Glyphosate
Glyphosate is registered for pre-harvest perennial weed control in canola. Glyphosate is to be applied when the majority of seeds are yellow to brown in colour and seed moisture is less than 30%. Applications made even slightly before the 30% moisture stage (physiological maturity) greatly increase the risk of excessive glyphosate residue in the seed. Canola is very efficient at moving glyphosate or other systemic compounds into the grain prior to physiological maturity. Excessive pesticide residues in the grain can result in export problems.
Some growers who straight combine canola that is not a glyphosate tolerant variety will apply glyphosate to even out the crop for easier harvest. When using glyphosate in this fashion, make sure a very minor portion of the field is immature for the reasons indicated above.
The rate of drydown with preharvest glyphosate is heavily dependent on environmental conditions, so weed control should still be the main goal. Glyphosate will not hasten crop maturity.
Heat LQ
Heat LQ is now registered and has all MRLs in place for pre-harvest use on canola. Heat LQ (Group 14 saflufenacil) has contact activity (like Reglone), but also is translocated (like glyphosate). It fits with any canola herbicide system, including glyphosate-tolerant varieties.
The application timing is 60-75% seed colour change. The pre-harvest interval is three days. Heat LQ can be used alone or in a tank mix with glyphosate.
Alone: When applied as a stand alone with Merge adjuvant at 400 ml/ac, BASF recommends high water volumes for good coverage. Treat it more like a desiccant.
With glyphosate: BASF recommends growers treat it as they would the straight glyphosate application. The benefit to the canola producer is more rapid dry down of crop and weeds over glyphosate alone while still maintaining the perennial weed control of glyphosate. Merge is still recommended with the tank mix.
Reglone
If desiccation alone is the goal, Reglone is a contact herbicide registered in canola to dry immature green material to facilitate harvest. Reglone does not hasten crop maturity. It shuts the plant down quickly and basically STOPS it from maturing, which can lock in high green seed levels if applied prematurely. The recommended timing for application on canola is when 80-90% of the seed has turned brown, which is past the stage when swathing would typically be recommended. Applying Reglone earlier may result in higher green seed. The label indicates that it should be only applied to B. napus canola to facilitate dry down of lodged canola crops. Efficacy will be maximized with the highest water volumes feasible (minimum 91 up to 222 L per acre ground or 18 L per acre aerial).
Source : AlbertaCanola