japanese knotweed

Hi all!

what a great forum this is.

I'm looking for some expert advice as i have moved into a house with a large plot of land.

My main concern is that i have a large section that is infested with the japanese knotweed. I guess it spans over 200 sq/m. It's on a slope which leads down to a brook.

I'm hoping to use the space for more lawn and a vegetable patch.

I've searched and have found some useful information, but hope i can seek some advice from others who may have experience at this problem.

I'm a bit wary on roundup as it may damage the wildlife thats surrounding.

TIA!

 

You have my sympathy Chevy

As we're in the winter now, Roundup wouldn't help you very much at the moment anyway, although I'm afraid you'll probably have to resort to it next year (more on that later). For now I'd concentrate on getting rid of as much surface growth as you can, because the plant will be pretty dormant from now until spring - removing the surface growth will allow you to get to the fresh growth when it starts sprouting again.

On that sort of sized area, I would really recommend getting a 3-6 tonne digger in, the bigger the better. Obviously cost is a factor, but when you've tried removing it by hand, you'll soon be willing to part with the money. The advantage of a digger is that it will rip out a lot of the root growth as well, meaning you have less live plant to worry about in the spring. If you do go down this route, get a professional driver in, and agree up front that he is responsible for any damage to hydraulic pipes or shattered glass on his digger, because Knotweed is a nightmare for damaging machinery.

The other option it to take to it with a chainsaw, but quite frankly, its like trying to cut through a Mangrove Swamp, and you'll trip all over the place, which is not a good thing with a chainsaw in your hands. You're also quite likely to throw the chain a good few times, which is potentially dangerous / expensive. Wear safety gear

This is very important - you need to dispose of the waste in such a way that it cannot spread. It is a criminal offence to knowingly assist the spread of Knotweed, so the best thing is to burn it on site. There's plenty on the net about this, but just don't spread it, because it's already spreading faster than it can be removed, so it won't make you very popular, and could result in a hefty fine.

Now for the good news. Once you've got rid of the surface growth, its a case of beating down any new growth, and ultimately wearing out the root system. You could do this with a strimmer, but you're likely to simply spread the vegetative matter, giving it the chance to regrow.

This is where Roundup works. You can either spray any new growth with Roundup, or pour a "strong" mix into freshly cut stems that were severed about 3 inches from the ground. Generally people recommend pouring it neat into the stems, but I'd argue that diluting it to the maximum label recommended concentration not only keeps you within the bounds of the manufacturers liability, but also helps move it around the root system. Either way, I wouldn't go over what the manufacturer recommends.

Two points here - one, Roundup is about as safe a chemical as you can get, so used correctly it won't damage water courses or your local environment; other people will no doubt have their own opinions on this, but JK is one of those things where only a chemical will do, and being namby pamby about it could mean that you end up putting down more chemical over the long term that you would have if you'd done it properly the first time. The second point is be sure to use commercial strength Roundup - it's both cheaper and more effective that what you can but in the garden centre, but you may need to get someone in to apply it (from memory, I think you could do it yourself, but check anyway).

OK, best guesses are that it takes up to 3 years of a sustained Roundup application programme to eradicate a stand. I've found it can happen sooner than that, but you ahould be prepared. I suppose if you were really anti the chemical route, you could just religiously remove the surface growth by hand - either way the plant will die out eventually, but if you give it half a chance to recolonise it'll take it.

Just before you die of boredom, there's a couple of other things you might want to bear in mind. The first one is to beware of contractors pricing for the work, because JK made a lot of people a lot of money, largely due to the fact that it was / is portayed as a sort of modern day triffid. But you should also balance that against what I've said above, and not expect it to be a cheap or easy thing to get rid of. The best advice I could give is to treat it as a work in progress, always assess the necessity of additional work or treatments if you decide to use a professional. I don't deal with that side of things any more, but I'd gladly give you my opinions on any quotes you get - if you decide to go down that route.

And finally, because all bad things have some good about them, it's worth pointing out that in the British Isles, JK is the largest female species in the world, as all the vegetative matter in this country stems from one female plant. Why is that good? Well, before the arrival of JK, my mother in law held that dubious honour...

 

Hi there and welcome - Japanese knotweed is a pernicious weed. Have you considered whether it would be worth the investment to get it professionally removed - either your council or garden centre for advise. As I recall it is not the easiest thing to remove - but I don't know the best method.

 

would sodium chlorate help at all,,,,, its a lot cheaper and it sounds as tho the area is lost to cultivation for a while anyways,,,,,,,,,,,, not to be used on the lower slope where it might get in to watercourse,

 

i used a professional hedge trimmer but i think if i were you id invest in a machete or a slasher, it is essentila to keep topgrowth down,
i d get a big azada and a chrome to keep diggin out the roots too, this should keep you warm all winter!
sounds like a nightmare...... ive got about 50 sq in a bit of wasteland

 

Thank you all so much for your advice!

Thats a lot of useful information Will. I liked the idea of using a big digger as i want the area landscaped. The only problem i can think of is the slope as it is quite steep. But i will treat the area with roundup as it seems safe. I'm a keen fisherman so don't want to harm the water or any wildlife.

I'm also interested in Frans idea, i spoke to my council but the person i need isn't in today.

I'll take a photo tomorrow and post it up.

Thanks again all!

 

here are some pictures of my infected area.






It seems that i have JK growing in little parts round my garden. Think i will try treating these areas myself.

Still waiting for news from my council.

 

Couple of sites that may be of interest:

Cornwall Knotweed Forum
RHS Advice: Japanese Knotweed

Good luck!

 

It looks as if you're in for a hard time looking at the size of your garden Chewy. If you're young, strong and healthy then you should be able to face the challenge with enthusiasm. Good luck!

 

Im young strong and brimming with enthusiasm

I have just spoken to my local council, they say they don't offer a service. But what they usually do is treat the area with round up pro. And that it should not effect the brook at the bottom of my garden.

As i don't want to disturb the roots i will try using round up for the coming year and see what the results are like.

Does anyone know where i can get round up pro in bulk? As i think i will need lots of it.

 

Nice pad Chewy!

Couple of links for people who will supply you with Roundup Pro Biactive:

Sherriff Amenity
Rigby Taylor

Both these companies deal nationwide, so don't worry about location. You can buy 5 or 10 lt containers, and you ought to be pleasantly surprised at the cost,

Good luck

 

Sorry the council could do no more than offer advise - but twas worth a go. You sure have got a big job on your hands - but massive satisfaction - when done. The best of luck with it