Here in Birmingham,it's a 'notifiable' pest weed - we successfully stopped the council taking part of the area we walk dogs/pick blackberries etc.etc. when we notified of them of it for some, oh! 3 years or so? while they barricaded off the area & dealt with it. Even then, the area, which had been earmarked for building, was then changed to be a car park....
We're not allowed bonfires, but to dispose of bags of knotweed we are supposed to NOT put it in the garden refuse sacks or black bags for landfill, but to telephone them to collect & dispose of separately...fine, if people know what it looks like....