Effect of Carrier Volume on Grain Sorghum Response to Simulated Drift of Nicosulfuron

Abstract

Research was conducted in 2010 and 2012 to determine the effect of simulated drift of nicosulfuron on growth and yield of grain sorghum. Herbicide rates represented 25, 12.5, and 6.3% of the use rate of nicosulfuron at 52 g ai ha−1. Nicosulfuron was applied in a constant carrier volume of 224 L ha−1where herbicide concentration decreased with reduction in rate, and in carrier volumes of 56, 28, and 14 L ha−1proportional to the 25, 12.5, and 6.3% herbicide rates, respectively. In 2010, grain sorghum injury and yield were greater when nicosulfuron was applied in constant compared to proportional carrier volume. Grain sorghum injury and plant height reduction increased with increasing nicosulfuron rate when averaged across carrier volume both years. In 2012, there was a greater reduction in grain sorghum yield from nicosulfuron applied in proportional carrier volume. These data indicate that simulated drift of nicosulfuron onto conventional grain sorghum causes significant height and yield reduction even at the lowest herbicide rate tested, and the effect of carrier volume may be influenced by seasonal rainfall.