Control of Black-grass (Alopecurus myosuroides) and Barren Brome (Bromus sterilis) in rotational set-aside and the prevention of viable seed return using a new formulation of glyphosate.

Abstract

Since their use was first permitted on rotational set-aside in the 1993/94 cropping year, glyphosate-based herbicides have proved to be the most widely used method of weed control: Trials have been carried out over three years to investigate the effect of dose and timing on annual grass weed control, using a new glyphosate formulation with improved safety characteristics. Later applications (late May/June) gave better control of black-grass (Alopecurus myosuroides) and barren brome (Bromus sterilis) than earlier (late April/early May) sprays, in terms of both foliage kill and viable seed production, although more biomass was produced. Early sprays reduced biomass but viable seed was produced from secondary regrowth. A sequential treatment programme controlled both biomass and viable seed production effectively. It was found that spraying black-grass after the time at which potentially viable seed is present on the plant still resulted in complete control, whereas cutting at this time would have returned viable seed to the soil.