The impending release of cotton cultivars with resistance to auxin herbicides, either 2,4-D or dicamba, will likely greatly increase the usage and thereby the potential for off-target movement of herbicides onto non-tolerant cotton. Determining the response of cotton without tolerance to these herbicides will be critical moving forward as we deal with an increasing number of drift and other misapplication incidents. This presentation is aimed at providing growers, county agents, and consultants information on cotton response to sub-lethal rates of 2,4-D from locations across the Cotton Belt. Specifically, this presentation will contain the results of a study performed at 7 different locations across 6 states on the effect of simulated 2,4- D drift and 2,4-D tank contamination scenarios on cotton. These simulated drift and tank contamination rates were applied at 6 different timings during the growing season to determine the sensitivity of cotton to 2,4-D across a wide range of growth stages. These results illustrate the differing response of cotton development, yield, and injury symptoms to 2,4-D at these various growth stages.
