“In this trial, napus varieties appear to be just as suited to straight cutting (as juncea). No matter the treatment, InVigor 5440 has the highest yield and lowest losses. That was consistent across all sites.”
As the time of harvest approaches, canola yield can be lost two ways — through pod drop and through seed shattering. To date the recommended practices for harvesting canola has been to swath. Each year, however, more and more farmers are choosing to forgo the extra pass through the field and straight cut the crop.
Swathing has its advantages, of course. It’s a great risk management tool against variable weather conditions, it accelerates dry-down and can make harvesting a variable field easier. But in a field with even maturity, low disease and weed levels and good plant density, straight cutting can save time while maintaining yield.
Traditionally, the biggest concern is that seed shattering losses are higher with straight cutting. Two products, UAP’s Pod-Stik and Brett Young’s Pod Ceal DC, claim to reduce seed shattering losses by coating the pods with a protective coating.
Chris Holzapfel, researcher at the Indian Head Agricultural Research Foundation, led a trial in 2009 to evaluate the two pod sealants’ effectiveness on reducing shattering losses in five varieties of canola. Indian Head was one of four Saskatchewan locations that ran the trial. The study also had plots at Scott, Swift Current and Melfort.
While there is still more work to be done, Holzapfel says the preliminary analysis is revealing. “First off, the data suggests that straight cutting was a viable harvesting choice at all sites,” he says, meaning that yields of the swathed treatments were not significantly lower than those of the straight-cut treatments. In fact, at Scott and Swift Current, straight cutting proved to be the best choice.
Across the board, however, the use of a pod sealant had no significant impact on minimizing crop losses. “This is only one year of the trial,” Holzapfel says. “We plan to run it again in 2010 and are looking to include at least one field-scale trial.” One year of data just isn’t enough to pass decisive judgment on a product’s effectiveness, he says. Nonetheless, Holzapfel advises that “there was no evidence in this study to suggest that pod sealants resulted in increased yields or reduced shattering losses relative to untreated canola.” Consequently, any growers who wish to try these products on their farms in 2010
Not surprisingly without significant yield differences between plots or a significant effect from the pod sealants, profitability was virtually unchanged between treatments. The one exception being at Swift Current and Scott, where the straight-cut treatment plots (both treated and untreated) did yield significantly more than the swathed plots.
are strongly encouraged to leave check strips and critically evaluate the products’ effectiveness for themselves.
VARIETY SELECTION MORE IMPORTANT
While pod sealants may not have had a major impact on shattering losses, variety selection did. Holzapfel and colleagues evaluated four napus and one juncea variety. “Juncea varieties are typically touted as better suited to straight cutting,” he says. The trial actually found, however, that napus varieties fared just fine. In fact, due to the lower yields, percentage seed yield losses of the juncea variety were higher than for any other varieties at some locations.
“In this trial, napus varieties appear to be just as suited to straight cutting,” Holzapfel says. “No matter the treatment, InVigor 5440 has the highest yield and lowest losses. That was consistent across all sites.”
Pod sealants do come with a cost for both product and application, so why no difference in profitability? “We assumed the same cost for swathing — $15 per acre — and applying pod sealants,” Holzapfel says. Also, he clarifies that while the study found no statistical difference in profitability, in real dollars there are subtle differences.
HARVEST CONDITIONS A KEY FACTOR
While there weren’t huge differences in yields between swathing and straight cutting, harvest conditions certainly played a role in total crop losses. In areas with a longer harvest season due to poor weather, such as at Melfort in 2009, swathing did appear to maintain yields better than straight cutting, proving that there is a time and a place for both practices.
“You’ve got to pick and choose your fields carefully,” Holzapfel says. Taking the crop at the optimal time is critical in maintaining yields, far more critical than any product or specific header type. “With a lot of acres to cover, it’s just not practical to expect to straight cut everything,” he says. Some of the plots were left in the field two weeks to a month after the optimal harvest window to see the effect of poor harvest timing. The losses — in all cases — were much higher than when the crop was harvested at the optimal time.
Lyndsey Smith is a Grainews field editor based in Lumsden, Sask. Email her at [email protected]