Johnsongrass Control in Conventionally Tilled and No‐Tilled Soybean with Foliar‐Applied Herbicides

Abstract

AbstractPerennial johnsongrass [Sorghum halepense (L.) Pers.] is costly and difficult to control in soybean [Glycine max (L.) Merr.]. Selective and nonselective foliar‐active herbicides were evaluated for activity and residual control of rhizome johnsongrass in conventional‐ and no‐till soybean culture. Broadcast foliar applications of selective graminacides and rope‐wick applications of nonselective foliar‐active herbicides were applied to rhizome johnsongrass growing in conventional‐till and no‐till soybean in 1984 and 1985. Selective graminacides generally provided excellent johnsongrass control (90 to 100%) that resulted in higher soybean yields than plots treated with rope‐wick applied herbicides. Selective graminacides also provided greater suppression of johnsongrass regrowth in the year following treatment compared with the nonselective herbicides. Two applications of selective graminacides did not improve johnsongrass control as compared with one application. Two rope‐wick applications of glyphosate [N‐(phosphonomethyl)glycine] or sulfosate (trimethylsulfoniumcarboxy methylaminomethylphosphonate) improved johnsongrass control, as compared with one application, in one of two years, but soybean yields did not always equal that applied with selective graminacides. Tillage did not significantly affect johnsongrass control with any of the treatments.