Japanese Knotweed, correct weed killer?

PrenticeBoyofDerry · 3 Jun 2011

I understand a weed killer containing glyphosate should be used when trying tho eradicate Japanese Knotweed, most weed killers do have this in.
Through research roundup seems to be the best big brand name that contains glyphosate but I don't think the potency is enough, would it be worth buying powered form and diluting so it is more concentrated?
If so what is the best product to buy?

merlin50 · 3 Jun 2011

The young, Spring shoots can be cooked and eaten, they have a mild rhubarb flavour

mctav · 3 Jun 2011

I dug out all the plants and any obvious roots of an infestation i had a couple of years back, roundup works perfectly on any new shoots that pop up.

PrenticeBoyofDerry · 3 Jun 2011

merlin50 said:
The young, Spring shoots can be cooked and eaten, they have a mild rhubarb flavour

So you are suggesting the best way to eradicate them is in a crumble?

mctav said:
I dug out all the plants and any obvious roots of an infestation i had a couple of years back, roundup works perfectly on any new shoots that pop up.

The shoots are quite new the second lot since March/April, I have sprayed them with round up about two/three days ago but seems to had little or no effect, they are not withering or turning brown, still look quite healthy.
Can you buy powered roundup, so I can make a more concentrated solution?

RedHerring2 · 3 Jun 2011

plenty of info' here:
http://www.dgsgardening.btinternet.co.uk/japknot.htm

PrenticeBoyofDerry · 3 Jun 2011

RedHerring2 said:
plenty of info' here:
http://www.dgsgardening.btinternet.co.uk/japknot.htm[/QUOTE]
Looks like that's where the crumble idea comes from!
Sounds like you wait until late summer to treat them, but there a pain in the arse, strangling my shrubs!

mctav · 3 Jun 2011

Are you putting enough on?....i give the new growth a good soak all over, it kills them dead in a couple of days.

You can get concentrated Roundup thats meant to be diluted but i suppose some of this undiluted would be worth a try?.

r896neo · 3 Jun 2011

It is one of the most invasive hard to kill weeds and as such doesn't respond that well to normal weedkillers like round-up. There are professional grade weedkillers like tordon which will be very effective but you need a spraying license to get it.

Try bruising (stamping all over it) before spraying.

PrenticeBoyofDerry · 4 Jun 2011

I gave it a fair old soaking but had to be careful in some areas due to other plant life.
I have seen some powered glyphosate sachets, might give them a go.

But stamping all over it could cause the stuff to germinate elsewhere, I thought you had to be very careful not to cause contamination.

r896neo · 4 Jun 2011

You won't spread it by stamping on it. Sending pieces of it flying is a big no no, for example if you tried cutting it with a strimmer, but stamping and bruising will help the uptake of the weedkiller.

You may be able to buy tordon online somewhere without a PA1/PA6

PrenticeBoyofDerry · 4 Jun 2011

Just done a bit of tordon googling, it's not keep stuff and the sites I visited seem to be quite strict on who they sell it to.
I wonder if I could tap some of a lad at the council?
I read you can cut the brown stems and inject them, but the ones I have are quite young, leafy and green.

r896neo · 4 Jun 2011

Your other problem will be the expense, as you can'ty really buy it in small quantities

mctav · 5 Jun 2011

How bad is your problem?.....what size does the knotweed cover?. Like I mentioned earlier, I had an infestation of the stuff over a 15 square metre down an unused strip of land next to my house and it was coming up through my patio.
Its taken three years to virtually eradicate the stuff, an odd stem comes through but a blast with Roundup or dig it out by the roots does the trick.

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Japanese Knotweed, correct weed killer?

merlin50

RedHerring2

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