Once a cover crop is established, farmers need to prepare to manage it for the following crop. Cover crops can act as weeds if not controlled. Controlling cover crops in no-till systems is more difficult and less predictable and chemical control may be warranted. Legumes may be killed at flowering by flailing or mowing. It is critical that cover crops be controlled in spring to prevent them from interfering with the row crop. Control is especially important during a dry spring.
Cultural: Several cover crop species cannot survive Michigan winters. These cover crops will die over the winter (winter kill) without the need for mechanical or chemical control. Examples: Oats, Berseem clover, oilseed radish and annual medics.
Mechanical: Traditionally, farmers moldboard plowed to control cover crops. This is a very effective means of control, although some grass species (annual ryegrass, cereal rye) can cause rapid soil drying and plowing becomes very difficult if it is not done early. Unfortunately, reduced tillage systems often will not provide complete cover crop control.
Chemical: The two herbicides that seem to fit best for control of cover crops are 2, 4-D ester and glyphosate. To maximize chemical control, it is extremely important to time the herbicide application to the correct growth stage of the cover crop. A table detailing the effectiveness of herbicides for terminating cover crops is listed in the bulletin below.
Cover Crop Termination bulletin from MSUE (March 2020)
Cover Crop Termination Strategies webinar from MSUE (March 2016) featuring Mike Plummer.