Efficacy and Rotational Crop Response to Levels and Dates of Dinitroaniline Herbicide Applications

Trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), dinitramine (N 4,N 4-diethyl-α,α,α-rifluoro-3,5-dinitrotoluene-2,4-diamine), profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro 2,6-dinitro-N-propyl-p-toluidine], fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine], butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine], and USB 3153 (N 3,N 3-di-N-propyl-2,4-dinitro-6-trifluoromethyl-m-phenylenediamine) were applied to evaluate weed control, cotton (Gossypium hirsutum L. ‘Dunn 119′) tolerance, and effect on rotational crops. Each herbicide was applied at 1-month intervals for 6 months prior to planting at 1, 1.25, 1.5, and 2X the recommended rates. Pigweed (Amaranthus hybridus L. and A. retroflexus L.) population counts and visual control ratings showed that weed control improved when treatments were applied closer to planting. Applications in November and December at 1.25X profluralin, 1.5X trifluralin, fluchloralin, and pendimethalin, 1X USB 3153, and 2X butralin were required to give effective weed control. Spring applications of 1X rates of profluralin, trifluralin, fluchloralin, and USB 3153, 1.25X rates of pendimethalin and dinitramine and 1.5X rate of butralin were required for adequate weed control. USB 3153 at all rates and dates of application severely limited growth and yields of wheat (Triticum aestivum L. ‘Funk 332′) planted after harvest and also the following May. Spring applications of profluralin at 1.5 and 2X rates and trifluralin at the 2X rate resulted in significant injury of rotational sorghum [Sorghum bicolor (L.) Moench ‘Dekalb E-59+’].