Seed decisions based on the opportunities and challenges in each particular field can improve productivity and profitability of canola. Here are some scenarios describing how a farm might benefit from adopting this strategy:
To try clubroot-resistant genetics. This is a good strategy for most of the Prairies now that clubroot is fairly widespread. Farms in orange or red parts of these maps should definitely grow clubroot-resistant canola. Fields that have used clubroot resistance at least twice may be good candidates for a new source of resistance. The Canola Encyclopedia has a list of CR canola cultivars.
To take some pressure off the sclerotinia spray decision. 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.
To address an increase in blackleg disease in a field. In that situation, growers will be able to choose a cultivar with a different major gene for blackleg resistance. A stubble test to identify the most common blackleg race in a field will allow rotation of major gene resistant germplasm using information available from many of the seed suppliers. Change up the quantitative resistance deployed in the field if using cultivars where major genes are not identified. Read the Management section here.
To provide some harvest choices. Cultivars with improved straight cut features or pod shatter tolerance are better suited to late swathing and straight combining, which could provide a little more flexibility on harvest timing and method.
To spread out harvest. Unless there are major delays with spring seeding, a good strategy to ensure an actual difference in maturity at harvest is to seed the earlier-maturing cultivars before seeding other cultivars. Otherwise, if those earlier-maturity cultivars are seeded much later than later-maturing cultivars, a useful difference in harvest time is unlikely.
To hedge bets on weather. 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. Check Canola Performance Trials and look at cultivars that show more consistent results year to year and site to site. Seed companies want to start identifying cultivars that are best suited to certain situations, such as soil zone, moisture or cool springs. They’re not there yet, but they might have some rough ideas on cultivars that seem to perform differently in different situations, so you might ask for their advice. Canola Watch article on multi-year comparisons.
To rotate weed management. Herbicide rotation is always good practice, but knowing your weeds can drive more specific strategies when it comes to canola cultivar choice. For example, the Roundup Ready system is better for Group-1-resistant wild oats, and the Liberty Link system is the better choice if the field has known or suspected Group-9-resistant kochia. Also keep in mind that other glyphosate-resistant weeds like Canada fleabane could be moving in from the U.S. as well. The Canola Encyclopedia describes each HT canola system.
To choose cultivars that may respond better to higher fertility rates. Some cultivars may be more prone to lodging with increasing N rates. Check Canola Performance Trials for lodging scores.
To expand marketing opportunities. A few fields seeded to a specialty canola cultivar could cover off many of the points above while also providing a different marketing angle with premiums, specified delivery dates, on-farm pick up or whatever features the contract provides.
Bottom line: 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.