What are the risks of swathing too early?

August 31, 2011 - Issue 22

Harvest

Some growers anxious about the calendar and the typical date of first killing frost are swathing canola early, at around 10-15% seed color change. At this stage, many seeds on the side branches may be watery and translucent. If this represents 30% of seeds, for example, growers must recognize that early swathing could mean sacrificing a large proportion of that yield — regardless whether the frost comes or not.

Most of those watery and translucent seeds will not fill sufficiently in the swath to make it to the bin, and if they do, they may contribute to green seed issues. Warmer and/or drier conditions following swathing will increase the losses due to more rapid dry down of the swaths.

In warm dry conditions, canola matures quickly and seed color change can increase by 10 percentage points in 3 days or less. Ideally growers should wait at least until all seeds on side branches are firm and roll between finger and thumb before swathing.

Check the long-range forecast. Light frosts to 0 or -1 C will likely have minimal effect on overall yield and quality of canola. If no frost is forecast, then waiting a little longer to swath should improve yield and possibly quality.

Multi-stage crops. Judging when to swath multi-stage crops can be trickier. If the field has distinct late and early parts, the two parts could be swathed at different times. If not, then make the swath decision based on which plants are likely to contribute most to yield. Be realistic based on the calendar date. If part of the field is at 50-60% seed color change while another hail damaged part of the field is still flowering, the swathing decision should perhaps be based on what’s best for the plants that are mature. There is no ‘perfect’ time to swath these uneven crops, so at some point you have to decide that this is the best time for the majority of the plants in the field with the least negative impact possible on the rest — the biggest yield with the least losses.

Harvest webinar. Please join the Canola Council of Canada for a presentation from Les Hill of Prairie Agricultural Machinery Institute on minimizing seed loss while maintaining harvesting efficiency during combining. Click here to view a recording.

Canola Watch