In Australia, canola can be infected by a number of pathogens ranging from root rots to leaf disease, crown rots and stem infections, (Table 11.1). As with all diseases their incidence and severity is dependent on plant susceptibility, presence of the pathogen and favourable climatic conditions. Generally, fungal disease such as blackleg and sclerotinia are more damaging in higher rainfall regions. However, if unseasonably high rainfall occurs in lower rainfall regions these areas may also experience high disease levels.

Disease control varies for each pathogen though, generally, variety resistance, crop production practices and fungicides are used either in isolation or combination to reduce economic losses. If growers are aware of the disease risks in their area and follow strategic management plans they should be able to adequately control most canola diseases.

Table 11.1 Common canola disease diagnostic key


Growth Stage

Plant Part Infected Possible Disease
Seedling Roots Damping off
  Hypocotyl Blackleg
  Leaves Blackleg, white leaf spot, downy mildew
Rosette Roots Damping off, blackleg, clubroot
  Crown Blackleg
  Leaves Blackleg, white leaf spot, downy mildew white rust
Flowering Roots Blackleg, clubroot
  Crown Blackleg
  Leaves Blackleg, alternaria, white leaf spot, white rust
  Stem & Branches Alternaria, blackleg
Podding Roots Blackleg, clubroot
  Crown Blackleg
  Stem & Branches Alternaria, blackleg, sclerotinia
  Pods Alternaria, blackleg, white rust