While the cover crop is growing, it will suppress the germination and growth of fall and early spring weeds through competition and shading. When killed and left on the surface as a mulch, cover crops continue to suppress weeds, primarily by blocking out light.
Cover crops can also suppress weeds chemically .
Researchers have effectively used cover crops of wheat , barley , oats , rye , sorghum, and sudangrass to suppress weeds. Weed suppression has also been reported from residues and leachates of crimson clover , h airy vetch , and other legumes. For more information, see the Contribution of Cover Crop Mulches to Weed Management . This site is owned by WSU .