Himalayan Balsam

As you say - its an annual, with very shallow roots and easy to pull up. Just pull it up or cut it down before it seeds. Not a big problem like Japanese Knotweed - now that is a real horror :eek:

 

Yes - there was some of that growing up from under concrete, pushing up through a brick wall, at a path up to a supermarket from the main shopping street in Hemel some years ago - and it took over the path!! The council didn't have any option but to deal with it - but whatever they did, it was effective, so they must have had someone who knew their stuff in charge of that one!