Spring and Winter Canola: Harvest and Storage

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Pub 811: Agronomy Guide > Spring and Winter Canola > Harvest and Storage

Excerpt from Agronomy Guide for Field Crops
Order OMAFRA Publication 811: Agronomy Guide for Field Crops

• Introduction
• Direct Harvest
• Swathing
• Pre-Harvest Herbicides to Assist Canola Harvest
• Combining Canola

Introduction

Direct combining is the most common method of harvest, although swathing is used in some areas. Direct combining usually results in improved seed quality compared to swathing, due to fewer fines and less green seed. For more information on harvesting, see the Canola Council of Canada "Harvest Management" section of the Canola Growers Manual publication (www.canola-council.org).

Direct Harvest

Direct combining is most successful when the crop ripens evenly, is relatively free of Alternaria disease, is heavy, partially lodged and well knitted together. These conditions reduce the risk of shelling and pod drop due to wind. For direct-harvested canola, the crop is ripe when the pods rattle if shaken. Some varieties are less prone to shattering and are well suited to direct combining. If the crop maturity is uneven, the need for, and cost of, using a desiccant should be evaluated versus swathing the crop. Seed oil content tends to be higher when a crop is direct harvested. Harvesting in the direction of the lean will significantly reduce shatter losses.

Swathing

The optimum stage to swath canola is when 50%-60% of seeds on the main stem have changed colour. Farms with large areas of canola should start swathing at 30% colour change to ensure that the majority of acres can be swathed at near-optimum maturity without the risk of over-ripening and shelling. Canola ripens and dries quickly in the swath. Usually 5-10 good drying days will lower the moisture so that seeds in the upper pods are firm. Canola seed can drop by 1% moisture or more per hour in the swath.

Seed colour change is a better indicator of maturity than pod colour or overall colour of field. In staging maturity, examine only those pods on the main stem. When 30%- 40% of seed has started to change colour from green to yellow-brown, overall moisture content will be 30%. The pods at the bottom of a canola plant ripen first, therefore the pods at top may still be greenish when the field is ready for swathing. Do not let premature ripening caused by Sclerotinia or Alternaria, influence optimum stage to swath. Most of the crop yield will come from healthy plants. Pick a point at which the majority of the field is at correct stage, ensuring that in less mature areas that seeds are green, firm and no longer translucent. It often helps to swath when the crop is moist with dew or during a light drizzle. The stubble should be left tall enough, about 25-30 cm (10-12 in.) to support the swath (and minimize combine wear). To learn more about proper field assessment, see the Canola Council publication Canola Time of Swathing Guide or visit the website at www.canola-council.org/pub_swathing.html.

Pre-Harvest Herbicides to Assist Canola Harvest

A pre-harvest herbicide application can facilitate direct harvest by speeding up dry-down of canola plants and weeds to allow for timely harvest and reduce dockage from green seeds. Application can be helpful if the crop is uneven, reducing the risk of shattering in mature plants while waiting for immature areas to dry down. Application will speed up dry-down, but not plant maturity. Harvest the field as soon as the crop is ready, as further dry-down increases risk of shattering loss. If winter wheat is planned and perennial weed pressure is high, a pre-harvest burn-down may be the best option for weed control, since there isn't enough weed top growth for effective control after harvest. Glyphosate applied to Roundup-Ready canola will assist with dry-down of weeds and control of perennial weeds, but it will not help to dry down the crop.

Combining Canola

The optimum time to harvest canola is when there are few green seeds and seed moisture content is less than 10%. Do not delay harvest as seed loss due to shatter increases dramatically approximately 10 days after optimum harvest timing. Depending on weather conditions, seeds rapidly lose moisture at 1%-3% or more per day. Shattering losses can be reduced by combining at higher seed moisture content and drying the crop, harvesting when there is a dew or harvesting at night. Many operators start combining when the seed is slightly above 10% moisture. Check green seed content, to harvest a quality sample. Based on crushed seed examination, No. 1 and No. 2 Canada canola grades may contain a maximum of 2.0% and 6.0% distinctly green seeds, respectively.

Hot or windy weather can result in seed at a moisture content that indicates it is ready for combining, before there has been sufficient time to clear itself of green chlorophyll. Several dews or a light rain can help seed to clear the green colour. Monitor and make adjustments throughout the day to minimize harvest losses. Average harvest losses range from 10-50 kg/ha (9-45 lb/acre). A loss of 1 kg/ha equates to about 54 seeds/m² (5 seeds/ft²) on the ground.

For further information on drying, handling, and storage of canola, see Storage of Canola on the Alberta Agriculture website at www1.agric.gov.ab.ca/.

Figure 6-1. Canola Scouting Calendar