A diverse management strategy over two or three years, with late season control of survivors, is the key to depletion of the brome grass seedbank.

Key points

• Brome grass is common to southern Australian cropping systems in low, medium and high-rainfall regions. It is favoured by reduced tillage and increased intensity of cropping
• The common species, great brome (Bromus diandrus) and rigid brome (B. rigidus), are very similar and cannot be distinguished in the field. There is considerable variation between populations of each species in terms of seed dormancy and emergence times
• Staggered and delayed emergence during the season make it impossible to control this species with pre or post-emergent herbicide use alone. A diverse range of weed control tactics, including seed-set control, is usually required to drive the seedbank to low levels
• Optimal control is achieved in break crops or by growing herbicidetolerant cereals, as these rotations allow use of more effective in-crop herbicide options
• Herbicide resistance is still rare over most of Australia, although there are regions with increasing resistance issues. Self-pollination ensures there is little opportunity for resistance spread by pollen flow. In the areas where resistance remains uncommon, make sure resistant seeds are not introduced to the farm or spread from one paddock to another on the same farm
• Depending on the density of the initial brome grass population, aim for three to four years of effective control to deplete the seedbank