What is the best canola seed choice for each field? Answering this question will take some thought and could be a key step to higher productivity and profitability. The best canola seed choice, or choices, may not always be the farm’s highest-yielding cultivar from the previous growing season.
The decision tree below can help farmers and their agronomists think through the decision process.
Decision tree, step by step
Step 1. List your “must have” traits
Write down the traits essential to your system. These could be herbicide tolerance, days to maturity, pod shatter tolerance, specialty oils, disease resistance and others. The section below describes each option.
Step 2. Calculate which cultivars produced your most profitable canola fields this year
Cultivar choice can be a key part of field profitability. Look at yield, quality, seed prices, in-season input requirements, harvestability, fertilizer use efficiency and any other factors that influence profitability and the overall growing experience. Examine the cultivars you grew. Can you pin higher profitability on any specific features related to seed or seed treatment? Change your “must have” list accordingly.
Step 3. Look beyond the current year and beyond the farm gate
Investigate cultivars that provide consistent, year over year, performance in your area. Some cultivars yield consistently at or near the top in any conditions. Review results over the past few years on your farm. Ask neighbours and local seed suppliers for their thoughts. Check seed company trial results. Honestly evaluate the whole range of available cultivars and what beneficial traits and performance they bring to the table. Change your “must have” list accordingly.
Step 4. Critically examine your “must have” list
Try to envision a better way to grow canola. Think about what other farmers are doing, what local research organizations have shown, what end users are buying, and for what price. Honestly evaluate your system. If the approach is sound, carry on. If you might like to try something new, at least for one cultivar, change your “must have” list accordingly.
Step 5. Note the top yield robbers on the farm
If certain pests, such as blackleg, clubroot and flea beetles, consistently reduce canola yield on the farm, look at new sources of resistance and seed treatments to manage those pests. If drought or heat were big yield robbers, ask seed companies if they have cultivars that seem to perform better under these environmental stresses. Change your “must have” list accordingly.
Step 6. Develop a short list
Use your refined list of “must have” features to create a short list of cultivars. Choose at least two to grow next year based on yield potential, yield stability and overall profit potential.
Common canola traits
- Clubroot resistance. As clubroot populations become more diverse in fields, and as seed companies release new resistance genes, farms may see a benefit in rotating resistance sources. When clubroot causes yield loss in resistant cultivars, ask seed companies about cultivars with a different source of resistance. Clubroot risk maps. See the table here for a list of cultivars with clubroot resistance.
- Blackleg resistance. In fields with yield-robbing levels of blackleg, use cultivars with a blackleg resistance group (RG) that works against the common blackleg races in that field. A stubble test will identify the dominant blackleg races in a field and provide tips for RG selection. Visit blackleg.ca and go to “Identifying blackleg” to find labs that test stubble for blackleg races. See the table here for a list of cultivars with blackleg R genes.
- Other disease resistance. Some cultivars may have higher verticillium tolerance than others, but no verticillium stripe resistance rating system exists for canola. Some cultivars may also have higher levels of sclerotinia stem rot tolerance. Ask seed companies. Cultivars with tolerance to sclerotinia stem rot will provide some peace of mind in those situations where the decision to spray is not so easy.
Pod shatter resistance
The official canola shatter ratings of 1-9 represent a cultivar’s pod shatter risk relative to designated checks. The higher the number, the greater the pod shatter resistance. See CanolaHarvestManagement.ca for more information on canola shatter ratings, pod drop and various canola harvest management topics. See the table here for pod shatter ratings for participating cultivars. Cultivars with pod shatter tolerance are better suited to late swathing and straight combining, which can improve yield and provide more flexibility on harvest timing.
Days to maturity
Cultivars with shorter days to maturity could be more profitable on fields often seeded late because of drainage issues, in the Brown soil zone where intense summer heat can reduce yields, and as a strategy to spread out harvest. Canola Performance Trials data site has days to maturity comparisons for cultivars grown up to 2022.
Herbicide tolerance system
What herbicide tolerance (HT) system best controls the major weeds in each field and best meets the whole-rotation needs of the farm? Cultivars stacked with both glyphosate and glufosinate tolerance can be particularly effective on wild oats. Many wild oat populations are resistant to multiple groups, so the stack provides a rare opportunity to hit wild oats in-crop with two effective herbicide groups. Farmers who list glyphosate tolerance as a must-have trait and who also have glyphosate-resistant kochia may consider a cultivar with stacked HT systems. Marketing can also enter the HT decision, with Clearfield cultivars suitable for non-GMO markets. The Canola Encyclopedia describes each HT canola system.
Cultivars with specialty oils provide a different marketing opportunity along with premiums, specified delivery dates and on-farm pick up.
- Seed treatment. Getting the greatest value from seed treatment will require some thought about field histories for insects and disease. For example, Buteo Start provides advanced flea beetle protection while Lumiderm (and solo cyantraniliprole products) are better for cutworms. Which is best? Do you need both? Also, if a cultivar does not have a blackleg R-gene and blackleg is a potential yield risk, consider Saltro seed treatment.
- Lodging score. If you want to increase nitrogen rates, note that some cultivars may be more prone to lodging. Consider cultivars with high lodging resistance.
- Weather resilience. Some cultivars may perform better or worse in certain environmental conditions. Because we can’t predict growing season weather, planting a few different cultivars may hedge the bet somewhat. Seed companies may have insight into which cultivars perform best in low moisture, high moisture, high heat and other weather scenarios you often encounter.
Bottom line: Grow more than one cultivar
Growers often want to experiment with at least one new cultivar each year. Rather than put that cultivar in its own field, consider seeding a block through the middle of a field of the farm’s current favourite cultivar. That way the two cultivars get a head to head test in the same field with the same soil type, weather and field history.
If a farm grows only one canola cultivar and has an issue with performance, they may not be able to determine whether a different set of genetics might have helped in their scenario. With two or more cultivars, performance can be compared and analyzed. Through this process, farms can start to do their own “phenotyping” – which is to analyze genetic performance based on local growing conditions.