Canola swath timing tips
By Canola Council of Canada
Sept. 3, 2015 - Swathing when most seeds on the main stem look like those in the photo to the left — with at least some colour — will mean more of the seed on side branches will be mature enough to contribute to yield. Cutting too early sacrifices a lot of side branch yield. The ideal is to swath at 60 per cent seed colour change on the main stem.
Early swathing leaves yield on the table. The optimal swath timing for canola yield and quality is when 60% of seeds on the main stem are showing some colour change. Seed colour change (SCC) is considered any amount of yellow or brown on the seed. This increases crop yield because side branches have longer to fill and average seed size for the whole plant is larger. Cutting earlier does not give side branches time to fully mature, reducing yield. Click here for graph, podcast and two videos.
Swathing ahead of a frost forecast. With light frost in the forecast, crop left standing will still have a chance to mature further and yield more. A heavy frost will lock in high green counts and likely increase yield loss with pod splitting and pod drop. Swathing before the heavy frost event may prevent this green lock, but the crop needs to dry down to a seed moisture level of 20% or less. This can take 3 good drying days, so swathing has to occur at least 3 days before the frost to achieve this benefit. Click here for exceptions
Cut timing must meet pre-harvest intervals. Lygus are still around in some fields. They have difficulty penetrating mature leathery pods, so damage may be minimal in most crops. For those crops that are sprayed, keep in mind that the product used will have a required pre-harvest interval, which is the required time between spraying and cutting of the crop. Use the tool here to see the pre-harvest interval for each product.
How to tell when uneven crop is ready to swath? If earliest plants in a field show obvious signs of maturity, with lots of seed colour change on the main stem, then cut the first two rounds. Two full rounds give a good impression of the state of the whole field. And the cleared space makes it much easier to quickly check a number of plants in a few areas — including the back of the field — for seed colour change. Click here for more decision tips.
Sun-scalded pods may not be mature. Pods darkened by the sun may look mature, but open them up and check the seeds inside. Look for seed colour change or, at a minimum, give seeds the "firm to roll" test. If green seeds are firm and roll between thumb and forefinger with mushing, they should mature into harvestable seeds.