Madam, - Paul Bennett (September 6th) says not even Roundup has been able to remove his extensive bed of Japanese knotweed. We were told our only hope was to spray our plants every autumn for five years, and that would do it. After only three years, the treatment worked - though we also covered the area, some time after spraying, with sheets of thick plastic. - Yours, etc,
HILARY WAKEMAN, Schull, Co Cork.