"Stuart Noble" wrote in message
m...
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

As it can push its way up through tarmac, I can't see plastic sheeting being
an effective barrier. And thick concrete won't be a barrier unless it goes
down several metres.

You can try repeated applications of glyphosate, especially as you say it
won't have anything done to it for a year. Other possibilities include the
path weed suppressants (most of which have been removed from the market),
but in my experience they weren't as effective as glyphosate. There are
some products around such as Weedol Rootkill Plus or Bayer Path Weedkiller
which might be more effective. Or you could try Sodium Chlorate.

Good luck!

--

Jeff