As the calendar progresses and the risk of fall frost nears, it may be tempting to swath earlier than optimal. Growers must ensure that seed colour change is occurring when assessing the proper time to swath. Do not use plant or pod colour to gauge proper timing because some pods will appear ripe on the outside before the seeds are mature. Some varieties will show pod colour change long before the seeds do, while the opposite is true of other varieties. This year, significant yield may be contributed by side branches so seed colour change needs to be scouted on the side branches as well as the main stem. Open up pods and look at the colour of the seeds to accurately assess swathing timing. Research indicates that the optimum stage to swath for both yield and quality is up to an average of 60% seed colour change (SCC).
However, for growers faced with uneven maturity within fields, it may not be possible to swath all the crop in the 50-60% SCC window. In situations where uneven maturity is the problem, the best approach is to swath when the most mature plants are close to 60% SCC, provided that the least mature plants are showing some seed colour change at the base of the main stem and that seeds in the upper pods (and branches) are dark green and firm (if maturity varies more than this consult the link regarding multi stage crops below). This will minimize yield loss from seed shrinkage and improve the odds that the seed will cure, although it will likely take longer and may require some more moist conditions. Swathing prior to 15 to 20% seed colour change will likely reduce some yield potential, and could contribute to green seed issues under hot and/or dry conditions.
More information is available on the “Canola Time of Swathing Guide” at the following link:
More information on harvesting a multi-stage crop is available at the following link: Harvesting Mult-Stage Crop