If not completely controlling crown vetch, mowing offers a method of stopping its spread. Mowing around the periphery of a natural area threatened by crown vetch may keep the vetch from spreading into the natural area vegetatively but will not control the spread of seeds. Herbicides, at the present time, appear to be the most effective means of control. Another herbicide that shows some promise, but has not been tested sufficiently yet is Clopyralid 2,4-D amine is sold under a number of trade names. The amine, low volatility formation should probably be used over the high volatility ester formulation.
Drift can become a problem with the ester formulation.
2,4-D amine applied during the growing season will kill back the above ground portions, although there has been some survival of crown vetch in treated areas. This ineffectiveness of the herbicide could be the result of incomplete treatment, or re-establishment through seeds. There are some formulations of 2,4-D amine made just for controlling legumes. These formulations have not been tried, but may do a better job of controlling crown vetch. 2,4-D amine has the advantage of being dicot specific, so grasses will not be harmed.