I spent a long time researching this on the net and in practice, trying to
remove a patch of about 80 sq metres of it from a garden.
I found there are three parts of this plant to deal with: the stalks, the
surface roots¹ and the deep underground rhizomes (the real problem). Each
part needs different treatment.
I found that repeated scything worked very well for the stalks, once they
have grown more than a foot or two, you just keep doing it, several times a
season. You lay them out to dry, preferably in the sun, and then either
compost them when they are totally dried out or burn them. Scything is
good in that you get a clean cut, without spreading living small fragments
around the place too much. It is also very satisfying and you can get
through a large patch quite quickly.
Then you are faced with the clumps in the ground. The scythed-off stalk
stumps eventually dry out and die. Pulling these out gives you the illusion
you are pulling the roots up. You can get a clump of root¹ stuff out with
each stalk, but of course this grows from a rhizome much deeper underground
some authorities say these rhizomes can grow down several metres, so it is
impractical to dig them out.
When you get these surface roots¹ out, you need to burn them. If you dry
them, they do not die and can regenerate. Do not compost these parts. Some
people worry about bonfires, as they are contributing to pollution, but if
you do burn these root clumps, the ash is good for fertiliser.
The only way you can attack the deep rhizomes is by total surface attack
remove all photosynthesising parts for a very long time (years?), or if you
are in a hurry you have to use chemicals which go all the way down, which I
confess I resorted to in the end, with great reluctance. However, this
did start to work at the edges of the patch, where I guess the rhizome
structure was weaker or younger I saw considerably less regrowth and new
shoots appearing. Some authorities say there is a danger that if you
apply too much of the weedkiller it can leach or leak out of the rhizomes
into neighbouring plants, so this might be a risk if you have valuable trees
nearby. However, I was using glyphosate (Roundup) which claims to be
inactive in the soil, so I don¹t know how it would carry across from the
rhizomes to the roots of another plant....maybe this would happen if the
rootlets were actually touching.
I had immense satisfaction in starting to deal with this problem: commercial
companies I approached quoted thousands of pounds to do the job and gave no
guarantees it would work without excavating the whole site to a depth of
five metres! I think I will have eradicated it by myself and with very
simple methods within 3 years, and using only a minimum of chemical.
By the way, the shoots taste horrible. I¹d rather have aspargus any day. Or
> -early shoots can be eaten like asparagus
> -goats & pigs love it but needs to be rationed because they will eat
> it until it makes them sick
> -we make panpipes & flutes from the dried stalks
> -& the famous Chinese tonic for long life Shou Wei is made from it
> & of course don't ever plant it where you're not gonna want it in 20
> On Feb 14, 2007, at 8:53 AM, Dee Harris wrote:
>> > I haven't had a chance to get to the original post about Japanese
>> > Knotweed so can someone fill me in? Is Japanese Knotweed only good
>> > for breaking down compost or is it good for other uses?
>> > Wolf
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