Italian ryegrass management in Oklahoma winter wheat

Abstract

Two field and greenhouse studies were conducted to evaluate Italian ryegrass management in Oklahoma winter wheat. Herbicide treatments included flufenacet + metribuzin, metribuzin, pinoxaden, and pyroxasulfone applied very early postemergence and/or mid-postemergence. For the field experiment during the 2016-17 season in Perkins, OK, Italian ryegrass was controlled 97% or greater for all treatments containing pyroxasulfone. Control levels with treatments containing pyroxasulfone in the 2017-18 season were among the top performing treatments; however, limited herbicide to soil contact due to high levels of straw residue at the time of application and the absence of a timely rain after application decreased the overall level of Italian ryegrass control with pyroxasulfone compared to the 2016-17 season. Suspected pinoxaden resistant Italian ryegrass biotypes from the 2016-17 season were screened for resistance in the spring of 2018. Results suggest that biotypes from the Perkins field population have an increased tolerance to pinoxaden, but do not fit the description to be classified as pinoxaden resistant.