Timing-related yield increases in winter wheat after applications of MON37500 herbicide to control Barren Brome (Bromus sterilis)

Twenty small plot replicated trials were sprayed in Northern Europe between 1996 and 1999, in order to assess the impact on the control of Barren Brome (Bromus sterilis) and yields of winter wheat. The herbicide used was MON37500, a sulfonylurea herbicide which checks the growth of Barren Brome, reducing weed competition with the crop. Applications of herbicide were made in the Spring, from late tillering to stem extension of the crop. Results from this series of trials indicate that removal of competition from Barren Brome is most advantageous when herbicide application is made early in the Spring. Weed control at harvest, measured by biomass reduction, was not significantly better from early or late sprays, but yield increases were more often greater from earlier applications. Untreated yields and the yield increase associated with herbicide treatment were both negatively correlated with weed panicle numbers at harvest.