Description of several herbicides are listed for weed control prior to weed emergence, postemergence, and for postemergence directed applications. Tables are included showing the susceptibility of annual and perennial grass and broadleaf weed to herbicides labeled in shelterbelt and tree plantings. A detailed section has been developed listing herbicides that are labeled on many tree species grown in the Northern Great Plains. Common milkweed appears tolerant to most all labeled herbicides currently registered. Preventing common milkweed patches from spreading and establishment of new patches requires continuous scouting and persistent control efforts .
Seeds readily germinate and new plants readily become established from seed in fields.
New shoot developing from established roots begin emerging in late April and grow more rapidly than spring seeded crops. Increased control results from fall application of systemic herbicides due to greater movement to large buds that are closest to plant stems as they begin to develop. Ammonium sulfate stimulates root bud growth. Most herbicides did not reduce milkweed plant mass, height, or stand. Apply when milkweed is in the late-bud to flowering stage and actively growing.