Light conversion from OSR green leaf
Good autumn establishment has seen oilseed rape crops come through the winter well and evaded the effects of pest pressures for both the northern Lincolnshire and southern Berkshire farms of Sutton Estates, managed by Chris Baylis.
Chris, below, reported the big leaves of his DK Extrovert in the ground had seen some larger GAI recoding this season, with an average of 1.0 in Lincolnshire, and slightly ahead in Berkshire at 1.25, with crops drilled in 500 mm bands.
With the strong growth, March N applications ranged from 60-80 kg N/ha, depending on GAI. “The first application is aimed at canopy retention, leaving the final 120 kg/N/ha to be applied later, typically at yellow bud, or as late as we dare,” he added.
He pointed out that canopy management, with a combination of nutrition and PGR, is aimed to develop a uniform crop coming into flower, which can minimise the impact of pollen beetle and, wherever possible, avoid the need to control.
To make the most of this green leaf area Syngenta Field Technical Manager, James Southgate, highlighted OSR relies entirely on photosynthesis post-flowering to put on yield.
“Unlike cereals, there is no evidence that OSR can move carbohydrate energy reserves around the plant to drive oilseed yield, which makes green leaf area so essential,” he advised iOSR growers.
“Low radiation levels in May and June last year coincided with pod fill; it was simply too dull for pods to reach their full potential and possibly teh key reason for disappointing yields.”
So in the field, it’s the green leaf growers should look to preserve, he said.
“An application of Amistar at yellow bud to early flowering is the best timing to prolong the green leaf area,” he advocated.
In ADAS trials the GAI in an OSR crop was prolonged by as much as 0.5 from the end of flowering for up to a month from 1.0 l/ha of Amistar at flowering, he reported.
James pointed out that, more recently, Sclerotinia pressure has tended to increase later in the season, with applications at mid flowering giving the best disease control.
“The greening effect still happens at the later timing, although to a lesser degree. Field trials have shown the improved plant health it brings also helps combat the effects of Verticillium wilt,” he reported.
“Even in a year with low Sclerotinia incidence, you still get the economic yield benefit from higher yield and greater oil content of seed from an Amistar application,” he added.