Johnsongrass Control in Soybeans by Trifluralin and Nitralin

Abstract

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.