Western Australian canola growers are advised to take note of risk factors for sclerotinia stem rot and to apply fungicide - within the recommended spray window - if conditions are favourable for infection.
Canola stems infected by sclerotinia showing formation of bleached stem lesions. Photo by Steve Marcroft.
Department of Agriculture and Food (DAFWA) researcher Ravjit Khangura said the recent discovery of sclerotinia apothecia (fungal fruiting bodies) in canola paddocks in the Northampton, Geraldton and Moora areas indicated that sclerotinia could infect canola crops relatively early this year.
“Seasonal conditions so far, especially in the northern grainbelt, have been conducive to the early production of sclerotinia spores,” she said.
“However, the severity of sclerotinia in WA will also depend on coming conditions, with prolonged wet conditions and high humidity in the crop canopy favouring its development.”
Dr Khangura said the latest DAFWA research, supported by the Grains Research and Development Corporation (GRDC), showed that fungicides when applied to canola crops at the 15 to 30 per cent flowering stage were usually most effective in reducing yield losses caused by sclerotinia.
“Some early sown canola crops in the northern grainbelt are already at this stage of development,” she said.
Dr Khangura said the research also showed that all registered fungicides are effective and that if sclerotinia is controlled increases in crop yield can be achieved where there is high disease pressure.
“I encourage canola growers to assess their risk and have foliar fungicides on-hand and ready to apply at the optimum flowering stage, as the ideal spraying window can be as short as a few days,” she said.
“The crops with the highest risk are those that are sown in paddocks with a history of sclerotinia over the past three years.
“Last year, the disease severely damaged canola crops across high and medium rainfall zones of WA, causing an estimated loss of more than $59 million to the State’s canola industry.”
Dr Khangura said that while fungicides reduced crop damage from sclerotinia, the main management strategy was to reduce the frequency of host species – in particular broad-leaved crops such as canola, lupins, chickpeas and lentils.
With support from the GRDC, DAFWA is continuing research to refine the use of fungicides to control sclerotinia, and is developing a forecasting system for the disease.
More information on sclerotinia management is available from the following resources:
Ravjit Khangura, DAFWA
08 9368 3374
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827
GRDC Project Code
DAW00210, DAW00229, UM00051