Loss of a Riverbank: Knotweed and other invasives
Knotweed is very difficult to eradicate, but it can be controlled by various methods including a late spring frost; cutting and disposing so cuttings can’t sprout; creating a greenhouse effect with plastic; and chemical control. A new method of chemical control is a system that injects concentrated herbicide directly into stems. This is initially labor intensive, but is proving to be effective in eliminating a patch of knotweed. This has the added advantage of not harming other plants in the area.
The bottom line is that you must be persistent and will probably need to employ several different types of control over a few seasons to completely eliminate this invasive pest.