks for the tip!
@@tobiask5131 You are most welcome, Tobias!
Why not just use vinegar and baking soda? I refuse to uuse poison
That is of course your choice. I have not heard of mixing vinegar and baking soda. Horticultural vinegar by itself is used as a contact herbicide. It can kill the knotweed foliage. However, it will not do anything to the rhizome of the knotweed because nothing toxic to the knotweed from the vinegar will be translocated to the underground rhizome. (It really won't be any more effective than a mechanical cutting.) If you don't want to use herbicides, I would recommend an aggressive digging campaign coupled with careful disposal of the excavated crowns and green knotweed foliage. If you do this over several years, you should have good success.
Whether it is vinegar and baking soda or glyphosate, it is still a poison. The only difference is that you feel better when chemicals have names that you are comfortable with.
If you doubt this fact? Explain why either mixture does the same thing? dead plants! If you are exposed to vinegar and baking soda long term you will probably have negative side effects.
If either mixture is used in mass quantities and applied without common sense, the end result will be the same. Doubt this? dump your home made concoction in any aquarium and watch what happens.
Just like glyphosate, all of the fish and amphibians will end up in Davey Jones locker. I am not trying to be ignorant here, I just want to dispel any misguided thought process' and present reality. Even if it does suck?
Green Shoots advert !!!
I hope the advice is helpful even if someone decides not to use our products. We are a very small company with a tiny ad budget. UA-cam is the best way to reach potential customers.