Field experiments showed that quackgrass could be controlled by glyphosate applied preharvest to barley. In separate experiments, field mint was controlled by glyphosate applied pre- and postharvest to barley and wheat. Suppression of quackgrass regrowth one year following treatment was 90% or greater when glyphosate was applied at 0.9 kg ai/ha alone or at 0.45 kg ai/ha in combination with both tallow amine ethoxylate at 0.5% of total spray volume and ammonium sulfate at 3 kg/ha. Field mint shoot counts were reduced 84% the year following treatment when glyphosate was applied at 0.25 kg ai/ha and 95% when applied at 1.0 kg ai/ha. Suppression of field mint shoot regrowth the following year was 84% when glyphosate was applied postharvest and 93% when applied preharvest. Addition of tallow amine ethoxylate did not improve field mint control. Glyphosate applied preharvest to barley and wheat at less than 30% grain moisture content had no effect on grain yield.
