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Early Ripening Varieties Ease Harvesting Pressure
Original Article published in FarmBusiness 5th June 2009
Minimising losses at harvest is imperative if growers are to achieve respectable yields. While the inclement weather of the past two seasons has made this a challenge, it has also highlighted the value of early ripening varieties and those with good pod characteristics.
Until recently, a variety's harvestability was defined by its lodging resistance and stem stiffness, while rape management primarily revolved around effective growth regulation and timely swathing.
While these considerations remain important to many, Monsanto technical specialist Manda Sansom points out that recent breeding and agronomic advances have given growers a host of valuable extra ways of ensuring minimum losses at harvest.
“With the development of low biomass varieties and the widespread adoption of Roundup as a harvest management tool, direct combining has become the norm,” she notes.
“Under these circumstances stem shortness and crop management have become particularly important considerations in variety selection, leading Castille and Excalibur to account for almost half of the current winter rape crop.
"The arrival of DK Secure as the first low biomass hybrid with the determinate semi-dwarf characteristic on the UK Recommended List offers greater harvest efficiency; not least for their extreme resistance to lodging," adds Ms Sansom.
“The fact that early-maturing, Excalibur can be harvested around seven days ahead of most varieties and up to two weeks ahead of others without yield penalty is another clear reason for the recent surge in the variety’s popularity.
“Being able to start harvest a week earlier is a real boon in relieving pressure on staff and machines, as well as cutting harvest risk.
"It also gives more leeway for subsequent wheat harvesting and it means more time for better grass weed and volunteer control, as well as seedbed preparation ahead of the next wheat crop," points out Ms Sansom.
“Add to this the pod shatter resistance characteristics of Excalibur and you have a recipe for minimising header losses, especially if you combine this with effective timing of Roundup in the run up to harvest,” she adds
Ms Sansom stresses that high yielding crops with thicker, greener stems produced by modern OSR agronomy are in greater need of chemical management at harvest, but are also more amenable to it by virtue of their open, upright structure and greater resistance to lodging.
“Although HGCA trials have shown earlier-than-ideal glyphosate treatment has less effect on oil yield than earlier-than-ideal swathing, correct timing is vital if yields and oil contents are to be maximised,” she advises.
“Aim to spray only when seed moisture has fallen to 30% or less, using the standard Roundup ripeness assessment
test because modern varieties can differ markedly in their seed ripeness at an identical pod colour.
"Depending on the weather, the stalks will be dry enough to start harvesting around 14-21 days after spraying.
“In addition to opening-up the combine harvester's concave to within a couple of stops of its maximum, specialists from Claas recommend increasing the wind setting to keep the sieve box in motion and setting the straw chopper blades to minimum to save on horsepower and avoid gumming-up the spreader to booset efficiency rates," Ms Sansom concludes.
The official trial system often fails to fully reflect these points
For example, many hybrids are larger than the line varieties and growers should adjust their plant population, nitrogen application and growth regulator use to account for this.