Winter Canola Survival in 2018/2019 in Southwestern Ontario

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 (Figure 1) 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.