No. 9 Article 7/May 22, 2009

Some Additional Thoughts About Managing Weeds Before Planting

While many species of winter annual weeds are nearing completion of their life cycle, summer annual weed species appear to be thriving in fields where no weed management operation has occurred. Giant ragweed plants taller than 12 inches populate numerous fields, very dense populations of common lambsquarters are common, and waterhemp is enjoying the ample precipitation and soon-to-be-increasing air temperatures forecast for later this week.

In no-till situations, planting herbicide-resistant hybrids and varieties lets farmers plant first and spray weeds later (perhaps even as late as after crop emergence) with a nonselective herbicide such as glyphosate or glufosinate. Prior research has demonstrated that delayed burn-downs can sometimes provide satisfactory weed control, but this practice introduces significantly more risk for loss of crop yield potential than if weeds are adequately controlled prior to planting. Following are a few additional thoughts about managing weeds before planting.

--Aaron Hager

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