Control of Quackgrass With Glyphosate and Additives

Addition of nonionic surfactants nonylphenoxyl polyethoxy ethanol at 0.1% of total spray volume (vol/vol), tallow amine ethoxylate at 0.5% (vol/vol), or oil concentrate at 1% (vol/vol) to commercially formulated glyphosate applied at 0.25 and 0.5 kg a.i. ha−1 improved control of quackgrass [(Agropyron repens (L.) Beauv.)]. However, the improvement was not sufficient to provide an acceptable level of control of quackgrass. Addition of ammonium sulphate to glyphosate gave significantly greater control of quackgrass at all three rates of glyphosate. In one of the two experiments, control with 0.5 kg a.i. ha−1 of glyphosate was comparable to that of 1.0 kg a.i. ha−1. Addition of either of the three surfactants to the ammonium sulphate and glyphosate combinations did not further enhance control.Key words: Ammonium sulphate, nonylphenoxy polyethoxy ethanol, tallow amine ethoxylate, oil concentrate, Agropyron repens (L.) Beauv.