The Effect of 2,4-D Drift Rates on Cotton (Gossypium hirsutum L.) Growth and Yield

Abstract

Research comparing the effects of five reduced 2,4-D rates on cotton growth, node development, and yield after herbicide exposure at the 4- to 6-leaf stage was conducted at the Texas A&M Field Laboratory near College Station, Texas in 2001, 2002, and 2003. These data were used with those from previous research quantifying 2,4-D injury to correlate yield loss. Yearly environmental conditions during the three-year study had significant effects on much of the data. Plants exposed to 2,4-D rates as high as 5.3×10-4 kg a.i./ha showed no reduction in height during 2001 or 2002, but stunting was observed in 2003. The highest 2,4-D rates, 5.3×10-2 and 2.7×10-1 kg a.i./ha, had no effect on the number of plant nodes but decreased bolls on reproductive growth and increased bolls on vegetative growth during 2001 and 2003. Vegetative boll production was unaffected in 2002. Plots exposed to 2,4-D rates as high as 5.3×10-3 kg a.i./ha experienced no yield reduction. The ability to predict yield loss after early-season 2,4-D injury seems possible, with high correlations between total plant injury and yield during 2002 and 2003 (R2 = 0.82 and 0.80, respectively). The correlation between injury and yield was lower in 2001 (R2 = 0.50). Accepted for publication 16 February 2014. Published 2 June 2014.