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OSR yields and timing

Date Added: 25/06/2012


OSR yields could come down to a question of timing

 

 

Following an unpredictable spring of heat waves, drought, late frosts and record-breaking rainfall, oilseed rape growers will need to think carefully about when to apply glyphosate in preparation for this year's harvest.  That is the warning from Richard Elsdon, Technical Manager at United Oilseeds, who believes that the right crop preparation protocol could ensure yield increases of up to 5%.

This year's unpredictable weather pattern has given rise to the longest flowering period for oilseed rape in recent years and could give growers additional headaches as the summer harvest season approaches.  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 subsequently 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.

"This year pod production has taken place over of a period of 8 to 10 weeks instead of the more normal 6 to 8 weeks," Mr Elsdon explains.  "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 - for example, as a result of early glyphosate application - 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 4% 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," Mr Elsdon explains, "but this adds a cost and delay to the continuous crushing process."

Mr Elsdon warns that growers may be tempted to apply glyphosate later than usual, but should temper this judgement 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 5%," Mr Elsdon adds.  "With crop values - for growers who trade through United Oilseeds' carte blanche pool - exceeding £400 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."


  • United Oilseeds is the UK's only specialised oilseed rape marketing company.

  • United Oilseeds is a farmer-owned co-operative with a clear purpose to continually improve the profitability of its members by providing an independent, cost effective marketing service.

  • United Oilseeds has 3100 active members who trade their crops and purchase seed via the company.

  • Farmers can join United Oilseeds as lifetime members for a one-off fee of £15.



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