CropAlert Blackspot and Sclerotinia July 2016

CropAlert Blackspot and Sclerotinia July 2016


Early, severe blackleg lesions have been detected across canola growing regions. Growers should monitor their crops for lesions to make decisions regarding fungicide application to limit yield loss.

Key considerations for management:

What is the yield potential of the crop? Higher yielding crops will have a greater economic return for fungicide application.

What is the black leg rating of the infected cultivar? With a rating of MR or less you should consider spraying a fungicide to prevent yield loss due to crown cankers.

Are you seeing high levels of disease? (are you seeing black leg lesions?)


Apply fungicide at the 4-6 leaf stage. Applying fungicides still has some efficacy at the 8 leaf stage for high yield potential crops.

For more detailed information see:

Early severe blackleg infection requires fungicide application article from eXtensionAus

Blackleg – Canola chapter – Crop Disease Manual


Recent weather conditions in south-eastern Australia have been conducive for the development of the disease. Sclerotinia stem rot has already been observed on very early sown canola on the Eyre Peninsula. Growers need consider the risk to their crop and look at  anagement now to prevent yield loss later in the season.

Key considerations for management:
  • Has sclerotinia been an issue in your district in previous years?*
  • How tight is your canola rotation? A tighter rotation enables fruiting structures to increase in frequency
  • Good winter rainfall to produce the inoculum.
  • Wet weather during flowing. This enables inoculum to infect the stems and cause stem rot.
  • Research from NSW DPI found temperature to be a minor driver of disease and that canopy wetness is key.
  • *In 2016 there are reports of sclerotinia appearing in growing regions that have not previously had
    serious sclerotinia issues.

Protect the main stem by applying fungicides as the 20-30% bloom stage (15-20 flowers open off the main stem).

  • For more detailed information see:
  • Wet conditions favour development of sclerotinia stem rot in canola article from eXtensionAus
  • Sclerotinia – Canola chapter – Crop Disease Manual
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