If you already know your conclusions before you do the research, then you’re doing science wrong.
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Himalayan blackberry is a pussycat in comparison actually. Plus they’re tasty! Invest in a mattock. First cut the entire plant down to short stubs, then dig and pry the entire root out. Every damn bit. Good luck doing that with knotweed. You’ll soon know if you missed some but you can go back and finish it off. Satisfying.
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There’s apparently some evidence that UK insects are slowly adapting to eat knotweed. I hope that releasing these bugs is a success - and I hope they don’t find something native tastier!
#iamabotanist, and I do have some 5 years experience fighting Fallopia × bohemica in a garden where I lived. I moved, without having won completely, but it was clear that continued care would have rooted out the bastard.
My message, @beschizza, is: it will be a long fight, but depending on how large your garden is and how much effort you can allow to flow this way, it can be done.
To get one thing straight: these plants have a rhizome. You’re not fighting it’s roots, you’re fighting it’s rhizome. It lives underground. It talks with it’s hands… Oh, sorry, don’t know what triggered that. I’ll try again.
It has a rhizome. Even small parts of this rhizome can resprout. Hacking it to pieces is just like making cuttings. (Tribbles, all teh way down!) Killing a whole stand means killing the rhizome, or completely removing it. A mixture of methods can help decimating Fallopia, but only long-term efforts are effective if you don’t want to go industrial scale and just dig out the whole fucking stand at least 60 cm deep and dispose the soil in a professional large-scale composter (reaching enough temperature to kill it, without fire) or a special steam treatment (yes, they do exist, for sterilising large amounts of soil).
I will quickly describe what happend in my garden:
The year I moved in, someone treated the whole fucking front yard with glyphosate. Everything seemed dead. I could see the rotting stalks of Fallopia and knew this would not prove effective.
So, mid-November, after receiving a very enraging review of one of my papers, I took that negative energy to the front yard with a pickaxe and a spade. I dug the whole thing, and tried to collect every bit of rhizome I could find. I did not sieve the soil, since I don’t own one of these:
(Seriously, get one of those, and don’t dig in the wettest time of the year. It helps.)
Afterwards, i.e. after the soil had settled and tilth had improved, I planted stuff. In my case, I chose, among others, woodruff, geranium and other ground cover. Everything which could compete at the site in question with the bastard is good.
The bastard, of course, came back. I controlled the area about monthly and tried to get the rhizomes, if possible, using some weeding device like this:
If I could not pull out the rhizome, I used a syringe with some glyphosate leftovers I found on the premises and filled the hollow stalks directly above or even below ground with it. Just a bit, usually below 2 ml.
I did that for three years and each year less new shoots were found. When I wasn’t so thorough the fourth year, and neglected my monthly control, it already looked as if the bastard would be alive enough to make a comeback. Because I was curious and some idiot gardeners employed by my landlord mowed my ground cover, I dug at every shoot for the rhizome that autumn, and again hand-collected them for destruction. The fifth year looked quite alright, and I pulled out some more rhizomes, which looked really weak and not at all alive-and-kickin’, but more like Voldemort in that Matrix whiteroom scene under the bench.
I am of the opinion that, given another three or four years, I would have weeded out the Fallopia bastard. However, #iamabotanist, and hence I doubt I ever have a ‘normal’ life, staying at one place for more than a couple of years.
That’s my story. Rob, don’t let anyone berate you for using glyphosate. Applied locally, into the stalks, of even injected in the rhizomes (which is nearly impossible, I tried!) it is effective and less dangerous than other pesticides. Considering the effect knotweed has when it spreads, the risks are outweighed.
The method brought forth above covering the site with black plastic will likely work as well to reduce the infestation. From all I have seen so far, I doubt it will be completely effective, so monthly control afterwards would not only be prudent in my book, but a must. Don’t underestimate the fucker.
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Ooooooh, now my interest is piqued. (Although some quick google-fu tells me there are only isolated pockets in my area. I should be glad, I suppose.)
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Here in DC area, it’s invasive, you see it a lot by the roadside. Not as bad as knotweed.
"There are no known biological controls for bamboo, unless you count the Giant panda. "
http://mdinvasives.org/iotm/jan-2011/
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I bet Dr Dan Jones would be overjoyed if he was wrong about there not being a a silver bullet for an invasive species.
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I strongly suspect the type on my family’s property was the clumping type mentioned in that article, which might explain why it didn’t really spread.
We had a well established infestation in our garden in France when we bought the property (as did our neighbours). We (and our managers, it’s a rental) did a thorough and extensive programme over about 4 years of pulling young shoots out or cutting the more mature sprouts at ground level, inserting a screwdriver to break the valves as deep as possible then filling the stem with a somewhat over strength glyphosphate mix.
After 3 years we were mostly clear and the neighbour’s garden infestation looked rather sickly.
After 4 years we were clear, more or less with just the occasional invasion from other established stands nearby.
The neighbour is also clear.
…
It can be done.
Also, noticeably (we are in the French Alps) - something is definitely eating the leaves. There are apparently trials of importing the particular Japanese beetle that eats only knotweed into England…
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Tming is one of the most important aspects of control. You will have the best success by waiting till later in the summer when the plant is flowering. It will be at its most vulnerable, having put all its energy into reproduction. Foliar spray with glyphosate at the rate specified on the label. (One of the most important decisons to make is the amount of active ingredient in the liquid you are applying. COTS lawn spray is ~2%, brush control is ~25%, and commercial uncut is ~50%.) This process will likely need to be repeated over several years for a serious infestation.
Actual scientists have developed methods for controlling many invasive plants and you can find their reccomendations here:
https://wric.ucdavis.edu/
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Here’s what one research project found
When designing management strategies, effective control of F. japonica may be achieved by biannual (summer and autumn) foliar glyphosate applications at 2.16 kg AE ha−1, or by annual application of glyphosate in autumn using stem injection at 65.00 kg AE ha−1 or foliar spray at 3.60 kg AE ha−1. Addition of other herbicides or physical treatment methods does not improve control. This work demonstrates that considering phenology, resource allocation and rhizome source–sink relationships is critical for the control of invasive, rhizome forming species.
The article includes a handy graphic of the knotweed life cycle
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I’d say the tartness is less lemony than apple-y, and distinctly grassier than rhubarb. I recommend it for ice cream.
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Amusing and interesting article about knotweed on slate.
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You have to keep going back after the roots. Relentlessly. Over and over again. And again. If you keep on doing that, eventually you can eliminate the Japanese knotweed.
I’ve had the same problem with mint.
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Sure, in terms of stubbornness, but dealing with blackberry is going to leave you bleeding unless you use goats. It also doesn’t respect fences or property lines, and is easily spread by birds.
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I was already wondering if digging it up and creating a charcoal mound kiln on the spot would be a viable option…
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Really! I was admiring that bamboo when I was out in DC some weeks back. I thought it was native, since there are native Bamboo species in the Americas. (Just less than there used to be)
O man, when I lived in Brooklyn our yard was full of this stuff, growing 8-10 feet high every summer, turning into a dry brown fire hazard in the fall, dying back in the snow & then re-sprouting again in spring. My research showed that it could reproduce a full plant from any part of the plant, even a fragment of leaf or stem. I’m not sure even sheetmulching with plastic would stop it but it might be worth a try.
We spent an incredibly hot day hacking it down with machetes & stuffing it into bags. That afternoon the power went out & all the neighbors came outside. They thought we were crazy to even try. And sure enough, it all grew back in a year or so.
I never tried eating it but I did find some indication that it’s used in Chinese herbal medicine…maybe you could find a practitioner interested in harvesting. Or try to find a biodynamic gardener who might suggest a solution.
Glyphosate destroys pollinators & stays in the soil so, yeah, not recommended. I too read that you would have to inject directly into the root system – hard to do while wearing the correct protective gear – & if it’s true that the whole system is one, it’s unlikely that would work unless you injected every single stem.
It really is an amazing plant…maybe you should just build a tea hut under it & be thankful for the shade & greenness. Or try to make contact with its ruling deva & ask it respectfully to leave. This is desperate experience talking.
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Third word = of?
