Ontario winter canola seed sales expected to reach all-time high

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September 4, 2020

Winter canola seed sales have been very strong and Ontario acres in 2020 are expected to be higher than ever before. While research on the crop has been limited, some recommendations are outlined below based on experience over the past few years and experience with spring canola in Ontario.

Field Selection – Fields should have good drainage and low clay content. Seeds may fail to emerge with wet conditions after planting, and plants will rot in wet areas in the winter and spring. Heavier soils can also cause heaving which will kill plants or significantly reduce yield potential. Lower yields were often observed on clay soils in 2018/2019 even when winter survival was adequate.

Winter wheat is generally better at overwintering than winter canola. If winter wheat survival is poor on a given field, canola survival will likely be worse. Some producers have had success with canola on fields that tend to dry out in summer. The relatively dry conditions in spring and summer of 2020 were a factor in high yields this season.

Herbicide History – When selecting a field, look back at least 2 years in the field herbicide records. There are a number of restrictions and not all are listed here.

Infinity has a 10 month re-cropping interval to canola. Other products that have a 22 month re-cropping interval or more include imazethapyr (Pursuit, Optill), metribuzin (Sencor) and atrazine (Primextra, Marksman, etc.).

Herbicide application options prior to planting of winter canola are somewhat limited. The primary choices are glyphosate, glufosinate (Liberty), clopyralid (Lontrel) and trifluralin (e.g. Treflan) as well as grass control products. Eragon and 2,4-D can cause crop injury and should be avoided in pre-plant burn downs.

Consult the OMAFRA Guide to Weed Control – Publication 75 (Chapter 4, Table 4-4) for more information. Conventional winter and spring canola (i.e. those without herbicide tolerance traits, such as Mercedes) are the same species and have the same reactivity to herbicides, but not all herbicide labels have information on canola, or on winter canola planting time frames.

Planting Date – Planting date trials have been conducted in Essex County by Dr. Eric Page, AAFC Harrow. The most success was realized with planting in the first two weeks of September. Winter kill and yield losses increase beyond the 3rd week of September, but in a mild or longer fall season the losses with late planting were less extreme. Planting in August in southern counties would likely result in bolting in the fall (moving into reproductive growth stages and stem elongation); bolted plants typically do not survive winter.

Based on observations from Dr. Page’s trials, about 600 growing degree days (GDD, base 0°C) are required for adequate growth of canola in the fall. For reference, winter wheat requires about 450 GDD in the fall. The general recommendation is to plant winter canola 7 to 10 days before the ideal winter wheat planting date for your region (see the winter wheat planting date map). Canola survives through winter on its roots, where winter wheat survives on the seed.

For many, this means planting in the first two weeks of September. Late August planting may be appropriate for some areas such as Simcoe County, north Bruce and north Grey Counties. We hope to have more information about Eastern Ontario planting dates in the next 2 years based on trials at University of Guelph – Winchester Research Station. Winter canola is not recommended in Northern Ontario due to poor winter survival.

Before winter, plants would ideally have a tap root approaching the width of a pencil and 4 to 8 true leaves.

Learning Together – If you have any questions, contact me – Meghan Moran: 519-546-1725,

I am very interested in checking fields prior to winter and again in the early spring to monitor winter survival and learn more about management practices that are working on farms. In the new year I will post more information about assessing winter survival, spring fertilizer application, monitoring for cabbage seedpod weevil, and protecting the crop from white mould.

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– Written by Meghan Moran, canola and edible bean specialist, OMAFRA