Arable News

  • Written by: Farmers Guide
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Dont desiccate OSR to early, growers warned

Far too many oilseedrape growers are cutting their crop profitability markedly for absolutely nogain in harvest timing by desiccating too early, warns Hutchinsons technicaldevelopment director, Dr David Ellerton.

In my experience, workload pressures and the overwhelming desire to getharvesting spurred on, no doubt, by neighbours out with the sprayer, not tomention eagerness to apply a pod sticker means crops are often being sprayedat least a week before they should be, he insisted. 

Just like swathing, going in too early with the glyphosate will do more harmthan good. With each day of seed filling lost known to reduce seed yield by1-2%, a week represents a third to two thirds of a tonne in a 4.5 t/hapotential crop. Since most oil is accumulated during the second half of seedfill, earlier than ideal spraying can also seriously compromise oil content. Addin the extra impact of too many red seeds on sample quality and the cost ofimpatience can be even greater.

All the more so as early spraying will not bring forward the harvest. It willjust take longer for the crop to dry down. And in some cases Ive seen itfreeze the crop rather than working with it to improve dry down.

Unless the weatheris ideal for rapid, even ripening, effective glyphosate desiccation invariablyallows earlier and more efficient combining than natural drying. And itsinvaluable in evening-up crops with the sort of variability we so often seethese days. But it has to be done right.

Dr Ellerton sees modern Roundup formulations providing valuable extra harvestmanagement reliability under the extreme challenge of desiccating thick-stemmedOSR canopies; especially those that have profited from stay-green agronomy.But, with margins as tight as they are today, he is adamant that better timedspraying is essential to avoid unnecessary waste in yield or quality.

In this respect, he points out that at the traditional spray timing forconventional crops grown at relatively high plant populations and bearing mostof their yield on the main raceme, more than a third of the pods in well-structured,modern, hybrid OSR canopies may be immature.

For the greatestyield, oil content and sample quality, spraying should be delayed until the bulkof the pods are sufficiently ripe, advised Dave Ellerton. This can be 7-10days later than those on the main raceme. So its important to apply theRoundup spray timing guidelines (panel) to the area of your canopy bearing thelions share of the yield rather than the main raceme.

For the fastest, most trouble-free and productive harvest its alsoimportant to start combining only once stems as well as pods are fully fit.This fundamentally depends on the weather and may be two to three weeks afterspraying under some conditions. Patience will again be a virtue here.

Making a conscious effort not to desiccate or combine too early willdefinitely pay dividends, he concluded. Pod sealants and shatter resistantvarieties can markedly reduce any extra risk of seed losses this may entail. Andapplying a quality glyphosate like Roundup Flex at the right rate with thecorrect nozzles will ensure the most timely and complete crop drying.

Roundup OSR Harvest Management Guidelines

  • Select an area of the field representative of the crop.

  • Pick 20 pods from the part of the canopy bearing the bulk of the yield.

  • If at least two thirds of the seeds have changed from green to brown in at least
    15 pods, the earliest stage for spraying has been reached.

  • Repeat in other several areas of the field to check for consistency
    and spray within 4-7 days.


  • Written by: Farmers Guide
  • Posted:
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