Late-Harvested Crops Require Careful Attention

With several crops still in the field, farmers must decide what to harvest first, at what moisture content and how to store for long-term quality.

Sunflowers can hold out longer than swathed canola if the sunflowers are disease free and in good shape. And flax is less likely to shell out than canola. Some crops, especially sunflowers, will likely need to dried.


If all crops are ready combine the canola first. Even in a swathed field, seeds shell out. The Canola Council of Canada (CCC) recommends harvesting canola before winter. Moulds and a buildup of free fatty acids in the oil can drop a No. 1 or 2 to Sample grade by spring.

Canola can be sold at 10 per cent moisture, but almost no elevator will take seed above 10 per cent moisture. Canola can be combined at higher moisture levels and the moisture reduced. The moisture content will determine the drying system. Aeration might not be enough this time of year.

Canola will go through a “sweating stage” for six weeks after harvest, where moisture and temperatures can rise in spots in a bin. Careful monitoring is required. See CCC information on canola storage at:


Aeration fans should run as the seed is unloaded. A large perforated floor is required due to the difficulty of moving air through small seeds. Don’t overfill the bin. Temperature and moisture should be monitored to determine if the moisture is coming down.

With aeration, canola in the bottom of the bin will be drier than canola higher in the bin. Take samples from throughout the bin. Be ready to manually mix the canola to ensure uniform drying.

With cool, moist days, natural air may not be enough to lower the moisture content to less than nine per cent for safety. If the moisture isn’t coming down, consider using a heated batch or continuous air dryer.


When high-moisture canola is being combined it must be dried for safe storage. Once the moisture is down, then canola can be stored in an aeration bin to continue to condition it. Overheating can cause seed to heat, reducing quality or start a fire.


Cold temperatures may be required in areas where the moisture content is high and the ground is wet, essentially freeze drying the seed. This works as long as the seed can go through the sieves and into the hopper. The challenge is keeping the sieves clear of ice.


Flax can take a little more weathering than the canola. This year farmers are finding the seed is usually dry (less than 10 per cent moisture), but the stalks are green and wrap on the reel. Swathing will cut the stem, allowing it to dry.

As well, swathed flax will be easier to pick up with a combine header later this fall or next spring. The longer flax is in the field exposed to freeze-thaw cycles, the poorer the quality.

Discoloured flax overwintered in the field is not likely suitable for the human consumption market.


Under the right conditions aeration can work, but it could take more. Tough flax is 10.1 to 13.5 per cent moisture; damp flax is over 13.5 per cent moisture. Flax is also prone to heating and requires attention for at least six weeks after harvest.

Once flax starts heating, it will spread quickly.


For long-term storage sunflowers should be nine to 10 per cent moisture. But harvesting sunflowers at higher moisture can result in higher yields due to less bird feeding, seed drop and disease. This year, drying is probably mandatory.

Sunflowers can be damaged during harvest if the moisture content exceeds 16 per cent. Friction that removes the seeds from the head also can cause highmoisture seed coats to peel off a fine layer of the black shell. The seed coat looks white and resembles damage caused by sclerotinia head rot. The nutmeat inside is sound, but the visual appearance results in downgrading.

Drying with bin, batch and continuous-flow dryers works. Check the guidelines for drying sunflowers in the user’s manual. High drying temperatures may cause the nutmeats in confectionery sunflowers to be steamed, wrinkled or even scorched, which lowers the grade and price. Fire is a hazard when drying sunflowers. Keep equipment clean and do not leave unattended while running.

About the author

Manitoba Agriculture

Anastasia Kubinec is manager of crop industry development for Manitoba Agriculture.



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