The weed control in cotton has gotten off to a rough start in a number of fields.  In some fields the flowering Palmer amaranth has grown back from the paraquat burndown near planting.  These fields now have re-growing Palmer amaranth in the newly emerged cotton (picture left).

Many of these fields that were in Liberty-tolerant cotton were sprayed last week with Liberty to try to take out this regrowth. In most cases these follow up Liberty applications look to be successful.  However, please keep an eye on fields where the Liberty was applied more than 10 days after the Gramoxone as the Palmer may grow back and will need to be re-sprayed.  I would expect a sequential application of Liberty applied about 7 days apart should take out this regrowth.  In Roundup Ready cotton some have tried to overspray with Cotoran + MSMA with poor results.  Depending upon the Palmer density, a chopping crew or replant may be the best options for these fields. 

There has been a wide set of results to the pre plant and pre emergence applied herbicides in cotton.  This is mostly dictated by whether there was rainfall and the timing of this rainfall around the establishing cotton stand.  We still have significant cotton acres that have gotten very little rainfall.  The pre applied herbicides in these cases were not activated and post applications of Liberty are needed fast in fields of Liberty-tolerant cotton. In a few other areas, heavy rainfall fell and activated the herbicide as the cotton was emerging causing loss of cotton stand.

I have gotten calls about either the pre plant or pre applied herbicide as a major cause for poor cotton stands.  Notably different from last spring, no one herbicide seems to be the problem.  I have gotten calls about both Caparol and Cotoran in various fields causing some injury to cotton stands.  In other cases Reflex applied 21 to 14 days pre plant seemed to be involved in some cotton injury and in at least one case Valor applied 32 days before planting on dry soil was apparently activated with rain shortly after cotton planting and caused some damping off.   

In a few of cases, what was first thought to be damping off primarily due to the herbicide upon further inspection was found to be due to false chinch bug. Regardless the reason for the poor cotton stands, they now have to be assessed for their viability. Chris posted a good blog on May 12 about assessing poor cotton stand establishment and tips on replanting.