Cover crops can be grown for many purposes, including reducing soil and wind erosion, weed suppression, nitrogen benefits and soil health improvement. For some growers, cover crops may be grazed, bailed or harvested as silage. Others intending to grow a cash crop following cover crops grazing will need timely cover crops termination to prevent competition with the next cash crop. Termination choices may include selecting species that winter kill, chemical applications and/or tillage.

Cover crop species such as oats, sorghum-sudangrass, oilseed radishes, winter peas and turnips generally die naturally over the winter, with some exceptions. Many grass species like cereal ryegrass, winter barley, triticale and wheat can survive winter temperatures and provide soil protection and weed suppression into spring.

These species may require herbicides like glyphosate (Roundup®) combined with burndown 2,4-D, saflufenacil (Sharpen®) or dicamba herbicides to control winter annual weeds, clover and alfalfa. Chemicals like Surestart®, TripleFlex®, Hornet® or Stinger® are usually more effective on clover and alfalfa control. Burndown herbicides should not be spring-applied unless there are one to two days with temperatures over 50°F to assure good results.

Remember that there is a fine line regarding growing cover crops with late spring termination to attain higher biomass without reducing grain crop yields. Follow NRCS cover crop termination guidelines for non-irrigated fields. For central and western Nebraska crop insurance, cover crops must be terminated at least 15 days prior to planting. For eastern Nebraska, cover crops can be terminated at or before planting.

Non-selective Gramoxone (paraquat) and can be effective on controlling tall cereal rye but is not consistently effective killing winter wheat. Glufosinate (Liberty®, Rely® or Noventa®) may also be alternatives during cooler springs. The key to successful herbicide termination is complete plant spray coverage. Tillage may speed up residue breakdown but may also negate some of the cover crops benefits.


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