February’s Weed of the Month, narrowleaf bittercress (Cardamine impatiens) is a relative newcomer to Minnesota and has the potential to become highly invasive. Native to Eurasia, it was first reported in New England in the early 1900s. In 2009 multiple infestations were reported in several counties in Minnesota.
Narrowleaf bittercress is an herbaceous annual or biennial in the mustard family that grows over two feet tall. It starts its first season as a basal rosette and in its second season sends up a flowering stem. When the plant is in the rosette form, the leaflets are rounded; as a mature plant, the leaflets are sharply toothed. The plant blooms May through August, producing very small white flowers which form numerous slender seed pods.
Narrowleaf bittercress prefers forested floodplain habitat. It does well in partial sun and moist soils, and can form dense stands that outcompete native plants. Infestations of this plant result in decreased species diversity and habitat quality. Because of its prolific seed production, it can spread very quickly, and has been reported spreading along the St. Croix and Mississippi Rivers.
As a prohibited noxious weed on the control list, landowners must attempt to control the spreading of propagating parts of this plant by preventing the seed from maturing. To manage narrowleaf bittercress, infestations need to be monitored and treated until the seedbanks are depleted.
• Clean all boots, clothing, and equipment to avoid spreading the seed.
• Small infestations can be hand pulled. The goal of removal is to prevent seed production. Minnesota Department of Agriculture (MDA)/Minnesota Department of Health removal recommendations should be followed: http://www.mda.state.mn.us/plants/pestmanagement/weedcontrol/disposalnoxweed.aspx
• Herbicide may be an option. For specific herbicide recommendations, contact the University of Minnesota Extension.
• Improving vegetation quality may help native plants outcompete narrowleaf bittercress and help reduce infestations.
To report infestations of narrowleaf bittercress or any other prohibited noxious weeds, please notify MDA by email at firstname.lastname@example.org, or phone 1-888-545-6684 (toll-free).