Johnsongrass Control in Soybeans with Soil-Incorporated Dinitroaniline Herbicides

Abstract

Field experiments were conducted to study the feasibility of using several dinitroaniline herbicides for the selective control of johnsongrass [Sorghum halepense(L.) Pers.] from seed and rhizomes in soybeans [Glycine max(L.) Merr. ‘Bragg’]. The herbicides were incorporated into the soil with two disk cultivations immediately after application. These were trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 0.6 to 2.2 kg/ha, nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline] at 0.6 to 2.2 kg/ha, dinitramine (N4,N4-diethyl-α,α,α,-trifluoro-3,5-dinitrotoluene-2,4-diamine) at 0.4 to 1.5 kg/ha, fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline] at 0.6 to 2.2 kg/ha, profluralin [N-(cyclopropyl-methyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine] at 0.8 to 3.4 kg/ha, butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine] at 1.7 to 6.7 kg/ha, AC-92390 (N-sec-butyl-2,6-dinitro-3,4-xylidine) at 0.8 to 3.4 kg/ha, and AN-56477 [N,N-di(2-chloroethyl)-4-methyl-2,6-dinitroaniline] at 2.2 to 4.5 kg/ha. On Bosket sandy loam soil, the best average johnsongrass control over a 2-yr period was obtained following profluralin at 1.7 kg/ha and butralin at 3.4 kg/ha. These treatments also resulted in highest average soybean yields. On Sharkey clay soil, profluralin at 3.4 kg/ha and butralin at 6.7 kg/ha resulted in maximum johnsongrass control and soybean yields. Immediate incorporation of profluralin and butralin into both soils for 2 successive years effectively controlled johnsongrass from rhizomes without soybean injury and with greatly increased soybean yields. Trifluralin, nitralin, and fluchloralin also provided acceptable johnsongrass control within individual experiments, and greatly increased soybean yields.