How green can you swath canola?

[RENO]

I am first time canola grower and am wondering how green I can swath without affecting the grade. Greatly appreciate resposes.

[poorboy]

It depends on how quick the straw dry's down. I have swathed it with 10-20% color change and had lots of heat and it took 4-5 weeks in the swath to get the green count down to 2%, and other times it is wetter in the week after it is cut and it is ready to combine in 1-2 weeks with 1% green seed.

In my experience if frost is not a concern, it is better to wait an extra week and get to 50% color change and you will thresh it still a week to 2 weeks sooner than the canola that is cut at 10% color change.

If worried about frost, then the ideal time may be different.

[mhartman]

Gauging the correct time to swath canola is more important and difficult than with cereals. Swathing at the optimum stage will reduce shattering compared to late swathing, and reduce green seed content and increase seed size/oil content compared to early swathing.

Main stem pods from different parts of the field should be examined for maturity and thus readiness for swathing. Uneven ripening over the field often complicates the swathing assessment – hilltops are often much riper than low spots. Seed ripening varies on the same plant -- pods at the bottom of the plant are formed first and will mature before pods higher up or on side branches.

Seed color is more important than the overall field, straw or pod color when gauging the optimum time to swath. When the seeds reach 35 to 40 % moisture they turn from green to light yellow, reddish brown, or brown, depending on the cultivar. In the fall in western Canada, ripening seeds lose moisture at about 1 to 3 % moisture per day, depending on the weather.

The optimum stage to swath canola is when 30-60% of the seeds have color change. Small patches of color change are counted as changed. When seeds in the bottom pods have turned color, seeds in the pods near the top of the main stem and on side branches are green but filled or nearly filled. However, these later formed seeds should be checked to ensure they are firm and will roll, not squash, when pressed between the thumb and forefinger. Canola seed does not continue to fill once swathed – they will only dry down.

Growers with many canola fields should start swathing canola at 30% seed color change in order to finish their last field before surpassing 60% seed color change. Very hot and dry, windy weather during and after swathing may prematurely halt chlorophyll clearing in green seed due to low seed moisture, and in such weather swathing should be delayed to the end of the swathing window. Thin canola stands have more side branches that mature later – thus swathing should also be delayed in such situations.

On the other hand, if conditions are cool and a frost or snow storm is forecast, swathing as early as 10% seed color change could be justified to minimize green seed or harvest difficulties. In order to reduce green seed due to frost, the field must be swathed about 3 days prior to the frost.
Green seed caused by frost damage will NOT degreen in the swath, whereas green seed caused by rapid drydown during hot weather may degreen if rain rewets the seeds above 20% moisture.
Canola fields with significant pod spotting due to Alternaria also should be swathed early to reduce shatter losses and pod drop. Unusually heavy, late infestations by flea beetles or lygus bugs may also benefit from early swathing rather than spraying insecticide beyond the allowable pre-harvest window.