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. The following treatments may cause significant crop injury and death if applied on cropland. Growers must determine the benefit from control against crop loss from excessive herbicide rates applied. In addition, Tordon will leave a residue for several years and may injure crops grown in successive years.