Swathing later will increase yield because more of the later seeds in side branches will reach maturity and contribute to yield. CCC research from the early 2000s shows that canola fields swathed at 60% seed colour change (SCC) on the main stem can yield 8% more than fields swathed at 30% SCC. The yield difference could be even higher with lower plant populations because in stands with fewer larger plants, more of the yield will be in the side branches.
But what if harvest is moving slowing and the priority shifts from highest yield to just getting the crop in the bin?
Here are some considerations:
Swathed canola can be ready to combine earlier than standing canola. But swathing early does not mean combining early. Canola swathed green takes a lot longer to cure than canola swathed at 60% seed colour change. Whether growers swath a green crop now or wait a week, combining will likely occur around the same time. And by cutting early, the crop may not meet its yield and quality potential.
Pre-harvest sprays can speed up straight combining. Pre-harvest aids applied to canola left standing for straight combining will not speed-up crop maturity, but they (diquat/Reglone in particular) can speed up crop dry-down. What’s the difference between maturity and dry-down? Desiccants like diquat shut down the plant and basically STOP it from maturing, which can lock in high green seed levels and end the finishing opportunity for latest seeds if applied prematurely. Read more.
A scenario: A farmer has 3,000 acres of canola to harvest. In early September, some fields are at 10% SCC and some are at 40% SCC. The rest are in between those stages. The farmer wants to know whether to cut the 10% crops now knowing that he’ll sacrifice some yield, and cut the 40% SCC last knowing that when he gets around to those fields they may be at the perfect stage for highest yield.
The natural recommendation would be to swath the 40% SCC now. The timing isn’t ideal, but it’s better than the 10% crop. If seed maturity is advancing slowly with cooler temperatures, the 10% SCC crops may still be at only 20% SCC by the time the swather arrives. In that situation, can the farmer wait a little longer to cut that crop? If not waiting, those seeds that are not mature (greater than 40% seed moisture) will be small and probably still green IF they make it to the combine hopper at all. A large percentage of those green seeds will not make it to the combine hopper.
Another angle here is that green seeds may be ready to swath. SCC assessment can get tricky when we get into those cool holding patterns of fall.
For a few more considerations read “It’s September 9. Do I cut that green canola?” from a previous year.