Harvest Aids For Uneven Crops
Fields with variable stages need to be scouted carefully to determine which stage will contribute most to overall yield. If later stages are the minority and the greatest yield contribution is from earliest stages, then maybe there is no need to hasten maturity.
If growers decided they need to spray to even out or dry down the crop, the choices are glyphosate or Reglone. Reglone is a contact herbicide (only kills what it contacts) and is 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 60 to 75% 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 napus canola to facilitate dry down of lodged canola crops. Efficacy will be maximized with higher water volumes (91 to 222 L per acre ground or 18 L per acre aerial). Growers using Reglone on canola to be straight combined take note: Reglone can significantly increase both pod shatter and pod drop if harvesting is delayed, so be prepared to combine as soon green seed and seed moisture have reached suitable levels.
Glyphosate is registered for pre-harvest perennial weed control in canola. If a field can be sprayed during the longer, warmer days in August, then glyphosate can accelerate crop dry down. However, applications in September (when days are shorter and tend to be cooler) should be made with perennial weed control as the main goal. Any benefit to crop dry down should be seen as a bonus because at this time of year it can take weeks to see green material dry down. If the canola is glyphosate tolerant, then obviously no crop dry down will occur. Glyphosate is to be applied when the majority of seeds within the pod are yellow to brown in colour which is at least 30% seed colour change (which corresponds to when seed moisture is less than 30%).
Source: Canola Council of Canada