Crown vetch is part of the pea family of plants and is an invasive species in much of the United States. It is a perennial of European origin and although it provides control of erosion, it grows and expands, taking over an area and shading out other plants. The Missouri Department of Conservation's website reports that one plant can cover as much as 100 square feet in just four years. There are ways to get rid of crown vetch.

Identify Crown Vetch

Recognize crown vetch when it is on your property. The plant has creeping stems as long as 10 feet, dark greenish leaves and flowers that develop into narrow seed pods as long as 3 inches. It can be as tall as 6 feet. It spreads rapidly through rhizomes, a system of underground stems that make it difficult to eradicate. The leaves are compound, with 15 to 25 separate leaflets comprising a single leaf. Identify crown vetch most easily by its flowers when it blooms, typically between late spring and into summer. They grow in clusters known as umbels on the very ends of long stalks; they range from white to a dark pink and resemble flowers such as the sweet pea.

Mow Crown Vetch

Mow crown vetch repeatedly to control its spread. Mowing the plant down will give you an opportunity to then attack it in other ways. The underground rhizomes make it possible for the species to come back rapidly even after you mow it to the ground. Mow crown vetch in the late spring and several times before the summer starts to prevent it from thriving. Mow the borders of an area of crown vetch where seedlings might be growing. Realize, though, that you will have to mow a patch of established crown vetch over a period of years to eradicate it in this way.

Spray Crown Vetch

Use a trio of herbicides to get rid of crown vetch via spraying. While mowing can slow down crown vetch, a herbicide treatment after you mow can take a much heavier toll on the invasive plant. The Invasive Plant Species Assessment Working Group website says the herbicides known as 2, 4-D amine, Glyphosate and Triclopyr are effective agents for this purpose. Apply 2, 4-D amine to the leaves of crown vetch in the early spring; this herbicide does not kill the surrounding grass if there is any. Glyphostae is a choice if your infestation of crown vetch is small, but remember that this solution kills all the plants that you spray, not just the undesirable one. Triclopyr works the best of these three, especially on a large area taken over by this species. Use a backpack sprayer or a pump sprayer and saturate the crown vetch thoroughly. Repeat the sprayings until you finally have killed off the plants, which may take several growing seasons to accomplish.

Source:

Invasive Plant Species Assessment Working Group:Crown Vetch

Missouri Dept of Conservation:Crown Vetch