Control of Downy Brome (Bromus tectorum) in Winter Wheat (Triticum aestivum) with MON 37500

Abstract

Field experiments were conducted to determine suitable application timings and rates of MON 37500 for downy brome control in winter wheat. MON 37500 applied preemergence (PRE) or in fall postemergence (POST) provided better control of downy brome than when applied spring POST. MON 37500 at rates ranging from 19 to 33 g ai/ha applied PRE or fall POST controlled downy brome >85%. MON 37500 applied spring POST at 60 g/ha only suppressed growth of downy brome. Winter wheat was not visibly injured and maturity was not delayed by MON 37500 applied up to 60 g/ha at any of the application timings. Winter wheat yield responded positively to all MON 37500 treatments but PRE or fall POST applications usually resulted in greater yields than spring POST applications. Wheat yields progressively increased with increasing rates of MON 37500 up to 30–40 g/ha, above which yields tended to plateau or, in two instances, decline slightly. MON 37500 is an important new herbicide that should enable growers to better manage downy brome in winter wheat production systems.