OSR variety development speeds should dictate sowing dates

Oilseed rape growers should tailor varieties more to specific sowing slots, Masstock trials suggests

The work, part of the Best of British Oilseeds Initiative, highlights clear differences in varieties’ development speeds.

Last autumn Lioness and Excalibur took 55 days to reach leaf four emergence. But Kadore sown at the same time took another week, noted the firm’s David Newton.

“This can make a big difference in terms of growth habit before winter and eventual canopy development.

“Sow the faster varieties too early and, like wheat, you can end up with over-proud growth, worse disease and reduced yield potential,” he said.

In the trials, this was particularly evident with Lioness from early August sowing.

Even after growth-checking autumn Caramba (metconazole) treatment the variety had started to extend and was 15cm (6in) tall before Christmas. This left it more vulnerable to winter kill and produced an over-thick spring canopy.

By contrast Kadore, initially quick to establish, was slower to develop and closer to the ground, leaving a safer, less leafy canopy going into winter and a more manageable crop structure in the spring.

The work is starting to provide a clear sowing date ‘pecking order’, said Mr Newton, hybrids having the vigour to cope with later drilling in difficult conditions.

Safe early drilling varieties include Kadore and ES Astrid, while Excalibur and Lioness are more suited to late August or September sowing.