We treated an acre's worth of knotweed last fall. So far, with the exception of tiny shoots cropping here and there, we have not seen any substantial growth. Before spraying, we had spent the entire summer, almost every day, sometimes twice a day, hitting every plant with a scythe. Doing this, we deprived the plant an opportunity to photosynthesize leaves and feed the rhizomes. In one stand of knotweed in adjoining property that we treated,, the entire sprayed knotweed stand is dead with the exception of those few rootballs to the rear of the dense patch that we missed. These had grown to approximately a foot. Our plan with these is to keep them down until October, and re-spray. Lest we think we're just behind, much of the rest of the town has spurious growth going on. So far, so pleased.
That's great to hear! Sounds like you really went after those knotweed. I can think of a couple of advantages to your method: First, by cutting so often, you gave the plant no chance to start storing energy in the rhizomes. It may also be that with so many cuttings, the aerial shoots may not have developed the ability to sprout roots. That could prevent spreading even if the cut aerial shoots contacted moist ground. (Don't know for sure though.) You might also consider digging up the remaining knotweed crowns this spring and early summer. You could have it wiped out by this winter!
as an update, we have had only sporadic growth (the rest of our road has over two feet high growth) of tiny shoots with deformed leaves. These are easily pulled. I have also uprooted any root balls that seem to have no life in them and relinquish their grip quite easily (whereas last summer, they were quite tenacious). Native plants are beginning to naturally encroach. I have also planted buckwheat and spring wheat as a fast cover crop to begin to cover the bare patches of dirt left from the huge knotweed stand we have taken down.
@@pmaher63 Oh hello, I have a knotweed infestation I am trying to get rid of as well. I have a question about your successful method. . As you were so fastidious in cutting down the knotweed in the summer, did the plants eventually flower? My plan was to knock the plants down in June and let them grow and flower and then spray with herbicide in the fall after flowering.. This is because I understand that the optimum time to spray is after flowering. I have knocked down a stand of knot weed in the first half of June and now 2 weeks later I've already got 3 'and even 4 'plants! I am trying to decide if I want to let it grow back, flower and spray or use your method of continuous cutting.
@@robertschoenberg3972 I didn’t let it get tall at all so that it would be easier to treat in the fall. My stand was one acre of an impenetrable thicket of JK.
Most informative. I had read or seen the info about late summer application 2 years ago, and hit our stands in late September, just once, with a very strong mix of glyphosate and a large sprayer, on a calm morning. Unfortunately the sprayer got damaged so it didn't get done last year. But the single application was quite effective last year. This spring I am seeing a few plants coming up, so will follow the same approach this fall. The largest area is on a near 2 to 1 slope, so I don't know what natives can work there.
If you are replanting a slope, pretty much any native will work there - if there's sufficient sunlight and you can do the work on that slope. It is hard to maintain however. Maybe native shrubs? You can create little planting areas with small retaining walls.
Thanks for this video. I used your tips and applied glyphosate gel (roundup) right before the first frost on a stand of knotweed in my garden. I have not seen a single leaf of knotweed in the year since. Btw this was in Stockholm, Sweden.
You are welcome, Rambler Rose! I will pass that compliment on to the people who made that fast delivery happen. Waiting while having to watch an invasive plant grow is tough, I know. But you'll thank yourself for having done so next spring.
Hi John thanks for very useful videos. I have learned a lot from you about Japanese knotweed! plant!. I, have one question for you, I live in Canada and how come I can't buy the (Blu foam agent only). And I am not interested in any Roundup or chemicals just the blue foam agent. Thank you very much John.
There are some ongoing studies - for example, one at the University of Minnesota being conducted by Alan Smith where they are doing a comprehensive analysis of knotweed control including the use of genetic analysis. These should make a big difference in the coming years.
Yes, just use the aquatic version of glyphosate. Depending on where you live (which state) there may be restrictions on who can apply herbicides near or on water.
Hey there, I've been watching your videos and ordered a glyphosate kit from you. I have 1.43 acres, and probably a full quarter of it (maybe slightly more) is knotweed. The property had been mowed when I bought it so I didn't know about the problem until the land was mine. It is growing in several sections of the property, near my leach field, and just all over the place. A couple of questions: My neighbors both have it growing on the edges of their property as well. One neighbor is dead set against using glyphosate, so it will still be growing right next to my property. Should I try to push the issue with her a bit more? Because I really would like to try to eradicate it. It seems stupid to just let it keep growing. Second, is it necessary to dig up all of the rhizomes after you spray and the foliage dies?? I have a LOT of knotweed. I don't know if I'm capable of digging up that much stuff. In addition to the knotweed growing on the open meadow part of the property, there is a large stand of trees between mine and my other neighbors property. The knotweed is VERY tall and fully growing throughout the stand of trees. Would it be ok to address the stuff on the open areas first, and try next year to get the stuff in the stand of trees? There are many little flowers that are interspersed in the knotweed, so although currently in Maine, the flowers on the knotweed have gone by, there are still flowers in and around it from other plants, so there are bees still present. Is it ok to wait a bit longer before I spray? I really don't want to kill bees. Thanks so much for your videos.
With a large stand, the key is deciding where to start. First, based on your description, the leach field is the most pressing. You definitely don't want knotweed invading it because it could damage the perforated pipes. I would create a knotweed free perimeter around the leach field and keep expanding it. Second, to protect desirable plants like wildflowers, you can do spot treatments with precise applications of foam herbicide to the stems of the knotweed near desirable species. On our website under "resources" and "knotweed" you can sign up for our guides. Check out our Knotweed Guide No. 1: How to control a small stand of knotweed. You can apply foam herbicide directly onto the green part of the stems. As described in the Guide apply rings of foam around the stem near the base. If you have the time, you can even rub the stem with a gloved hand to remove dirt and increase the absorption of the herbicide into the green stem and apply just one or two rings of foam herbicide. Third, in terms of timing, you want to make sure your last application is at least a day or so before a killing frost. This is hard to predict, of course, but you can find out first frost dates in your area by searching for the "Farmers Almanac first frost." I recommend two applications spaced about two weeks apart. With the second application, you only apply foam herbicide to the green parts of the knotweed foliage. If the foliage is yellow or a very pale green, it won’t absorb much herbicide. I hope this helps!
@@GreenShoots Thank you so much! So, I should be focused on application on the stems? I was under the impression to do the leaves. There are SO many plants. It's really overwhelming. I can't believe how many there are. But, I agree that protecting the leach field is my priority right now. I really appreciate your videos and advice. Thanks again.
Hey, I’m about to tackle my knotweed invasion. My question is: the plants are alrdy really talk and bushy. Shall I cut them down now so I can treat them more effective in fall? Maybe burn the cut sticks in a big fire pit or shall I just let it grow until fall? It’s alrdy way taller than I am. Thank you in advance. Also will it damage my Peach tree next to the knotweed with the foam? Really appreciate your knowledge.
I advise against cutting. The plants seem to take up the herbicide better if they are not cut. We now offer a "conversion kit" for our Large Foam Dispenser that allows you to attach a streaming nozzle. This allows you to stream a liquid. This stream can be lofted high and the allowed to rain down on the knotweed. This is better than a spray of liquid or foam for the really tall plants. Professionals use a wand extension but this really isn't feasible for homeowners. Use a more precise method near your peach tree (such as a direct application to the stems). Create a buffer around the peach tree using the more precise method.
We recommend cutting and treating the cut stems for small infestations. This method is more accurate. However, for large infestations, foliar applications of foam herbicide work the best. The foliar method is both the quickest and most effective. Therefore, if accuracy is not so critical, use the foliar method.
I had a stand bordering a 20 car parking lot - so towering - impractical to park. Gradually cut to ground level, left foliage to bake on the asphalt. Some smaller root clumps pulled up and dirt shaken off before drying. The dried stuff tossed back into a bare spot. Nothing grew out of that stuff. The towering plants further back from edge of the lot were injected with small foam applicator, mid-last summer, 2021. In 2022, the injected did not come back, those closest to the edge remained small Cars now started parking there. Tall ones further back, 15 ft, from the edge, were injected, 6 inches above ground level, in October, a few weeks later the entire foliage yellowed. Will see come 2023. Used a soil knife to cut a Hole in the stem. Have to assume it is over much, but tried to fill the entire cell, 2-4 pumps of the small pump container.
Using your product and it’s great - thanks for the video! The house I purchased has knotweed growing all through the lawn. It was clear cut and the lawn reseeded before I purchased, but predictably the knotweed is growing back already. I need to be able to mow the lawn. Should I mow and bag? What options do I have, particularly this spring?
Great to hear! Mowing and bagging in black plastic bags are probably the best idea if you are mowing the knotweed infested area. After you mow, make sure the mower deck doesn't have any living knotweed vegetation stuck in it. Keep the bagged material in the sun for a couple weeks. Check it to make sure it's all dead before composting, etc. In the spring, i would dig out the knotweed sprouts. You won't have much success with herbicide in the spring. You can slice off the roots and rhizome of the knotweed so you don't disturb the lawn too much.
I have had a patch growing for years on the edge of my property, this year I got tired of spraying and took the backhoe of my tractor and dug about 2 foot down over an 8’ wide and 50 foot path, removed what seems like 5 miles of roots and rhizomes. After the digging with the backhoe I screen the soil with a fine tooth pitch fork to sift through and pick out the roots by hand ( only half way done) the plan is to keep the soil soft in that area and rip out by hand whatever survives
That sounds like a very sound approach. Other people who want to adopt this approach just have to be careful like you have been to sort through the excavated soil and pile the rhizomes with as little soil as possible in a location where they can completely dry out. It may be wise cover them with a tarp.
@@GreenShoots thanks for the reply, I figure I’d still have to take a multi year approach, I consider this year year 1, I will excavate and sift what I can, in late summer/early fall I will spray or sponge and in the meantime I’ll pull up what I can by root if I can keep the soil loose. I have worked from the outside edges inward to try to stem the spreading
Hi John--thank you for all this information. We are dealing with huge swaths of knotweed on a property we bought at the end of 2022. Last fall we applied glyphosate to a portion of it, and it was fairly successful. This year we will use your kit and try to hit it twice, and tackle more of it. I know you say not to cut, but it's June 1 and much of it is already over 5 feet tall. By fall, even if we create paths within the swaths, we won't be able to get anywhere near the tops of the plants for foliar spraying. Would it make sense to cut it now just to create shorter plants for fall? They'd be huge again by then, but maybe slightly more manageable for spraying... (Also, I don't think treating the stems is an option for us--there's simply too much. Spraying is probably our only hope.)
Most welcome! For big plots with large knotweed stems coverage is a problem. Many professionals use multi-nozzle extensions for their sprayers to reach above the canopy. But these can expose you to lots of herbicide as you spray down. We are now offering this year for the first time a "conversion kit" for our Large Foam Dispenser that allows the user to spray a stream of liquid herbicide. You can loft the stream high - 12 feet or higher. You then use a sweeping motion to create drops that rain down onto the knotweed (but not on you). This method is fast and effective. It creates very little herbicide drift. If you go to our website, you can order it. Our Guide for a large stand of knotweed discusses this. It's available on our website at "resources" and "knotweed."
We’re up in Maine, been holding tight all summer waiting for flowering to arrive then pass to treat our knotweed. We’re almost there, ready to spray them sometime in the next week with the foamy glyphosate. With rain in the forecast though, should we hold off? If it rains the day after application will that reduce the effectiveness?
Perfect timing! The longer without rain the better. At a minimum you want 6 hours. The target weed can even continue absorbing the herbicide 24 hours after the application. (At least this is what studies on other weeds indicate. The same is probably true with knotweed.) I like to get a couple days at least just to be sure uptake has ceased.
What are good native plants to plant while doing the glyphosate treatments? Would buckwheat survive it ok? I'm in zone 6a GTA, Ontario. Clay, heavy, soil amidst invasive buckthorn. There's also apricot, garlic mustard, Manitoba maple, dog strangling vine, and creeping bell flower... And some plants we want.
i would definitely plant the natives after the 2 major foliar treatments with glyphosate. With the natives in place, you can do followup spot treatments of the knotweed. As to native plants for your area, I would consult local experts. Tell them you want something that is fairly tough.
Great videos, thanks. So, if you knock down a path way to treat the knotweed (large sections like you show in your video) what happens to the 5 feet path ways that you knocked down? I imagine when you go back the 2nd time those pathways will need to be treated? And then the pathways only get one treatment? We have a large area of land that has japanese knotweed (didn't even know what it was until recently). There are other invasive plants/vines/bushes/etc. Would it be better to treat the Japanese knotweed first and leave the other plants until japanese knotweed is controlled? Original thought by the company I contacted was to use a forestry cutter to clear everything out and then wait for knotweed to grow back and apply herbicides but watching your videos and doing other reading I am wondering if that will cause it to spread more and make things worse?
You are most welcome! Thanks for watching. Yes, you will definitely want to treat the paths twice. (You want to treat all the knotweed twice within two weeks or so.) Just treat the paths in a way so you don't box yourself in - walk on a portion of the path and spray the foam on the two sides and then spray that portion of the path as you move along. I would definitely not use a forestry mower to cut the knotweed. It could easily spread the knotweed to other areas that are mowed but don't have knotweed. If there are other invasives where you are treating the knotweed, you could foliar treat them at the same time. Alternatively, if they are too big (taller than 10 feet or so) you could go back in the late fall or winter after the knotweed has died off and treat the invasive vines and woodies with a cut stump treatment.
Hi John, Is it ok to leave the brown canes in a pile after they are treated and cut. By that I mean will they eventually rot etc. Thanks in advance - great video
Yes, absolutely! Just be aware of a couple things. First, it may takes some time for the canes to rot. Second, there could be some risk from spread by seed, although this seems to be minimal with knotweed in North America.
@@GreenShoots Thank you for that, appreciate it. I'm actually in Ireland and have injected the canes last October. I cut them late November and now have the canes on the ground. Should I just bundle them up and leave in a big pile and let them rot?
I have a 3 mature stands I'm trying to eradicate. In early spring after cutting and filling the hollow with herbicide (for the really big thick canes), there has been no major regrowth from the main stand. Any regrowth has been small (less than 1/2 cm in diameter) but also a bunch of the small ones have grown along the fringes. What do I do with these early on during the season? Do I just cut them? Then stop cutting late summer so I can foliage spray? Keep in mind that the majority of my knotweed now is small in diameter. Their leaves are still big. Also, they say cutting can stimulate new growth. Does the same apply to herbicide treatment?
With anything early in the season on the periphery of the stand, I recommend digging the crowns out, moving from the periphery toward the center of the stand. If the stand is small enough and you are game for it, you can even dig out the center of the stand. Then, in mid-summer as you suggest, leave it. Then in the fall, apply herbicide to every knotweed stem you can locate, even the smallest ones. Yes, I do believe any disturbance such as cutting, herbicide treatments, and digging can stimulate new growth. By digging on the periphery, you are "telling" that stand to grow in the center of the stand.
I am trying to get rid of knotweed in backyard which is about 1/4 acre. We took all the dead stalks down in the spring and dug some up to, I have been cutting them back every 2 weeks as they keep growing. Should I not be cutting them back and let them grow and use herbicide in late fall instead?
I have about 1/2 acre, what are your thoughts on burning the dry stalks (in large metal barrels) if I don’t have a place to dispose of them (city ordinances prevent from dumping)
That's a fine way to get rid of the dry stalks. You can also just knock them down and leave them in place on site. I wouldn't move the dead stems (and definitely not green ones). The seeds could potentially be a problem if you moved the dead stems, although not likely a big one. By removing or knocking down the dead aerial shoots, you will be ready for any kind of work you do on the site in late summer or fall.
If anyone has qualms about using herbicides, there are other options for controlling knotweed. They are labor intensive, but, for example, I use mechanical methods myself, primarily as a follow-up to herbicide applications in a previous year. This video of ours describes excavation as a method: th-cam.com/video/k7WgGRiodIc/w-d-xo.html.
We have about 3 Acres of knotweed in southern NH. The house was abandoned for about 15 years and the knotweed spread throughout the property. We have goats and chickens free ranging on the property (and dogs and children!) What are the guidelines for using your product with animals living on the property?
According to the label of the product, you just have to wait until the product dries before humans can re-enter. (I would wait a week just to be sure.) With goats and chickens, since they might ingest the treated plants, I would wait until the knotweed becomes inedible, i.e., once it's dead.
I am buying a home in Maine that has at least an acre of this. Do I have to tackle the entire acre in one season ? And some of it surrounds two lovely full grown weeping willows. If I use the herbicide on the weed around them will it damage the willows?
As suggested in the video, i would knock down the knotweed closest to the willows. When you spray, spray away from the willows. You might also consider trimming back the willows several weeks before you treat the knotweed to limit those areas where foam herbicide could contact the willows. If you want to be extra careful, you could also do cut stem treatments of the knotweed around the willows. Our other video explains that process - more labor intensive but also more precise: th-cam.com/video/tWnLlNRmE5M/w-d-xo.html
@@GreenShoots Thank you for your answer. My concern isn't so much to do with over spray but with the product going into the rhizome and getting into the roots of the willow. I killed a Rhododendron this way when I painted wisteria with round up and the roots were apparently inter tangled with the Rhodo. I am unsure of how much product to buy for an acre of ground too.
@@nevarNJ555 This doesn't typically happen with RoundUp type herbicides, i.e., ones with glyphosate. That's because glyphosate binds tightly with soils, and the roots of unrelated plant species don't transfer the herbicide. It can occur if large amounts of glyphosate are used and especially in sandy soils. The method described in our video doesn't use very much glyphosate. Injections where up to 5 ml of herbicide are injected into each knotweed stem do use a great quantity of glyphosate. That's one reason I don't recommend injections for knotweed.
@@GreenShoots Please don't buy RoundUp. It is too expensive. Support your local farm store. Buy any other brand of the same ingredient as RoundUp, Glyphosate, for half the cost. Just sayin'.
Possibly. However, knotweed evolved in volcanic habitat where it learned to survive pretty intense heat. If a person does not want to use herbicides, I think the most promising method is excavation and pulling the rhizomes early in the growing season before the knotweed clone reestablishes its roots.
@@GreenShoots does glyphosate plus cooking render the stems harmless? If I’m understanding correctly, the stems are still potentially dangerous with just the glyphosate.
To tackle a huge patch, (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.
Thanks for the insightful post! A couple of comments: First, I definitely agree on waiting until the pollinators are finished with the knotweed. Depending on where you are in the country and the weather for a particular year, this time can vary. Just check the knotweed to see whether flowers are open and pollinators are present. Second, I still like doing the treatments at least a couple weeks apart if possible. Some of the knotweed will die which will open up the site. You will be able to see small plants that you missed. I personally don't like to get inside the stand and apply. It is very hard to keep track of where you are and what you have covered. You can also more easily come in contact with the applied herbicide if you are working inside the stand. Finally, one of the benefits of foam herbicide is that you'll get less drift. Especially if you are shooting a mist of herbicide over the top of the knotweed, drift will occur.
@@GreenShoots If you are shooting over the top your nozzle should be wide open, no drift. There's always next year to treat the ones that were missed. Flagging helps to keep track of where you left off. Experience helps but no one is perfect. Can't get 'em all when tackling a giant patch of knotweed. Sometimes it is necessary to create an opening in the canopy to shoot through if the patch is too wide to shoot over top. Always wear a hat inside the clump to keep Knoteed flower droppings out of your hair.
Purchased land last year, after running a field cultivator over it, and planting alfalfa, I now have a huge patch of Japanese Knotweed 🤐💩 Little pieces of roots all over the place
Hi, I want to know would I be able to kill the knotweed if I drill a hole into the stem and pour the poison in? Also how often should I repeat this? Thanks.
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We treated an acre's worth of knotweed last fall. So far, with the exception of tiny shoots cropping here and there, we have not seen any substantial growth. Before spraying, we had spent the entire summer, almost every day, sometimes twice a day, hitting every plant with a scythe. Doing this, we deprived the plant an opportunity to photosynthesize leaves and feed the rhizomes. In one stand of knotweed in adjoining property that we treated,, the entire sprayed knotweed stand is dead with the exception of those few rootballs to the rear of the dense patch that we missed. These had grown to approximately a foot. Our plan with these is to keep them down until October, and re-spray. Lest we think we're just behind, much of the rest of the town has spurious growth going on. So far, so pleased.
That's great to hear! Sounds like you really went after those knotweed. I can think of a couple of advantages to your method: First, by cutting so often, you gave the plant no chance to start storing energy in the rhizomes. It may also be that with so many cuttings, the aerial shoots may not have developed the ability to sprout roots. That could prevent spreading even if the cut aerial shoots contacted moist ground. (Don't know for sure though.) You might also consider digging up the remaining knotweed crowns this spring and early summer. You could have it wiped out by this winter!
@@GreenShoots we will do as you describe. Really impressed with our progress.
as an update, we have had only sporadic growth (the rest of our road has over two feet high growth) of tiny shoots with deformed leaves. These are easily pulled. I have also uprooted any root balls that seem to have no life in them and relinquish their grip quite easily (whereas last summer, they were quite tenacious). Native plants are beginning to naturally encroach. I have also planted buckwheat and spring wheat as a fast cover crop to begin to cover the bare patches of dirt left from the huge knotweed stand we have taken down.
@@pmaher63 Oh hello, I have a knotweed infestation I am trying to get rid of as well. I have a question about your successful method. . As you were so fastidious in cutting down the knotweed in the summer, did the plants eventually flower? My plan was to knock the plants down in June and let them grow and flower and then spray with herbicide in the fall after flowering.. This is because I understand that the optimum time to spray is after flowering. I have knocked down a stand of knot weed in the first half of June and now 2 weeks later I've already got 3 'and even 4 'plants! I am trying to decide if I want to let it grow back, flower and spray or use your method of continuous cutting.
@@robertschoenberg3972 I didn’t let it get tall at all so that it would be easier to treat in the fall. My stand was one acre of an impenetrable thicket of JK.
Most informative. I had read or seen the info about late summer application 2 years ago, and hit our stands in late September, just once, with a very strong mix of glyphosate and a large sprayer, on a calm morning. Unfortunately the sprayer got damaged so it didn't get done last year. But the single application was quite effective last year.
This spring I am seeing a few plants coming up, so will follow the same approach this fall. The largest area is on a near 2 to 1 slope, so I don't know what natives can work there.
If you are replanting a slope, pretty much any native will work there - if there's sufficient sunlight and you can do the work on that slope. It is hard to maintain however. Maybe native shrubs? You can create little planting areas with small retaining walls.
Thanks for this video. I used your tips and applied glyphosate gel (roundup) right before the first frost on a stand of knotweed in my garden. I have not seen a single leaf of knotweed in the year since. Btw this was in Stockholm, Sweden.
Thanks for sharing that, Jens!
promising comment, im currently at war with an infestation of these terrorists!
Okay its second week of September. I have to be patient. Your kit came super fast...thank you!
You are welcome, Rambler Rose! I will pass that compliment on to the people who made that fast delivery happen. Waiting while having to watch an invasive plant grow is tough, I know. But you'll thank yourself for having done so next spring.
@@GreenShoots You are awesome! Thank you for all your help!
Hi John
thanks for very useful videos.
I have learned a lot from you about Japanese knotweed! plant!.
I, have one question for you, I live in Canada and how come I can't buy the (Blu foam agent only). And I am not interested in any Roundup or chemicals just the blue foam agent.
Thank you very much John.
Sorry, we don't sell the Blue Foaming Agent in Canada.
what are these full eradication techniques ya'll are working on? Hoping to hear more soon!
There are some ongoing studies - for example, one at the University of Minnesota being conducted by Alan Smith where they are doing a comprehensive analysis of knotweed control including the use of genetic analysis. These should make a big difference in the coming years.
@@GreenShoots Any update on the U Minn. study "3 years later"?
I'm looking to clear knotweed from the side of a river. Is it safe to use glyphosate via your method with the foam near water?
Yes, just use the aquatic version of glyphosate. Depending on where you live (which state) there may be restrictions on who can apply herbicides near or on water.
Hey there, I've been watching your videos and ordered a glyphosate kit from you. I have 1.43 acres, and probably a full quarter of it (maybe slightly more) is knotweed. The property had been mowed when I bought it so I didn't know about the problem until the land was mine. It is growing in several sections of the property, near my leach field, and just all over the place. A couple of questions:
My neighbors both have it growing on the edges of their property as well. One neighbor is dead set against using glyphosate, so it will still be growing right next to my property. Should I try to push the issue with her a bit more? Because I really would like to try to eradicate it. It seems stupid to just let it keep growing.
Second, is it necessary to dig up all of the rhizomes after you spray and the foliage dies?? I have a LOT of knotweed. I don't know if I'm capable of digging up that much stuff.
In addition to the knotweed growing on the open meadow part of the property, there is a large stand of trees between mine and my other neighbors property. The knotweed is VERY tall and fully growing throughout the stand of trees. Would it be ok to address the stuff on the open areas first, and try next year to get the stuff in the stand of trees?
There are many little flowers that are interspersed in the knotweed, so although currently in Maine, the flowers on the knotweed have gone by, there are still flowers in and around it from other plants, so there are bees still present. Is it ok to wait a bit longer before I spray? I really don't want to kill bees.
Thanks so much for your videos.
With a large stand, the key is deciding where to start. First, based on your description, the leach field is the most pressing. You definitely don't want knotweed invading it because it could damage the perforated pipes. I would create a knotweed free perimeter around the leach field and keep expanding it. Second, to protect desirable plants like wildflowers, you can do spot treatments with precise applications of foam herbicide to the stems of the knotweed near desirable species. On our website under "resources" and "knotweed" you can sign up for our guides. Check out our Knotweed Guide No. 1: How to control a small stand of knotweed. You can apply foam herbicide directly onto the green part of the stems. As described in the Guide apply rings of foam around the stem near the base. If you have the time, you can even rub the stem with a gloved hand to remove dirt and increase the absorption of the herbicide into the green stem and apply just one or two rings of foam herbicide. Third, in terms of timing, you want to make sure your last application is at least a day or so before a killing frost. This is hard to predict, of course, but you can find out first frost dates in your area by searching for the "Farmers Almanac first frost." I recommend two applications spaced about two weeks apart. With the second application, you only apply foam herbicide to the green parts of the knotweed foliage. If the foliage is yellow or a very pale green, it won’t absorb much herbicide. I hope this helps!
@@GreenShoots Thank you so much! So, I should be focused on application on the stems? I was under the impression to do the leaves. There are SO many plants. It's really overwhelming. I can't believe how many there are. But, I agree that protecting the leach field is my priority right now. I really appreciate your videos and advice. Thanks again.
Hey, I’m about to tackle my knotweed invasion. My question is: the plants are alrdy really talk and bushy. Shall I cut them down now so I can treat them more effective in fall? Maybe burn the cut sticks in a big fire pit or shall I just let it grow until fall? It’s alrdy way taller than I am. Thank you in advance.
Also will it damage my Peach tree next to the knotweed with the foam? Really appreciate your knowledge.
I advise against cutting. The plants seem to take up the herbicide better if they are not cut. We now offer a "conversion kit" for our Large Foam Dispenser that allows you to attach a streaming nozzle. This allows you to stream a liquid. This stream can be lofted high and the allowed to rain down on the knotweed. This is better than a spray of liquid or foam for the really tall plants. Professionals use a wand extension but this really isn't feasible for homeowners. Use a more precise method near your peach tree (such as a direct application to the stems). Create a buffer around the peach tree using the more precise method.
one of green shoots videos suggested cutting stalks to 1-10 inches before Fall herbicide application. Which is it cut or no cut? thanks for video
We recommend cutting and treating the cut stems for small infestations. This method is more accurate. However, for large infestations, foliar applications of foam herbicide work the best. The foliar method is both the quickest and most effective. Therefore, if accuracy is not so critical, use the foliar method.
I had a stand bordering a 20 car parking lot - so towering - impractical to park.
Gradually cut to ground level, left foliage to bake on the asphalt. Some smaller root clumps pulled up and dirt shaken off before drying. The dried stuff tossed back into a bare spot. Nothing grew out of that stuff.
The towering plants further back from edge of the lot were injected with small foam applicator, mid-last summer, 2021.
In 2022, the injected did not come back, those closest to the edge remained small
Cars now started parking there.
Tall ones further back, 15 ft, from the edge, were injected, 6 inches above ground level, in October, a few weeks later the entire foliage yellowed. Will see come 2023.
Used a soil knife to cut a Hole in the stem. Have to assume it is over much, but tried to fill the entire cell, 2-4 pumps of the small pump container.
Using your product and it’s great - thanks for the video! The house I purchased has knotweed growing all through the lawn. It was clear cut and the lawn reseeded before I purchased, but predictably the knotweed is growing back already. I need to be able to mow the lawn. Should I mow and bag? What options do I have, particularly this spring?
Great to hear! Mowing and bagging in black plastic bags are probably the best idea if you are mowing the knotweed infested area. After you mow, make sure the mower deck doesn't have any living knotweed vegetation stuck in it. Keep the bagged material in the sun for a couple weeks. Check it to make sure it's all dead before composting, etc. In the spring, i would dig out the knotweed sprouts. You won't have much success with herbicide in the spring. You can slice off the roots and rhizome of the knotweed so you don't disturb the lawn too much.
I have had a patch growing for years on the edge of my property, this year I got tired of spraying and took the backhoe of my tractor and dug about 2 foot down over an 8’ wide and 50 foot path, removed what seems like 5 miles of roots and rhizomes. After the digging with the backhoe I screen the soil with a fine tooth pitch fork to sift through and pick out the roots by hand ( only half way done) the plan is to keep the soil soft in that area and rip out by hand whatever survives
That sounds like a very sound approach. Other people who want to adopt this approach just have to be careful like you have been to sort through the excavated soil and pile the rhizomes with as little soil as possible in a location where they can completely dry out. It may be wise cover them with a tarp.
@@GreenShoots thanks for the reply, I figure I’d still have to take a multi year approach, I consider this year year 1, I will excavate and sift what I can, in late summer/early fall I will spray or sponge and in the meantime I’ll pull up what I can by root if I can keep the soil loose. I have worked from the outside edges inward to try to stem the spreading
Amazing information. If i can't spray (0.5 acre area) in fall, as i will be traveling, is summer a good option? or should i wait for next season?
Thank you! Yes, it would be best if you could treat as late as possible. Try to do it twice as mentioned in the video. Good luck!
Hi John--thank you for all this information. We are dealing with huge swaths of knotweed on a property we bought at the end of 2022. Last fall we applied glyphosate to a portion of it, and it was fairly successful. This year we will use your kit and try to hit it twice, and tackle more of it. I know you say not to cut, but it's June 1 and much of it is already over 5 feet tall. By fall, even if we create paths within the swaths, we won't be able to get anywhere near the tops of the plants for foliar spraying. Would it make sense to cut it now just to create shorter plants for fall? They'd be huge again by then, but maybe slightly more manageable for spraying... (Also, I don't think treating the stems is an option for us--there's simply too much. Spraying is probably our only hope.)
Most welcome! For big plots with large knotweed stems coverage is a problem. Many professionals use multi-nozzle extensions for their sprayers to reach above the canopy. But these can expose you to lots of herbicide as you spray down. We are now offering this year for the first time a "conversion kit" for our Large Foam Dispenser that allows the user to spray a stream of liquid herbicide. You can loft the stream high - 12 feet or higher. You then use a sweeping motion to create drops that rain down onto the knotweed (but not on you). This method is fast and effective. It creates very little herbicide drift. If you go to our website, you can order it. Our Guide for a large stand of knotweed discusses this. It's available on our website at "resources" and "knotweed."
@@GreenShoots Thank you! If I use the conversion kit, do I still use the foaming agent?
We’re up in Maine, been holding tight all summer waiting for flowering to arrive then pass to treat our knotweed. We’re almost there, ready to spray them sometime in the next week with the foamy glyphosate.
With rain in the forecast though, should we hold off? If it rains the day after application will that reduce the effectiveness?
Perfect timing! The longer without rain the better. At a minimum you want 6 hours. The target weed can even continue absorbing the herbicide 24 hours after the application. (At least this is what studies on other weeds indicate. The same is probably true with knotweed.) I like to get a couple days at least just to be sure uptake has ceased.
What are good native plants to plant while doing the glyphosate treatments? Would buckwheat survive it ok?
I'm in zone 6a GTA, Ontario. Clay, heavy, soil amidst invasive buckthorn. There's also apricot, garlic mustard, Manitoba maple, dog strangling vine, and creeping bell flower... And some plants we want.
i would definitely plant the natives after the 2 major foliar treatments with glyphosate. With the natives in place, you can do followup spot treatments of the knotweed. As to native plants for your area, I would consult local experts. Tell them you want something that is fairly tough.
Great videos, thanks. So, if you knock down a path way to treat the knotweed (large sections like you show in your video) what happens to the 5 feet path ways that you knocked down? I imagine when you go back the 2nd time those pathways will need to be treated? And then the pathways only get one treatment? We have a large area of land that has japanese knotweed (didn't even know what it was until recently). There are other invasive plants/vines/bushes/etc. Would it be better to treat the Japanese knotweed first and leave the other plants until japanese knotweed is controlled? Original thought by the company I contacted was to use a forestry cutter to clear everything out and then wait for knotweed to grow back and apply herbicides but watching your videos and doing other reading I am wondering if that will cause it to spread more and make things worse?
You are most welcome! Thanks for watching. Yes, you will definitely want to treat the paths twice. (You want to treat all the knotweed twice within two weeks or so.) Just treat the paths in a way so you don't box yourself in - walk on a portion of the path and spray the foam on the two sides and then spray that portion of the path as you move along. I would definitely not use a forestry mower to cut the knotweed. It could easily spread the knotweed to other areas that are mowed but don't have knotweed. If there are other invasives where you are treating the knotweed, you could foliar treat them at the same time. Alternatively, if they are too big (taller than 10 feet or so) you could go back in the late fall or winter after the knotweed has died off and treat the invasive vines and woodies with a cut stump treatment.
Hi John, Is it ok to leave the brown canes in a pile after they are treated and cut. By that I mean will they eventually rot etc. Thanks in advance - great video
Yes, absolutely! Just be aware of a couple things. First, it may takes some time for the canes to rot. Second, there could be some risk from spread by seed, although this seems to be minimal with knotweed in North America.
@@GreenShoots Thank you for that, appreciate it. I'm actually in Ireland and have injected the canes last October. I cut them late November and now have the canes on the ground. Should I just bundle them up and leave in a big pile and let them rot?
I have a 3 mature stands I'm trying to eradicate.
In early spring after cutting and filling the hollow with herbicide (for the really big thick canes), there has been no major regrowth from the main stand. Any regrowth has been small (less than 1/2 cm in diameter) but also a bunch of the small ones have grown along the fringes. What do I do with these early on during the season? Do I just cut them? Then stop cutting late summer so I can foliage spray? Keep in mind that the majority of my knotweed now is small in diameter. Their leaves are still big. Also, they say cutting can stimulate new growth. Does the same apply to herbicide treatment?
With anything early in the season on the periphery of the stand, I recommend digging the crowns out, moving from the periphery toward the center of the stand. If the stand is small enough and you are game for it, you can even dig out the center of the stand. Then, in mid-summer as you suggest, leave it. Then in the fall, apply herbicide to every knotweed stem you can locate, even the smallest ones. Yes, I do believe any disturbance such as cutting, herbicide treatments, and digging can stimulate new growth. By digging on the periphery, you are "telling" that stand to grow in the center of the stand.
Thanks a lot sir!
you are most welcome!
I am trying to get rid of knotweed in backyard which is about 1/4 acre. We took all the dead stalks down in the spring and dug some up to, I have been cutting them back every 2 weeks as they keep growing. Should I not be cutting them back and let them grow and use herbicide in late fall instead?
I recommend stop cutting them back and let them grow. Then, as you mention, apply herbicide in the fall.
Thank you! I will stop wasting my time cutting them down :(
I have about 1/2 acre, what are your thoughts on burning the dry stalks (in large metal barrels) if I don’t have a place to dispose of them (city ordinances prevent from dumping)
That's a fine way to get rid of the dry stalks. You can also just knock them down and leave them in place on site. I wouldn't move the dead stems (and definitely not green ones). The seeds could potentially be a problem if you moved the dead stems, although not likely a big one. By removing or knocking down the dead aerial shoots, you will be ready for any kind of work you do on the site in late summer or fall.
How toxic is glyphosate? My wife is very scared to use this on our yard, we have 2 young boys. Are there any less toxic options?
If anyone has qualms about using herbicides, there are other options for controlling knotweed. They are labor intensive, but, for example, I use mechanical methods myself, primarily as a follow-up to herbicide applications in a previous year. This video of ours describes excavation as a method: th-cam.com/video/k7WgGRiodIc/w-d-xo.html.
We have about 3 Acres of knotweed in southern NH. The house was abandoned for about 15 years and the knotweed spread throughout the property. We have goats and chickens free ranging on the property (and dogs and children!) What are the guidelines for using your product with animals living on the property?
According to the label of the product, you just have to wait until the product dries before humans can re-enter. (I would wait a week just to be sure.) With goats and chickens, since they might ingest the treated plants, I would wait until the knotweed becomes inedible, i.e., once it's dead.
I am buying a home in Maine that has at least an acre of this. Do I have to tackle the entire acre in one season ? And some of it surrounds two lovely full grown weeping willows. If I use the herbicide on the weed around them will it damage the willows?
As suggested in the video, i would knock down the knotweed closest to the willows. When you spray, spray away from the willows. You might also consider trimming back the willows several weeks before you treat the knotweed to limit those areas where foam herbicide could contact the willows. If you want to be extra careful, you could also do cut stem treatments of the knotweed around the willows. Our other video explains that process - more labor intensive but also more precise: th-cam.com/video/tWnLlNRmE5M/w-d-xo.html
@@GreenShoots Thank you for your answer. My concern isn't so much to do with over spray but with the product going into the rhizome and getting into the roots of the willow. I killed a Rhododendron this way when I painted wisteria with round up and the roots were apparently inter tangled with the Rhodo. I am unsure of how much product to buy for an acre of ground too.
@@nevarNJ555 This doesn't typically happen with RoundUp type herbicides, i.e., ones with glyphosate. That's because glyphosate binds tightly with soils, and the roots of unrelated plant species don't transfer the herbicide. It can occur if large amounts of glyphosate are used and especially in sandy soils. The method described in our video doesn't use very much glyphosate. Injections where up to 5 ml of herbicide are injected into each knotweed stem do use a great quantity of glyphosate. That's one reason I don't recommend injections for knotweed.
@@GreenShoots Please don't buy RoundUp. It is too expensive. Support your local farm store. Buy any other brand of the same ingredient as RoundUp, Glyphosate, for half the cost. Just sayin'.
Would a weed burner cook the stems enough to render them harmless?
Possibly. However, knotweed evolved in volcanic habitat where it learned to survive pretty intense heat. If a person does not want to use herbicides, I think the most promising method is excavation and pulling the rhizomes early in the growing season before the knotweed clone reestablishes its roots.
@@GreenShoots does glyphosate plus cooking render the stems harmless? If I’m understanding correctly, the stems are still potentially dangerous with just the glyphosate.
To tackle a huge patch, (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.
Thanks for the insightful post! A couple of comments: First, I definitely agree on waiting until the pollinators are finished with the knotweed. Depending on where you are in the country and the weather for a particular year, this time can vary. Just check the knotweed to see whether flowers are open and pollinators are present. Second, I still like doing the treatments at least a couple weeks apart if possible. Some of the knotweed will die which will open up the site. You will be able to see small plants that you missed. I personally don't like to get inside the stand and apply. It is very hard to keep track of where you are and what you have covered. You can also more easily come in contact with the applied herbicide if you are working inside the stand. Finally, one of the benefits of foam herbicide is that you'll get less drift. Especially if you are shooting a mist of herbicide over the top of the knotweed, drift will occur.
@@GreenShoots If you are shooting over the top your nozzle should be wide open, no drift. There's always next year to treat the ones that were missed. Flagging helps to keep track of where you left off. Experience helps but no one is perfect. Can't get 'em all when tackling a giant patch of knotweed. Sometimes it is necessary to create an opening in the canopy to shoot through if the patch is too wide to shoot over top. Always wear a hat inside the clump to keep Knoteed flower droppings out of your hair.
Purchased land last year, after running a field cultivator over it, and planting alfalfa, I now have a huge patch of Japanese Knotweed 🤐💩
Little pieces of roots all over the place
Ugh. I would definitely try to treat it this fall before those plants have the opportunity to establish themselves.
Hi, I want to know would I be able to kill the knotweed if I drill a hole into the stem and pour the poison in? Also how often should I repeat this? Thanks.
Yes, you can use an injection method. It is slow and uses more herbicide than I like to use. Consider getting a hypodermic needle.
No expert recommends mowing!
You are absolutely right. This video doesn't in any way recommend mowing.
thank you for your knowl3dge in helping our battles and struggles with this invasive super demon
You are most welcome!