Pioneer Crop Insights

Pioneer Crop Insights

Successful weed resistance management requires a corn producer to thoughtfully choose the proper tools for weed management consistent with his farm operation.

Uncontrolled grass weeds such as the foxtails, different species of Panicum, and various species of crabgrass are particularly powerful in preventing corn from attaining its maximum yield.

Primary Herbicides Families for Grass Control in Corn

  • Chloroacetamides (acetochlor, s-metolachlor, dimethenamid, flufenacet, and related a.i.’s)
  • Sulfonylureas (nicosulfuron, rimsulfuron)
  • Glyphosate

Growers rely primarily on 3 herbicidal modes of action for grass weed control in corn. The first mode of action inhibits very long chain fatty acid synthesis. This mode of action includes the chloroacetamide herbicides (products containing acetochlor, dimethenamid, flufenacet, s-metolachlor, and chemically related active ingredients and is effective for preemergence grass control.

The second mode of action inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSP), which eventually leads to the depletion of the essential aromatic amino acids, tryptophan, tyrosine and phenylalanine. Glyphosate is the only active ingredient with this mode of action and is very effective for postemergence grass weed control in glyphosate-tolerant corn.

The third mode of action inhibits acetolactate synthase, a key enzyme in the production of the essential amino acids isoleucine, leucine and valine. This mode of action contains the sulfonylurea herbicides (products containing nicosulfuron, rimsulfuron, and chemically related active ingredients). Nicosulfuron is effective for postemergence grass control in corn. In addition to its postemergence grass weed activity, rimsulfuron is also effective for preemergence grass weed control in lower organic matter soils.

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