0 = None
1 = Some (I am generally aware of knotweed, but do not know specific techniques for control)
2 = Moderate (I can usually identify knotweed, and know some techniques for knotweed control)
3 = More (I can identify knotweed, and know control techniques)
4 = Expert (I can identify knotweed, differentiating it from plants that look similar, and I provide advice to others on controlling knotweed)