Fast drydown locks in green

Some elevators are reporting higher green seed counts. Swathing too early and swathing in hot and windy conditions are contributing factors in many cases. Cutting canola in hot conditions leads to rapid dry down and desiccation, which doesn’t give chlorophyll time to clear from immature seed. Waiting until less mature seed is at least firm to roll between thumb and forefinger will help minimize yield reductions from early swathing, but significant curing will still need to take place in the swath to remove green seed.

If growers feel they must swath at less than ideal seed color change, then wait until temperatures cool down in the evening. Night swathing gives the plant 4-5 hours to shut down slowly, and nights are usually more humid, cooler and less windy, providing more moisture for chlorophyll clearing enzymes to function. The next day, plants in the interior and bottom of swaths will continue to be sheltered from warmest temperatures and from wind. With today’s larger swaths, the sheltering benefit of the windrow is that much greater.

Restarting the enzyme process. Enzymes to clear chlorophyll can restart when seed rehydrates to 20% moisture. (This applies only to green seed causes by premature desiccation, not to frost injury. Green locked in by seed damage from heavy frost is not likely to clear even with wet weather.) Moisture levels required to bring canola back to 20% can be more than expected. An inch of rain will not lift canola at 7-8% moisture anywhere close to 20%. Several days of heavy dew, high humidity and additional rain events may be required. These conditions can happen and at this stage of the season, growers have time to be patient with swathed canola.

Swathing early does not mean combining early. This is an important reminder. Canola swathed green can take a lot longer to cure than canola swathed at 50-60% seed color change. Whether growers swath a green crop now or wait a week, combining could occur around the same time. And by waiting to swath, the crop has a better chance of meeting its yield and quality potential.

Click here for tips on how to check green seed levels in swaths without starting the combine.