2015-06-22   facebooktwitterrss

Don’t Dessiccate Rape Too Early, Growers Warned

Far too many oilseed rape growers are cutting their crop profitability markedly for absolutely no gain in harvest timing by desiccating too early, warns Hutchinson’s technical development director, Dr David Ellerton.

OSR pods at the correct 30% moisture stage for glyphosate desiccation

OSR pods at the correct 30% moisture stage for glyphosate desiccation

“Just like swathing, going in too early with the glyphosate will do more harm than good. With each day of seed filling lost known to reduce seed yield by 1-2%, a week represents a third to two thirds of a tonne in a 4.5 t/ha potential crop. Since most oil is accumulated during the second half of seed fill, earlier than ideal spraying can also seriously compromise oil content. Add in the extra impact of too many red seeds on sample quality and the cost of impatience can be even greater.

“All the more so as early spraying will not bring forward the harvest. It will just take longer for the crop to dry down. And in some cases I’ve seen it ‘freeze’ the crop rather than working with it to improve dry down

“Unless the weather is ideal for rapid, even ripening, effective glyphosate desiccation invariably allows earlier and more efficient combining than natural drying. And it’s invaluable in evening-up crops with the sort of variability we so often see these days. But it has to be done right.”

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

In this respect, he points out that at the traditional spray timing for conventional crops grown at relatively high plant populations and bearing most of 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 greatest yield, oil content and sample quality, spraying should be delayed until the bulk of the pods are sufficiently ripe,” advised Dave Ellerton. “This can be 7-10 days later than those on the main raceme. So it’s important to apply the Roundup spray timing guidelines to the area of your canopy bearing the lion’s share of the yield rather than the main raceme.

“For the fastest, most trouble-free and productive harvest it’s also important 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 after spraying under some conditions. Patience will again be a virtue here.

“Making a conscious effort not to desiccate or combine too early will definitely pay dividends,” he concluded. “Pod sealants and shatter resistant varieties can markedly reduce any extra risk of seed losses this may entail. And applying a quality glyphosate like Roundup Flex at the right rate with the correct 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.

Hutchinsons

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