Consider herbicide carryover if making use of cover crops

submitted by Sara Berges, Allamakee SWCD

If you are considering planting cover crops this fall, now is the time to be thinking about how your herbicide program could impact the establishment and success of your cover crop. If you are considering grazing your cover crop, you also may be concerned about herbicide residue accumulation in forage rather than just carryover injury. The best advice is to follow the label restrictions for rotation intervals.
Application rate can impact the effects of herbicides on cover crops. Higher application rates of more persistent herbicides can have more of an effect later in the season than a lower rate of the same herbicide. Producers that want to use herbicides with residual control need to read and follow the label to ensure they will not impact their intended cover crop.
Research by Practical Farmers of Iowa has shown that using Balance Flexx, Corvus and Hornet herbicides can have a negative effect on hairy vetch, lentil and radishes, while Dual II Magnum can cause carryover injury to cereal rye. Information from Penn State University can be found online that details the potential for specific herbicides to injure fall cover crops in a document called “Herbicide Persistence and Rotation to Cover Crops.”
Glyphosate should not harm cover crops at normal use rates. Liberty, Harness and Outlook may have residue concerns for feed. The important thing is to be aware of any potential herbicide carryover so that the cover crop has the greatest chance for successfully being established.