Generally producers are waiting for adequate seed colour change before swathing but there have been reports of producers cutting fields too green. Avoid the urge to swath too early, especially under high temperatures (upper 20’s to 30’s or more). If hot, windy conditions continue, rapid dry-down of the plant material will not allow for proper curing which could lead to situations of elevated green seed. Slower dry down aids the curing process, which is important for reducing the chance for green seed issues. The optimum time to swath is when the majority of the crop has achieved 60% seed colour change. Waiting for this stage allows the crop to enter the dry down phase while still standing and does not require as much curing in the swath. Growers with large acreages to cover may need to start swathing earlier. The best fields to start cutting before 60% seed colour change are those that are most uniform in maturity with a dense stand (not a lot of side branching). Waiting for at least 30% SCC will capture most of the yield potential because the bulk of the seed will be past physiological maturity and be entering the dry down phase. Growers should avoid swathing during the hottest part of the day to minimize shattering of mature pods and slow dry down of less mature ones. This is particularly important in the situations described above. Swathing in the late evening through early morning hours when moisture levels are higher also helps in situations where hail or insect damage is present, or diseases have predisposed the plants to shattering.
More information is available in the “Canola Time of Swathing Guide” at the following link: