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The East Dulwich Forum
The Bishop, The EDT, The Great Exhibition, the Actress or another?
messageJapanese Knotweed
Posted by rosa123 October 01, 04:57PM

Hi, I live in a block of flats (36 flats in the building) and we have a communal garden. We think we have spotted Japanese knotweed on the garden, but would like confirmation before we look into the eye-watering cost of removal. Can anyone help? Does anyone have any experience of this/local removal firms? Thanks.

messageRe: Japanese Knotweed
Posted by nxjen October 01, 05:28PM

If you’re in Southwark, the council will help.

[www.southwark.gov.uk]

messageRe: Japanese Knotweed
Posted by fishbiscuits October 01, 06:19PM

If it's in your own garden, tackle it yourself with glyphosate. It is doable if you are persistent.

The only reason (that I can see) to get one of these companies in is that you can pay a fixed price for complete eradication with an n year guarantee, to keep potential buyers happy.

messageRe: Japanese Knotweed
Posted by micromacromonkey October 02, 08:16AM

eat it?

[environetuk.com]

messageRe: Japanese Knotweed
Posted by Penguin68 October 02, 09:31AM

It does take several seasons with glyphosate to completely eradicate the weed, but it does work - assiduously spraying as soon as it leafs up in the spring and regularly repeating the dose will do it. The commercial eradicators will also often dig up the weeds roots as much as they can. This is a big job. The weed is very vigorous and should only be burnt if it is being disposed of. Because the stem is hollow but segmented (like a bamboo) cutting it and directly apply glyphosate into the stem will not work - you must drench the leaves.

The commercial removal route is preferable if you are aiming to sell the property quickly - as mortgage companies hate it. In fact the weed is not as damaging to the built environment as was first thought/ feared (it will not undermine and bring down walls etc.) - but mortgage companies, like insurers, take the precautionary principle to ridiculous lengths. If you see it growing 'in the wild' (it was quite common in e.g. Camberwell Old Cemetery) it's actually quite pretty, especially in flower.

messageRe: Japanese Knotweed
Posted by Ginster October 02, 02:34PM

Had this when I was selling (I had no idea what it was, mortgage survey found it). Even though it was 60ft from the house in the garden the buyers had to get a new mortgage so reduced their purchase price. I also had to pay for a company to remove it (luckily split with next door as turned out they had it too). The bonus with using them is they offer a 5 year guarantee.

messageRe: Japanese Knotweed
Posted by fishbiscuits October 02, 03:08PM

Penguin68 Wrote:
-------------------------------------------------------
> Because the stem is hollow but segmented (like a bamboo)
> cutting it and directly apply glyphosate into the
> stem will not work - you must drench the leaves.

Stem filling can work very well... I know from experience... but you have to either make the cut at near ground level, or completely cut off the top and break up the internal structure with a long rod of some description.

But yes, regularly drenching the leaves with a concentrated glyphosate preparation does work too.

messageRe: Japanese Knotweed
Posted by Angelina October 02, 04:53PM

Cutting the stem and breaking the lining is most effective, then spraying the small leaves that grow.

Digging roots up is a good idea, but if you drop even a tiny bit it will grow so it's better to kill it than dig it

messageRe: Japanese Knotweed
Posted by Ginster October 02, 05:27PM

For any DIY don't forget you have to dispose of it in a specific way (think it's actually illegal not to. Not that anyone knows that!)

messageRe: Japanese Knotweed
Posted by belladonna October 02, 06:21PM

I have some in the back garden, was appalled when i first realised. But we applied the poison down the cut off stem. It's less vigorous now. (the council offered to do it for a few thousand!) I don't really think it is to be feared as much as I thought. However my neighbour has a knotweed garden, and insisted on digging it up and wondering why it came back. I have heard that burning can work.

messageRe: Japanese Knotweed
Posted by Dark Knight October 18, 02:16AM

Glycophosphate (aka glyphosphate / Roundup) inhibits an enzyme essential to plant growth. It is not very effective against Japanese Knotweed's underground rhizomes but will kill foliage thus starving the rhizomes over time.

An environmentally friendlier herbicide that kills foliage on contact is 15-20% vinegar solution (handle with care), which is non-toxic, fully bio-degradable and causes no river/water-table pollution or human/animal health concerns.

Recent research by Swansea University into knotweed extermination can be accessed from this page near the bottom:
Swansea University scientists lead the way in tackling Japanese knotweed
or directly at:
Optimising physiochemical control of invasive Japanese knotweed

messageRe: Japanese Knotweed
Posted by B&G October 18, 07:58AM

We tried to buy a house with knotweed in the garden and was told by the surveyor “I would not buy this house at any cost”. Probably overkill, but it put us off and I imagine it will put others off too. I’d definitely start to get rid of it. It is absolutely illegal to dispose of it in anything other than very controlled circumstances so don’t put it in your brown bin!

Good luck getting rid, you can definitely tackle it alone with the help of your neighbours and the right product.

messageRe: Japanese Knotweed
Posted by ed26 October 18, 01:49PM

Or at least don't put it in your brown bin and shout "Hey everyone, I've just put a load of Japanese Knotweed in my brown bin."

Or you might find someone who lives in a rented property who will be happy to put it on their compost heap.


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