Swathing early before the recommended 50 to 60% seed colour change in the high temperatures occurring lately will not necessarily mean earlier combining. Under hot, dry conditions crop dry down can occur quickly (drop below 10% moisture) but not crop curing (seed maturation and removal of chlorophyll). Fields that are swathed early (e.g. 20 or 30% seed colour change) and/or swathed during the heat of the day will not cure as quickly as dry down occurs. Curing may take as long as two to three weeks in these fields cut on the early side. In fact, some fields may require additional moisture (rain) in order to re-hydrate the swath and facilitate curing. In southern Alberta, irrigation has been used post-swathing in some instances to help cure the crop. Click here for more information on rate of crop dry down under different weather conditions. If fields must be cut early (large acreage base) then cut at night to help reduce the rate of swath dry down and hence the potential for locking in the chlorophyll. Click here for more specific swath timing information from Canola Council agronomist Doug Moisey.
Source: Canola Council