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Japanese Knotweed (Fallopia japonica)


I have just been looking at the May edition of the RHS journal, ‘The Garden’ and it contains an article on Japanese Knotweed that both surprises and concernes me. The key points, for me, are the statements that:
1) It is illegal to plant or encourage growth in the wild. This I knew.
2) It is not illegal to grow the plant in gardens. This I also knew.
3) It is not a notifiable weed that needs to be reported to DEFRA or SERAD.
4) It is not illegal to sell it!!!! This is what surprises and concernes me but I see that there are several listings for cultivars in the Plant Finder.
5) It is illegal to dispose of Japanese knotweed in the houshold waste or by dumping in the countryside. It should be burned on site or taken to a licensed controlled waste disposal centre.
The article goes on to say how difficult it is to kill the knotweed and it may take several years of treatment with a glyphospate weedkiller to eradicate it.
I can not find the article on-line to give a link.

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Wow! Japanese knotweed is a problem over here too in some disturbs me that there seems no organic way to control the thing! I hate putting chemicals on good soil!

Fortunately, so far I have spotted none of this dread plant on our lil acre!
Thanks for the info...

22 Apr, 2010


thats could be quite a worry I believe that there are only 5 notifyable weeds, one -i think- is creeping thistle and another is ragwort which is really nasty and slowly kill any animal that eats it-- losing its bitterness when dry in hay! and as a human we should always use gloves to pull it up as it can go through the skin and cause liver damage. around here its the council themselves whohave the most on roadside verges etc.-- sorry for the rant but its nasty stuff

22 Apr, 2010


For the last ten years the British 'experts' have been trialing the use of a Japanese bug that lives on the sap of the knotweed - and nothing else, or so they say. Personally, I am wary of the introduction of a species to control another because I don't think anyone can be certain that it won't fancy something else! However, Healerwitch, it has been licensed but I have not yet heard of it being used.

22 Apr, 2010


I had it in some topsoil I bought. There were several bits and I dug them out. That was 2 yrs ago and I haven't seen it since. I complained to the seller and he said there should be no weeds at all in the soil but it was absolutely full of all sorts. I think they must have been in the manure that was mixed with it.

22 Apr, 2010


If you want to complain about the treatment in law there is a non-native species secretariat

22 Apr, 2010


interseting BH had some when i moved in and cleared all i could and pull it out as soon as i see it so it never really gets a hold again i leave it to dry out before disposing of it .. can`t regenerate from drying out can it ?

22 Apr, 2010


I saw a programme on TV ages ago about a woman who bought a site, in Kent I think, on which to build a house. It cost her about £2000 to have the site cleared and guaranteed free of the Japanese Knotweed before she was allowed to build. It seems mad to have regulations which are so un connected (disconnected). gives the information you are looking for BB Hywel if you put Japanese Knotweed Wales in your google box it will come up with interesting facts including mentioning those bugs to get rid of this noxious weed.

23 Apr, 2010


Thank you

23 Apr, 2010


lets just be greatful they only intrduced the female plant and not the male too. Or they would be seeding everywhere too.
there was an article on the news recently that they wre rleasing the predator 'bug' soon. lets hope it isnt a mistake like the kane toads [america I think] and rabbits 'down under'.

25 Apr, 2010


Interesting blog, Bulbaholic - I hadn't heard about the beetle, and am slightly concerned myself - whenever they try to put things right, there's always a usually unforeseen price. I was quite shocked by what I read on the Environment Agency's site about knotweed too, where it said it was classed as, can't remember exactly, think it was an eco hazard. Only found out because some poor soul had been given an allotment last year only to find the whole thing growing knotweed when he returned to cultivate in March and asked a question about it. Turns out its the Council's responsibility to deal with it, as they own the land.

11 May, 2010


Established knotweed has roots that go to a depth of 2 metres!
A pal of mine is a tree officer for a county council. During his research he found out that it cost about £10,000 to clear an area 50' x 10' !!!!!!!!!

With regards to the beetle, research has just about finished and they are about to be released under controlled conditions. The beetle only eats Japanese Knotweed leaves. Whilst this does not kill the plant, the second flush of leaves are stunted therefore weakening the vitality of the plant.

The cane toad problem in Australia came about through lack of research before release. They were brought in to combat insects/beetles damaging the sugar cane crops. The problem was the insects/beetles attacked the canes near the top of the canes and the toads feed on the ground eating every living thing that they could fit into their mouths. That and the fact that ANYTHING taking a bite of one would suffer a terrible death from poison secreted from glands (warts) on the toads back. Australia has no natural predators for the cane toad.
Some people in Oz let their children keep these toads as pets.
ps. nice blog.

29 Aug, 2010

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