13 August 1999

Match stubble work to brome type, says MRS

Beating brome grasses

demands a good

understanding of the weed. Here Andrew Blake and

Andrew Swallow examine

some of the latest

developments

KNOW which brome species you are trying to control when planning post-harvest cultivations for winter cereals after cereals, advises Morley Research Station director Jim Orson.

HGCA-funded research shows barren brome and meadow and soft brome need different approaches.

Sterile brome usually germinates quickly after harvest if covered by a shallow layer of moist soil or a thick layer of chopped straw. "So, even in dry autumns, we recommend shallow cultivation immediately after harvest where no-plough tillage is practised."

But where the weed is a particular problem ploughing is still the best option, and in those cases there is little benefit in stubble cultivation, he says.

Where meadow and soft brome are the targets, cultivation is the main option, but should be delayed, the HGCA work suggests. "If possible avoid cultivating for four weeks after harvest where you see significant numbers of seeds shedding on to the soil surface," says Mr Orson. "Weathering, and especially heat, shortens their dormancy making delayed sowing a more successful control technique. But straw and chaff must be evenly spread."

Meadow and soft brome are much harder to control with herbicides than sterile brome. But sulfosulfuron, sold as Monitor in Ireland but not yet available in the UK, is effective, he notes. "It is absolute ginger on them, but less good on sterile brome and if approved here will only be for use in wheat."

Ploughing should aim to bury brome seeds at least 12.5cm (5in) deep in well consolidated soil, and non-selective herbicide used pre-sowing to kill seedlings emerging from nearer the surface, he advises.

A sequence of Avadex (tri-allate), followed by isoproturon +/- cyanazine mixtures when the weeds have one to three leaves, is the best selective approach against sterile brome. But good control is rare, he says.

BROMECONTROL

&#8226 Match post-harvest tactics to species.

&#8226 Sterile: Shallow cultivate immediately in non-plough systems.

&#8226 Meadow & soft: Delay stubble work for four weeks.

&#8226 Plough at least 12.5cm (5in) deep.