Strategies to manage blackleg in canola fields effectively
Blackleg is a serious disease affecting canola crops, leading to reduced yield, quality issues, and market risks.
To minimize its impact, growers can follow an integrated blackleg management strategy, starting with smart seed selection and additional practices to keep the disease in check.
Integrated Blackleg Management Strategy
Managing blackleg starts with breaking the disease cycle, as the pathogen survives on infected residue left in the field.
Growers should maintain at least a two-year gap between canola crops to give residue time to decompose, reducing disease risks for the next crop.
Planting canola varieties with blackleg resistance is crucial. Select seeds rated "R" (resistant) and rotate varieties to introduce different blackleg resistance genes, which help slow down the disease's spread.
Testing for blackleg races in the field can also guide seed choice, helping match specific resistance genes to the prevalent races.
Regular field scouting is essential in any blackleg management plan. Checking plants for symptoms and disease incidence helps growers assess how effective their current practices are.
Pre-harvest scouting, especially around 60% seed colour change, is an ideal time to spot blackleg symptoms. Growers can pull up plants in a W-pattern across the field, then inspect the base of the stem for blackened tissue.
Disease severity is rated on a scale from 0 to 5, where each increase in severity indicates a potential yield reduction.
Fungicide and Weed Management
Fungicide treatments can be beneficial, particularly in high-risk areas. Seed treatments can protect young plants from early infection, and applying a foliar fungicide early in the season helps in maintaining yield.
During non-canola years, it’s essential to control volunteer canola and Brassica weeds such as stinkweed and wild mustard, as they can harbour blacklegs and contribute to its spread.
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