Green seed in canola can be a problem. Every year we have fields that need to be monitored at combining time. Green seed causes grade reductions (which results in lower prices) and can cause heating in storage through the winter.
Reducing green seed in canola starts in the spring. Selecting the right variety and setting up the proper fertility program reduces the likelihood of green seed in the fall. Picking an appropriate maturity for the canola variety in your field is critical. Proper fertility will reduces maturity requirements. Taking care of these issues in the spring will give the canola crop a chance to finish the growing season as healthy, mature plants.
In the fall, the green will leave the canola seed if the weather conditions are right and the swathing operation is done properly. Having the plant mature naturally will eliminate green count with canola seed. Swathing the canola crop at 60 % seed color change on the main stem will eliminate green seed counts. Swathing earlier can lead to green being locked into a canola seed especially if hot weather is in the forecast. Swathing canola when the temperatures are above 25 degrees Celsius can look green into a canola seed. Never swath canola in extreme heat.
Frost can lock green color into canola seed. Swathing a canola crop a couple of days before a frost will help reduce the impact of the frost on canola seed. Care must be taken when doing this because swathing too early can reduce yields in canola. Seeds can shrivel because they did not have enough moisture in the plant to survive the natural drying process.
Canola seed needs to have 20 % moisture in the seed for green chlorophyll to be taken out. An enzyme required to remove green needs this moisture to be active. If the moisture is not present, canola will not remove green from the seeds. This is why producers talk about needing a rain to take out the green from the seeds. If the canola is dry, it has to be re-wetted by a rain to bring the moisture back to 20 %. Once that moisture is attained, the green chlorophyll will start to leave the seed.
Waiting for green to leave canola seed is a good idea when the seed moisture is high. If a canola sample is above 10 % moisture, it may be worth waiting for a couple of days to see if the green count will go down in a canola sample. When the moisture of a combined sample drops below 10 %, it is unlikely that the green count in the sample will be reduced. The 20 % moisture required for the seed to take chlorophyll out of any seed will not likely be present, so the process will stop until the crop is re-wetted with rainfall.
In a perfect year, green seed is not an issue in canola. We very seldom have the perfect year, so manage your canola to reduce green and put more dollars in your pocket.
By Dave Cubbon, P Ag