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In the 2018/2019 winter canola season, 17 fields were monitored to evaluate winter survival of winter canola, and to support expansion of regions that can access crop insurance for winter kill. Information was collected from producers on soil type, planting date, planting equipment, fall fertility, canola hybrid, and growth stage prior to a hard fall frost to contribute to assessments of on-farm practices that support improved survival. The producers also provided harvest information including desiccation product used and date of application, harvest date, and final yield.
In autumn of 2018 plant populations were assessed in each field. Plants were counted at 12 random locations within each field using the hula hoop method for those planted on 7.5” rows. For those planted on 15” rows, plants were counted in two neighbouring rows along a 17’5” length. GPS coordinates of the 12 locations were recorded and stakes were left in the ground to mark the locations so that winter survival could be assessed in the spring. The initial populations were collected in mid-October.
Spring population counts were conducted in April or May. Plant counts were not collected if it was impossible to find the exact location where the autumn assessment was made because the stakes had heaved out of the ground or washed away. This was more common on fields with heavier soils. To generally assess the health of the canola plants in spring, some plants were cut at the soil surface to check for damaged vascular tissue.
Winter survival of winter canola is dependent on many factors including plant growth stage prior to a hard frost, drainage and soil type. Canola should have at least 4 leaves prior to frost but should not reach reproductive growth stages (bud formation or bolting). Growth stage prior to winter is influenced by planting date, seed bed preparation and planting equipment choice. The small seeds require a fine seedbed and minimal residue on the soil surface to reduce risk of slug damage. A seed drill can be used for planting but note that emergence will likely be variable, with plants at different growth stages prior to winter. A row unit planter can also be used to plant canola on 15” rows and typically results in higher rates of emergence (lower seeding rates can be used) and more uniform stands. Broadcast seeding or planting on rows wider than 15” is not recommended.
The target population for winter canola should be 5to 8 plants/ft2 or approximately 250,000 plants/ac. However, canola has a strong ability to branch and fill in at low populations. An even stand of healthy plants at 2 or 3 plants/ft2 in the spring can achieve yields similar to stands of 5 to 8 plants/ft2.
It is undesirable to have seedlings too close together because they compete with each other, resulting in long hypocotyls where plant crowns (growing point) are not set snug to the soil surface. This increases risk of poor survival because growing points are more exposed. For this reason, it can be beneficial to seed winter canola at a lower seeding rate than typically used for spring planted canola.
Planting dates for Kent and Essex county fields were appropriate for the region, although a high amount of rainfall in September negatively impacted rate of emergence and speed of plant growth in some fields. In fields that were most affected by September rainfall the canola did not reach the 4- to 6-leaf growth stage before winter, or only had acceptable growth and survival over the tile runs. Broadcast seeding at a very late date (Sept 30) also resulted in plants that were too small for winter survival.
Winter survival may have been improved in Grey and North Wellington counties if planting had been earlier in 2018. Emergence and fall growth in these fields was variable, so smaller plants died while larger plants survived. Unsatisfactory performance of a grain drill on a hilly field and extremely prolonged wet conditions in the spring of 2019 contributed to stand loss issues on these fields. The North Wellington field was extremely delayed and patchy but produced a very strong yield.
For entire article please visit website – www.fieldcropnews.com/2020/03/winter-canola-survival-in-2019-2020-in-southwestern-ontario/
Written by Meghan Moran, Canola and Edible Bean Specialist, OMAFRA and published on March 5, 2020.