East Anglia: Weather ‘poses major challenges’ to region’s oilsea growers

An exceptional and unpredictable spring of heatwaves, drought, late frosts and record-breaking rainfall poses major challenges to oilseed growers across the eastern counties, an expert has warned.

The impact on oilseed rape yields could come down to a question of timing and farmers need to think carefully about when to apply glyphosate in preparation for this year’s harvest.

Richard Elsdon, technical manager at United Oilseeds, which has more than 3,100 members, suggests that the right crop preparation protocol could ensure yield increases of up to 5pc.

“With a harvest crop value of �345 per tonne, plus 10pc oil premiums giving a total value of �379.50 per tonne, it is well worth investing in a little extra time and care in the run-up to harvest to ensure that yields and oil content are protected,” he added.

The unpredictable weather pattern gave rise to the longest flowering period for oilseed rape in recent years, which could give growers additional headaches as the summer harvest season approaches.

Then the unusually hot spell in the middle of March marked the start of a relatively early beginning for petal growth, but further crop development was halted by a period of unseasonably cold weather at the end of March and the wettest April on record.

May’s heightened temperatures extended the flowering period, leading to crops of varying states of maturity, making it difficult for growers to know when to apply their pre-harvest treatment of glyphosate.

Most Read

“This year pod production has taken place over of a period of eight to 10 weeks instead of the more normal six to eight weeks,” said Mr Elsdon.

“It therefore follows that we have seen an exaggerated variation between upper and lower seed pod maturity. While some plants have already produced full seed pods, others are still in full bloom with relatively few mature pods.

“Growers will therefore need to ensure that they apply glyphosate at the optimum time as early application could lead to yield losses due to a high percentage of immature pods. On the other hand, late application could result in crops being rejected due to uneven ripening and sub-standard seed quality, as well as excessive seed losses as a result of pod shatter.”

The oil in rapeseed pods accumulates during the latter half of the seed filling period, so any shortening of this stage will have a detrimental effect on oil yields and result in diminished returns for the grower.

In addition, oil crushers demand seed which is of a “good merchantable quality” and will reject crops that contain more than 4pc immature seed: seeds should have a bright yellow, oil-rich inner.

A green seed inner indicates an excessive amount of chlorophyll, which will contaminate the oil when the crop is crushed. “Chlorophyll can be removed but this adds a cost and delay to the continuous crushing process,” he added.

Mr Elsdon warned that growers may be tempted to apply glyphosate later than usual, but should temper this judgment against the risk of pod shatter. Growers are also advised to consider using a co-polymer such as Podstik or Arrest, to enable crops to dry-down at minimal risk of seed loss.

“Trials have shown that the use of a co-polymer which holds the sides of the pod together can result in yield increases of up to 5pc,” he added.