Topic: Knotweed

[reedos]

Hello all - this is my first post, although I've read loads. I have two allotments, one I've had for two years and after a lot of clearing is doing quite nicely, the other for a year and this is where my problem lies. Quite simply I have Japanese Knotweed encroaching from council land. Has anybody else had this and how do you get rid of it ? The stuff I've read on the site is quite contradictory some say spray in Spring, some in Autumn, some say dig, some say don't dig. What do you do ?

Also read it was a notifyable weed - so tried to tell the Parks Dep't of the council who claimed not to know what I was on about.

Please help.

Andy

[gavin]

Hi reedos - you've maybe found these already; if so, sorry!

http://www.environment-agency.gov.uk/netregs/processes/367836/?lang=_e - have the council have used flails or rotovators?  Comes under the rubric of "to plant or otherwise encourage" - hmm, chance for a bit of judicial blackmail?  Can't guarantee it'll work - our local council panicked and made lots of promises (and guess what? Did ....-all!)

http://www.ex.ac.uk/knotweed/
http://www.cabi-bioscience.org/html/japanese_knotweed_alliance.htm

Spraying doesn't work, afaik.

Somewhere I read about the National Trust (?) experimenting with injecting glyphosphate deep into the stalks - but I can't find the reference; from memory, it required large amounts and very specific limitations (time, season, number of applications?).

Our local council allotment officer recommended keeping it cut very short - the whole stand, not just part of it - for 2-3 years.  It starves the roots out eventually - but the whole area does need to be cut, regularly, over the period.

Nasty stuff - and the council expect you to pay your rent?  Wonders will never cease!

All best - Gavin  

[micsmum]

Apparently it has been found on one of the Guildford allotment sites - thankfully not ours - yet.
Helen

[Steven]

Despite what the council have told you-they are legally obliged to clear it (probably more so on a lottie).If your council play dumb-report them to the enviromental agency.

If you decide to have a bash at removing it yourself-remember,you cannot by law dispose of it in landfill.The only way of destroying cut vegetation is by burning it.Apparently some success has been found using roundup,but needs many many applications.

Good luck!

[djbrenton]

I'd also do what an old timer told me he did which successfully got rid of mares tail eventually. He dug a 3 foot deep trench along his border and lined it with metal sheet. Sounds drastic, but if it's going to creep back from next door then you're fighting a losing battle otherwise.

[Garden Manager]

Cant it be dug out? Surely if you are thorough and carefull and get al the roots then that will get rid of it? (might take a few 'goes' though). If weedkiller is ineffective surely this is the way to go.

[gavin]

Depends how far, how deep, and how "clinically" you want to/are able to dig?  I was looking at a school playing field this week - a small clump of JK around a telegraph pole inaccessible to the tractor mower, and shoots are coming up 20, 30, 50 feet away.

Nasty stuff - I can't imagine that digging it would get rid of it. 

Rigourous and repeated cutting of ANY young shoot that dares show its face - that'll work, but it takes time, I'm told.

All best - Gavin

[reedos]

Thanks everyone for the advice - the allotment secretary has got in touch with the council again - and he reckons they've already been round to sort the stuff growing outside my lottie. I'm not actually convinced but I'll wait and see.
I've decided not to dig it out - too much risk of just spreading it and too much work !! I'm not keen on using chemicals, but in this case I think I'll try Round-Up or something similar in Spring as it starts growing and then just keep cutting it down, pulling it up until either one of us gives up.

Happy X-mas all

[William O]

Hi Reedos,

If you'r going to apply roundup I've read somewhere that the following is a good procedure for knotweed and invasive bamboo.
In spring, first cut it back and "wait" for the new growth. Then when the new growth is about 2 ft high apply roundup. Repeat the procedure as long as it takes.