Johnsongrass Control in Soybeans with Soil-Incorporated Dinitroaniline Herbicides

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.

Johnsongrass Control in Soybeans by Trifluralin and Nitralin

Field experiments were conducted to study the feasibility of using trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline] for the selective control of johnsongrass [Sorghum halepense(L.) Pers.] from rhizomes and seed in soybeans[Glycine max(L.) Merr. ‘Lee’]. Both herbicides were incorporated into the soil at 0.56 to 3.36 kg/ha with two disk cultivations immediately after application. Most effective johnsongrass control on Dundee silty clay loam (sicl) followed treatments of nitralin or trifluralin at 1.68 to 3.36 kg/ha, but 2 years or more of continuous treatment were required for acceptable control. Trifluralin at 1.12 and 2.24 kg/ha on Sharkey clay and at 0.56 to 2.24 kg/ha on Bosket fine sandy loam (fsl) provided better average johnsongrass control over a 2-year period than nitralin at the same rates, but soybean yields after both herbicides at the same rates were equal. Immediate incorporation of trifluralin or nitralin in all three soils at 1.12 to 2.24 kg/ha for 2 successive years effectively controlled johnsongrass from rhizomes without soybean injury and with greatly increased soybean yields.