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April Weed of the Month: Crown Vetch

Recently added to Minnesota's Restricted Noxious Weed List, crown vetch (Securigera varia) is difficult to control once it is established. It is native to central and Eastern Europe and the Caucus region of Asia. Crown vetch was widely planted as a groundcover, cover crop, and slope stabilizer, but these uses declined due to the invasive nature of the plant.

Crown vetch is an herbaceous perennial in the legume family. It has a low, groundcover growth habit. The leaves are dark green and pinnately compound with 15-25 pairs of oval-shaped leaflets. The flowers are pink to white and occur in clusters at the leaf axils. The plants bloom from May through August.

Crown vetch spreads by seeds and aggressive rhizomes. The rhizomes grow horizontally up to 10 feet and produce new plants vegetatively. Crown vetch can be introduced to new areas by soil contaminated with root fragments.

Crown vetch invades prairies, woodland edges, streambanks, pastures, rights-of-way, and roadsides. It prefers open and sunny habitats, is tolerant of all different soil types, and is drought tolerant. Crown vetch overtakes and suppresses other vegetation, reducing species diversity and wildlife habitat. Because of its low, creeping growth habit, it can cover and shade out other plants, eventually forming dense monocultures.

Several management strategies may be necessary to keep crown vetch from spreading:

• Infestation sites will need to be monitored for several years and treated repeatedly until the seedbanks are depleted.

• Do not plant crown vetch and use alternative cover crops or native plants that can be used for soil stabilization.

• Mowing can be effective to slow the spread. Timing is crucial when mowing, with the goal of preventing seed formation. Mowing will have to be done for many successive years and may have to be followed up with herbicide treatments.

• Prescribed burning in late spring for several successive years can be an effective control method. Contact the Minnesota Department of Natural Resources to learn more about burning practices and regulations.

• Large infestations may be treated with herbicide. Contact your local University of Minnesota Extension agent, co-op, or certified landscape care expert for assistance and recommendations.


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