In article , Pam Moore
writes
Many of the more stubborn weeds inc. Japanese Knotweed are considered to
be more likely to be affected by poison if sprayed as they are winding
down for the year as they take the stuff into the roots.

But in September, not now. Now is surely too late.

Pam in Bristol

I've got weeds that are only just dying down Pam!

--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk