There is a mild and an aggressive strain. The aggressive strain is now widespread. Scouting Techniques Control Tips Host Crops Canola and rapeseed.
Wild mustard is also an important host.
Biology Blackleg overwinters on infected canola stubble and can survive for at least 2 years. The blackleg fungus may also occur at low levels in the seed. However, this amount can introduce the fungus into new areas. The fungus is spread by rain-splashed spores, windborne spores, and by infected seed. Leaf spots can occur from the seedling stage to maturity.