Using pod shatter resistance in oilseed rape to positively manage its harvesting could add as much to the crop’s bottom line as the best disease control this season. What’s more, it need not cost anything more than a little extra care and attention.
This is the advice of East Midlands-based Bayer commercial technical manager, Ben Frost who stresses that, at harvest values of around £650/t, maximising both OSR yield and oil content by good harvest management will be especially rewarding.
“Each day of seed filling lost is estimated to reduce seed yield by 1-2% and most oil is accumulated during the second half of the period,” he points out. “This puts a huge premium on actively using the pod shatter resistance in so many of today’s hybrids to avoid unnecessarily early desiccation.
“Conservatively, giving a typical 3.5t/ha crop just five days more before going-in with the Roundup (glyphosate) could mean an additional 0.25t/ha in the tank. That’s an extra £175/ha at current rapeseed prices before even thinking about bonuses which will also be much higher this season.”
Pre-harvest glyphosate is particularly valuable in drying down the most productive thick-stemmed, well-branched hybrid crops that have profited from stay-green agronomy, in Mr Frost’s experience. He also finds it very useful in evening-up crops that have suffered earlier CSFB larvae or pigeon damage.
“All our experience shows there is absolutely no advantage in spraying before rapeseed moisture levels drop below 30%,” he warns. “Rather than bringing the harvest forward, desiccating too early will just mean the crop takes longer to dry down. “As well as its impact on yield and oil, this can also significantly add to red seed problems.”
So, what does approach does Mr Frost recommend this season?
Well, first and foremost, he underlines the fundamental importance of assessing crops for ripeness very carefully, stressing the necessity of getting well into the field to sample pods at random from truly representative areas, rather than just from headlands or tramlines.
He urges growers to apply proven Roundup spray timing guidelines (see panel) to the area of their canopies bearing the lion’s share of the yield rather than the main raceme.
Then, when the right degree of seed colour change is found, he suggests waiting another five days before actually desiccating pod shatter resistant varieties.
“Patience is a huge virtue here,” he insists. “The extra time will be invaluable in building yield and oil from the less mature pods while the shatter resistance will minimise the risk of seed-shedding from fully ripe ones up to and at combining.
“Even the best Dekalb shatter resistance won’t completely protect a crop from heavy hail damage just ahead of combining, of course. But farm experience shows it can dramatically reduce losses here, making the difference between a decent crop and one that is virtually a write-off.
“Pod stickers aren’t strictly necessary with today’s shatter resistant varieties,” adds Mr Frost. “They cost so little, though, that any extra protection they may give is likely to be worthwhile at this season’s crop values.
“Despite the cost of diesel, I always advise applying stickers when the pods are still green, a good two weeks before the Roundup rather than with it. That way you get the greatest all-round protection – especially from any physical damage along the tramlines during desiccation.”
For the most reliable desiccation activity under the challenges of heavily-waxed, senescing canopies and today’s weather uncertainty, Mr Frost is adamant about the formulation benefits of modern glyphosates like Roundup Flex and PowerMax.
In addition to their greater overall efficacy, he sees their proven dry weather activity, great rainfastness and drift-minimising properties of particular value here.
“A good pre-harvest glyphosate is also an excellent way of dealing with the substantial grassweed populations that can easily escape notice in the base of OSR and go on to cause extra headaches and expense in following wheat crops,” he notes.
“The best pre-harvest spraying practice will pay dividends in targeting both the rape plants and their weed understoreys. Medium-coarse sprays are essential, together with water volumes, pressures and boom and nozzle settings that give thorough canopy coverage and penetration. Keep your spraying speed down and, in hot weather, spray early in the day for the most consistent uptake.“
“A 3.5t/ha crop will be worth almost £2500/ha this harvest. So, it will really pay to get the final stages of its management spot on. Especially so, with every 0.1t/ha you add putting more than £70/ha straight on the bottom line.”
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