A number of questions have come in over the past several days on how best to destroy a partial stand of corn and replant back to corn. Apparently there will be several corn fields that will have to be replanted.
There are several options to control a thin corn stand and replant back to corn. Some of these options, like Select Max, need a waiting period before it can be planted back to corn. Others, like tankmixes of paraquat plus atrazine, allow corn to be replanted right away. Please find attached the results of a study Angela McClure and I conducted ten years ago on destroying freeze damaged corn and replanting back to corn. We repeated the study the next year (2008) on a good stand of corn and got the same results. In this publication (Replanting corn in a failed corn stand) you will find a number of different herbicide options that did a good job controlling an unwanted stand of corn.
Many over the past decade have used the recommendations to satisfactory results. The most consistent time to control an old corn stand is around the V2 corn stage, which was the timing the research was conducted. Our experience has been over the years that once the old corn stand matures past V2 results from the herbicides in the publication will likely be more sketchy. In those cases, consider using higher rates of the herbicides in the publication to improve the chance for good control.