Knotweed spreads by fragments of root and stem, and moving water carries those fragments a long way. Banks along the Irwell, the Manchester Ship Canal and the Bridgewater Canal are therefore some of the most likely places to find it in Salford.
What it means for your plot
If your garden or yard backs onto a river, canal or brook, check the rear boundary each spring for red-purple shoots and again in summer for tall hollow canes.
Whose job is it
The owner of the land where it grows. A survey of your own side records whether it has crossed the line, which is the evidence you need to raise it.