1. Review the appropriate target plant stand
The recommended target stand of five to eight plants per square foot is based on meta-analysis of canola hybrid studies from Western Canada. University of Saskatchewan professor and researcher Steve Shirtliffe conducted the meta-analysis, and concluded that it is more profitable to target the lower end of the range when seed costs are high and the crop selling price and crop yield are low. But don’t go too low. Yield potential drops with plant populations lower than five per square foot, and thin stands increase the risk from flea beetles and weed competition. More on that below.
2. Achieve uniform seed emergence
Uniformity in terms of plant population across the field and crop staging is an important start for a competitive, high-yielding crop. Consistent seed placement into the top half-inch to inch of topsoil greatly improves seed survival, as does somewhat warmer soils. These steps to increase seed survival and improve the return on investment may require a well-maintained seed tool and perhaps slowing seeding speed, which take time but not excessive out-of-pocket cost.
Uniform, rapid emergence also improves crop competition against weeds and flea beetles. Fungicide and harvest timing improve with all plants at equal maturity.
3. Choose seed with disease resistance to match threats
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 identified. Consider an improved blackleg seed treatment with tight rotations and limited information on blackleg races in a field. Cultivars with clubroot resistance and increased sclerotinia stem rot tolerance can also reduce yield loss with relatively little additional cost. Growers could also ask seed companies about cultivar differences in verticillium stripe performance.
4. Cost-effective approaches to flea beetle management
If farms pencil in one or more flea beetle sprays, starting off with more plants per square foot and an improved seed treatment may offset the need to spray. The question is which practice provides the most economical balance – more seed, better seed treatment or extra foliar sprays?
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