Canola sclerotinia update

  • Northam
  • Irishtown
  • Wickepin

Plant pathologist Jean Galloway (DPIRD) has confirmed apothecia production at her research sclerote depots at Northam and Irishtown (in mid-July) and at Wickepin last week.

Plant pathologist Ravjit Khangura (DPIRD) says recent rain events coupled with high humidity in many canola growing districts have elevated the risk of sclerotinia spore production and petal infection. Therefore canola crops in high risk paddocks that have just commenced flowering or are at early bloom stages will need protection.

Growers are urged to look at the current weather conditions and the forecast for the next week or so before deciding on applying a fungicide spray. The spraying window is between 20-50% bloom.

DPIRD research over the past few years has shown that generally a well-timed single spray can effectively control the disease and provides the best return on investment. However, when there are extended seasonal conditions two sprays may be required to get the maximum responses to fungicide applications.

Sclerotinia lesions on a canola leaf
Two small sclerotinia lesions and a large lesion on a canola leaf. Photo courtesy of Ravjit Khangura (DPIRD)

Whilst fungicides need to be applied before the disease symptoms appear on the main stem, symptoms on the leaves can be used as an indicator that disease will appear on the stems provided conditions stay wet and humid over the next couple of weeks.

Further information can be found at the department’s Managing sclerotinia stem rot in canola page and Ravjit’s 2017 Research Updates paper Sclerotinia in canola – ground infections, effect of row spacing, plant density and fungicide. Is it worth spraying after you see the disease?.

For more information contact Ravjit Khangura, Research Officer, South Perth on +61 (0)8 9368 3374.