Yellow nutsedge (Cyperus esculentus L.) control in corn with various rates of halosulfuron

Abstract

There are a limited number of herbicide options that provide commercially acceptable control of yellow nutsedge in corn. A study consisting of nine field experiments was conducted during 2013–2016 in growers’ fields in Ontario to evaluate the efficacy of glyphosate plus various rates of halosulfuron applied after emergence (post-emergence, POST) for the control of yellow nutsedge in glyphosate-resistant corn. Glyphosate (900 g a.e. ha−1) plus halosulfuron applied POST at the registered rate of 34–68 g a.i. ha−1 caused minimal injury in glyphosate-resistant corn. The predicted halosulfuron rates needed to control yellow nutsedge 50%, 80%, and 90% were 3, 24, and >140 g a.i. ha−1 at 4 weeks after herbicide application (WAA) and 2, 13, and 73 g a.i. ha−1 at 8 WAA, respectively. The predicted halosulfuron rates required to reduce yellow nutsedge density 50%, 80%, and 90% were 13, 42, and 109 g a.i. ha−1, respectively. In addition, the predicted halosulfuron rates required to reduce yellow nutsedge dry weight 50%, 80%, and 90% were 6, 23, and 54 g a.i. ha−1, respectively. Contrasts comparing halosulfuron (35 g a.i. ha−1) with other herbicides showed that glyphosate plus halosulfuron provided as much as 35% greater control of yellow nutsedge than glyphosate plus bentazon (1080 g a.i. ha−1) and as much as 22% greater control of yellow nutsedge than glyphosate plus tembotrione/thiencarbazone (45 g a.i. ha−1).