Control of Johnson grass patches in cultivation using glyphosate

Abstract

Complete control was achieved with 0.09 percent glyphosate applied in November and again in February and April. Applications in November repeated in February (at concentrations up to 0.24 percent) or single applications in November or April (at concentrations up to 0.36 percent) failed to control the weed completely. At concentrations of 0.24 and 0.18 percent, there were no significant differences in initial control achieved irrespective of timing or number of applications. However, at 0.09 and 0.045 percent there were indications of greater activity of glyphosate when applied in autumn rather than in early or late summer.