Response of Stoneville Cotton to Low Rates of Dicamba and 2-4-D

Weed control by use of herbicides is an important tactic in successful crop production. Two new technologies have recently entered the market that will allow producers to spray dicamba or 2,4-D over-the-top of cotton and soybean. Dicamba-tolerant soybean and cotton are commercially available and marketed as “Xtend” and 2,4-D tolerant crops will be called “Enlist”.  Although new technologies are beneficial for the control of herbicide-resistant weeds, there are concerns with the application of these herbicides with off-target movement, or drift. Field study was conducted in 2019 at the Delta Research and Extension Center, in Stoneville, Mississippi, to evaluate Stoneville cotton (ST 4949) injury at various low rates of 2,4-D and dicamba (1/16 X, 1/32X, and 1/64X) and to assess which crop growth stage is more sensitive than the others. All applications were made at three cotton growth stage: 3- to 4-leaf, square, and at flowering. Dicamba (1X) and 2,4-D (1X) rates are 16 and 32 fl oz/A, respectively.