All varieties recommended for sowing in Western Australia have good adult plant resistance to blackleg. However, there is still a need to maintain good management and hygiene practices to keep blackleg disease to a minimum, even when using blackleg resistant varieties. Leave canola out of the rotation for at least three years to allow diseased residues to decompose and reduce the risk of ascospore infection. In recent years, some growers have successfully reduced this break period, but there is increased risk from this practice. If there is no erosion risk, destroy crop residues after harvest to reduce carryover of the fungus on infected stems.
Graze stubbles heavily to reduce fungus carryover.
Plant canola as far as possible from previous canola crops to reduce the risk of infection by wind-borne ascospores. Avoid planting in areas downwind from old stubbles where the prevailing winds are likely to blow air-borne spores. White leaf spot White leaf spot disease can be found in most plantings, but is not usually a cause of heavy yield losses. Symptoms Symptoms include greyish-white to brown leaf, stem and pod lesions . Lesions often have a brown margin.