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Winter oilseed rape establishment is good across the UK – despite later sowing than many growers planned, suggests a survey. Big rise in oilseed rape area, confirms annual grower poll

• 10% rise in oilseed rape area

• Flea beetle threat on decline

• Modern hybrids perform well

Winter oilseed rape establishment is good across the UK – despite later sowing than many growers planned, suggests a survey.

A marked increase in plantings confirmed by the late October survey suggests a 10% increase in the area of crop coming into spring 2023, according to the fourth annual Dekalb national establishment poll.

Reports from over 230 growers responsible for 25,000ha of oilseed rape across the UK’s main arable areas suggest that little more than 6% of this year’s crop is likely to be the subject of breeders’ establishment scheme claims for failure.

More than 75% of growers rate this season’s crop at 7 or more for establishment on the poll’s standard 0-10 scale, with just 8% rated less than 5.

“Barring any major winter or early spring issues, these findings point to an overall crop survival to flowering similar to the past two years at around 90% of plantings,” says Bayer seed campaign manager and poll co-ordinator Lizzie Carr-Archer.

“This is a vast improvement on the 67% survival to spring we recorded in the last particularly challenging establishment season of 2019/20. And it’s certainly not what large numbers of growers were expecting after such a bone-dry summer.”

Soil moisture

With almost two thirds of growers reporting very or fairly dry conditions at sowing – and only just over a third considering them at least reasonable – this year’s poll shows moisture levels at sowing were actually worse than 2019.

Together with sowing delays prompted by the very dry conditions, this left many crops particularly open to the normal late August/early September cabbage stem flea beetle challenge.

Although higher than the past two years, flea beetle pressure was well below the level of 2019, with only just over 20% of growers reporting substantial and intense challenges from the pest compared to more than 50% three seasons ago.

Over 80% of growers reported receiving enough rainfall between sowing and late-October. This almost certainly accounts for the very much better position of the current crop going into winter.

“As ever, our study shows considerable differences between the regions in flea beetle pressures and moisture conditions both at and after sowing,” says Ms Carr-Archer.

“Even those areas faring worst in terms of pest pressure and dryness, though, have markedly better average establishment scores than 2019.”

Trend reversed

Unsurprisingly perhaps, the much drier August led to a clear reversal of the trend to earlier drilling recorded over the past three seasons, with nearly 60% of crops sown after 20 August against 45% in 2021.

“Unlike recent years too, it also meant that earlier sown crops didn’t necessarily establish better than those going in at a more traditional late-August timing, despite what continue to be higher flea beetle pressures at this time.

“This reinforces the importance of the balance between pest pressure and moisture conditions in determining rape establishment. Our latest data show flea beetle pressure continues to have a greater impact on establishment than soil moisture.

“Crucially too, they underline that the real clincher in moisture terms is rainfall after sowing rather than conditions at drilling. The difference in average establishment score between the extremes here was almost twice that between the extremes of moisture at sowing.”

With drilling conditions so dry, Ms Carr-archer says it is no surprise that this year’s poll shows few overall differences in establishment success either between different establishment regimes or variety types.

But a noticeable gap was evident between hybrids and pure line varieties where crops were under the particular challenge of less than adequate rainfall after sowing. Together with lower levels of re-drilling, this underlines the benefits of modern hybrids.

“Greater flea beetle pressures this season inevitably led to greater insecticide use at establishment than in recent years,” says Ms Carr-Archer. “Even so, it’s encouraging to more growers deliberately avoiding insecticide spraying.

“This season’s poll gives particular confidence to those not letting the very dry early autumn put them off sticking with or increasing their winter OSR growing for 2023 – although there’s a lot of water to go under the bridge yet.”

Having said that, the importance of establishment quality to crop performance and the extent to which later sowing reduces the flea beetle threat means there is likely to be a substantial year-on-year increase in the crop area going to harvest.

“After all, even in the particularly damaging CSFB season of 2019/20 growers only recorded an average crop loss of around 6% between early spring and harvest,” says Ms Carr-Archer.