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Bob Hobden · 15-02-2010, 06:39 PM posted to uk.rec.gardening

"Charlie Pridham" wrote ...
says...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front garden in question won't have anything done to it for a year, so
it would be a convenient time to cover it and treat any shoots appearing
at the edges. There is thick concrete either side, so with luck it won't
find its way past that. However, I don't want to create a damp
hothouse environment that might make matters worse over the summer. Any
advice appreciated

Repeated applications of Glysophate are your best bet, the NT cut the
stems during its growing season and squirt glysophate down the hollow
stems, there are web sites where information and advice can be found but
I fortunately do not have this problem.
Plastic sheet would last less than a week and it would be through, I have
seen it come up in the middle of roads and through 3" of concrete.
I have seen some reports of mowing it twice a week weakening it but have
wondered what you do with the mowings as its an offence to dispose of any
part of the plant without a licence!

I've seen articles saying the young 8 inch shoots are edible and delicious,
like Rhubarb but better, and that if you keep cutting them off so the plant
cannot photosynthesise it eventually dies. How long that takes is anyone's
guess.
Personally I would use the Glyphosate down the cut stem method to kill those
deep roots and dry and burn the cut stems.

--
Regards
Bob Hobden
W.of London. UK