1. Urban garden in Massachusetts.2. Rural lot in New Hampshire.
If you are in England or Wales get a solicitor to serve an order to Network rail under the Pernicious weeds Act. This will force them to treat the knotweed. (there may be a similar bit of law in Scotland but I do not know what it is). It is illegal to allow knotweed to grow where it could cause problems.
I assume you mean Polygonum cuspidatum.This is a really obnoxious weed. I don't know other than to keep at it..destroying every piece of it constantly. Maybe chemicals may be the only way to get it under control..you might get some leads at this site www.invasivespeciesinfo /plant...
