Harvest Risk Alert For High Biomass OSR Growers

May 30, 2003 - Thick stands of lush, well-forward crops and good 2002 market prospects add up to a notably high lodging and harvest difficulty risk for many oilseed rape growers this season, warns UAP technical director, Chris Bean. Which puts a particular premium on careful canopy management for all those with taller, higher biomass crops.

“Most winter OSR got away very well last autumn,” he pointed out. “In fact, almost every seed sown produced a plant. Over-wintering losses have been especially low too. So we’re coming into the spring with a lot of thick stands of relatively thin-stemmed crops.

“At the same time, healthy oilseed market prospects for the coming harvest mean everyone has a strong incentive to maximise yields with liberal amounts of spring nitrogen.

“All this adds up to a high UK-wide risk of lodging and harvesting difficulties. Especially so with around half the winter rape acreage down to inherently more vulnerable hybrids and other tall varieties like Winner.

Under these circumstances, Chris Bean advises all those not growing a low biomass, stiff-strawed variety to look to their canopy management laurels over the coming two months if they are to avoid yield losses, differential ripening, swathing and dessication difficulties, and grain sprouting problems this summer.

He does not suggest reigning-in on spring nitrogen, though, since this is likely to reduce yields far more than controlling canopy development. Instead, he recommends using one of the OSR fungicides known to have a growth regulation effect.

“We’ve had great success in PGR terms with both Caramba (metconazole) and Folicur (tebuconazole) applied to taller varieties at the late green bud stage in mid-late April at slightly higher rates than the 0.75litres/ha normally used for disease control,” reported Chris Bean.

“The fact that these triazoles offer significant economies over fungicides used at flowering, together with less crop damage and the possibility of not having to use a contractor with specialist high clearance equipment makes them an attractive disease control option. And increasing rates to 1.0 or 1.2 litres/ha will give a valuable stem shortening effect.

“High biomass rape growers should also consider the new fungicide, boscalid (Filan) which is supported with good data showing an anti-lodging effect from stem strengthening rather than shortening.

“Either approach will add to production costs,” Chris Bean conceded. “But in a year like this reducing the risk of problems with taller rapes will be essential if yield, quality and harvestability are not to be badly compromised.”