Hazards
Knotweed is not known to present any significant health hazards to humans.
First-Aid
Hand washing is recommended after handling knotweed.
Risk Management
Dense knotweed thickets can conceal hidden objects, so extreme care should be used during mowing operations to prevent equipment damage and injuries.
Control
Knotweed is a serious threat to biodiversity and quality wildlife habitat such as streamside areas and wetlands. Its aggressive growth can penetrate pavement, obstruct roadway sightlines, and will increasingly displace native vegetation.
Once established in an area, knotweed is very difficult to eradicate. Systemic herbicides such as glyphosate are usually ineffective unless applied intensively and repeatedly. Small patches can be mowed and then covered with heavy black plastic to shade out new sprouts.
Most seed produced by knotweed is sterile, so spreading occurs primarily through the movement of fill that is contaminated with root fragments. Consequently, extreme care should be used not to introduce potentially contaminated fill into areas that are still free of knotweed.
The best method of control is prevention of spreading knotweed to new areas! Excavation sites that receive potentially contaminated fill should be monitored for at least two years for knotweed. New outbreaks are easiest and most economical to control if caught in the early stages of establishment.
Single young plants can be hand-pulled.