Objectives
- To demonstrate canola yield and quality response to a wide variety of seeding dates in various locations in SK.
- To demonstrate what seeding date is best for avoiding high flea beetle pressure in canola.
- To demonstrate if a higher canola seeding rate is a good management strategy for protecting yield in the event of heavy flea beetle pressure.
Project Description
The 2025 demonstration was carried out at four Saskatchewan Agri‑ARM sites—Melfort, Scott, Outlook, and Swift Current—to evaluate how canola seeding date and seeding rate influence emergence, flea beetle pressure, maturity, yield, and quality. The study used a split‑plot design in which seeding date served as the main plot factor and seeding rate as the subplot factor. Three seeding dates were implemented: an ultra‑early date in late April to early May, a typical date in mid‑May, and a late date in late May to early June. These dates were applied in strips and not randomized, with each subsequent date targeted 10–14 days after the previous one, depending on snowmelt and field conditions at each site. Seeding rates differed between dryland and irrigated locations: the 1X rate was 40 seeds/m² at Melfort, Scott, and Swift Current, and 100 seeds/m² at the irrigated Outlook site, with the 2X rate doubling the respective 1X rate. This created six treatment combinations; each replicated four times.
Crop management practices such as fertility, cultivar selection, crop protection, and row spacing followed best management practices at each site. Data collection included soil testing to determine fertility needs, monitoring of environmental conditions throughout the growing season, and measurement of soil temperature at seeding (recorded at 8 AM and 4 PM). Emergence was tracked by recording the number of days from seeding until approximately 75% of plants had emerged. Plant density was measured two weeks after emergence by counting plants in four one‑meter row sections and converting counts to plants per square meter. Flea beetle damage was assessed at the two‑leaf stage using the Canola Council’s defoliation guide, with 20 plants evaluated in two locations per plot. Maturity was recorded when plots reached 60% seed colour change, and days to maturity were calculated from the seeding date. Grain yield was determined by weighing harvested plots and converting the weights to kilograms per hectare, while oil content was measured using NIR analysis on cleaned grain subsamples. Each site’s data was analyzed independently using split‑plot ANOVA in Statistix 10.
Grower Benefits
In this demonstration, seeding canola early often decreased plant stands (75% of the time), increased flea beetle defoliation (75% of the time), and increased days to maturity (100% of the time), while results of yield and oil were inconsistent across locations. An increased seeding rate often increased stands (75% of the time), decreased days to maturity (50% of the time), and decreased (25% of the time) or increased (25% of the time) oil. Scott and Swift Current had ultra-early seed dates in late April, while Melfort and Outlook were in early May, but soil temperatures were always near or well above 5°C, suggesting soil temperatures were good for canola emergence regardless of seeding date. Days to emergence were longest when late April seeding, but when ultra-early seeding in early May, there was very little difference in days to emergence as compared to mid to late may seeding. Plant stands were often reduced with ultra-early and/or typical seeding as compared to late seeding at 75% of the sites. An increased seeding rate also increased stands at 75% of sites. Ultra-early seeding demonstrated significantly increased flea beetle defoliation at 75% of site, while at one location typical seeding also demonstrated greater flea beetle defoliation as compared to late seeding, which always demonstrated the least flea beetle pressure. Seeding early always increased days to maturity, while seeding at an increased rate decreased days to maturity at 50% of sites. At Melfort, there was a significant interaction of date and rate for maturity, where the typical seeding date had hastened maturity at a 2X seed rate, while the other dates did not demonstrate this difference. This was likely a result of different environmental conditions at crop maturation. The effects of ultra early seeding on canola yield led to similar yields to a typical seeding date at Scott, decreased yields at Swift Current, higher yields at Outlook, and no differences in yield at Melfort. Oil was only reduced with ultra early seeding at Swift Current, while at Outlook, oil was reduced for typical seeding as compared to late seeding, but both were comparable to ultra-early seeding. Lastly, an increased seeding rate increased oil at Melfort, but decreased oil at Swift Current. Based on the results of 2025, ultra early seeding has the potential to decrease canola stands, while increasing the risk of flea beetle pressure, while the effects on yield and oil tended to be very location dependent, suggesting that differing environmental factors had a large impact on yield and oil. Furthermore, seeding rate was effective at increasing stands and hastening maturity, while having very little effect on flea beetle pressure and yield, with an inconsistent effect on oil. There were very few instances of a significant interaction of seeding date and rate in 2025, suggesting that seeding rate had the same effect on canola regardless of seeding date.
Link to Year 1: Demonstrating benefits of seeding date and rate on canola yield and quality
Link to Year 2: Does seeding date and rate of canola effect spring flea beetle pressure, yield, and quality?
Fact Sheet: Fact Sheet- Canola seed dates and rates-2023-25
