Cotton Response to Pre-Emergent Herbicides in an Irrigated, Sandy Environment

With over 1 million acres of cotton in Georgia and over 30,000 acres in Thomas County, the use of pre-emergent herbicides is critical for cotton to obtain profit. In Georgia, Palmer amaranth has cost cotton growers over 1 billion dollars from 2004 to 2014 and continues to plague the industry. Multiple pre-emergent chemistries must be used to maintain pigweed control. However, these herbicides can cause crop injury.  Factors most often influencing injury consist of soil type, herbicide and rates applied, and irrigation scheduling or rainfall.  An experiment was conducted to determine cotton response when Reflex plus Warrant, Direx plus Warrant, Reflex, or Brake F2 were applied immediately after planting on a loamy sand soil.  The crop was irrigated at 2 days after plant and not again until after the crop had completely emerged. The greatest level of injury noted was 7% at 11 days after treatment.  The lack of injury is most likely a result of a well-timed irrigation program.