Prevention: Once established, swallow-wort is difficult to control. Monitor for populations in late summer, when the plants turn golden yellow and pods are present. Initial control efforts should concentrate on plants in sunny areas since they will produce the most seeds. Stay out of infested areas during seed dispersal to prevent seed dissemination to unaffected areas. Likewise, clean boots, ATVs, and other equipment when coming out of infested areas.
Physical/Mechanical Control: Small patches can be dug out by hand. The entire plant must be removed and destroyed. To prevent seed dispersal, pods should be removed before they open, and then burned.
Large stands can be managed by consistent mowing when pods are very small (May-July). Controlled burning is not effective and may improve site conditions for seedling establishment.
Chemical Control: Triclopyr or glyphosate can be applied to foliage around mid-September. Use of a surfactant helps herbicides penetrate the waxy leaf coating. Cut-stem treatment with glyphosate is effective but labor intensive. Use of systemic “Round Up” herbicide is also effective in removing swallow-wort.
For more information:
Center for Invasive Species and Ecosystem Health
Michigan Department of Natural Resources Michigan Natural Features Inventory https://mnfi.anr.msu.edu/invasive-species/Swallow-wortBCP.pdf