Growers planting oilseed rape in rows 50cm or wider should consider seed rate in terms of seeds per metre row length rather than seeds/sq m, said ADAS’ Sarah Cook.

Trials growing the crop in 12, 24, 48 and 72cm rows at 10, 20 and 40 plants/sq m showed higher seed rates in wider rows caused inter-crop competition and reduced establishment, she said at the recent ADAS Boxworth open day.

“With 12cm rows the higher seed rates give a nice plant distribution, but in the wider rows they are too thick.”

Growers on 48-50cm rows should aim for a 6cm gap between plants, which equated to 8-15 plants per metre row length, said Dr Cook.

Weed control was also being considered in the trials and wider rows did appear to suffer from greater weed pressure, he noted. “But it shouldn’t be too much more difficult to control than the narrower spacings.”

This is the second year of trials and will be continued next year.