Blackleg disease warning for lower EP canola growers
Growers of canola on South Australia’s lower Eyre Peninsula are being urged to take measures to prevent severe blackleg fungal disease in their crops this season.
The Grains Research and Development Corporation (GRDC), with the support of industry authorities, local agronomists and farming groups, is advising lower EP growers to be aware of the risks of sowing the canola cultivar Hyola®50 due to high levels of blackleg infection in this cultivar within the lower EP region in 2011.
A blackleg monitoring trial site at Wangary, managed by the Lower Eyre Agricultural Development Association (LEADA) and funded by the GRDC, last year recorded internal infection levels in Hyola®50 of 71%, compared with 16% in 2010.
Blackleg authority Steve Marcroft, of Marcroft Grains Pathology, says typically yield loss will occur in plants with more than 30% internal infection, with severe yield loss occurring in plants with more than 50% internal infection.
Dr Marcroft says because Hyola®50 has been grown extensively on the lower EP, an even higher level of disease severity could occur this year if the cultivar’s resistance is overcome by the blackleg fungus.
In other sites that were surveyed across South Australia, New South Wales, Western Australia and Victoria, the level of disease in Hyola®50 is still low (less than 25% internal infection).
Dr Marcroft, who is the national blackleg ratings coordinator, and the GRDC have developed a fact sheet specifically for lower EP canola growers to assist them with their canola programs in 2012. The GRDC fact sheet is accessible via www.grdc.com.au/blackleg2012.
In summary, the measures that should be taken include:
1/ Choose a canola cultivar with high levels of blackleg resistance for the Eyre Peninsula noting varieties with recent resistance changes (use only the current year’s ratings). Blackleg ratings are available via www.nvtonline.com.au.
2/ Separate this year’s canola crop from last year’s canola stubble by a minimum of 500 metres.
3/ Do not sow Hyola®50 within 500 metres of its own stubble from a 2011 or 2010 crop (older stubble does not release enough spores to warrant concern).
4/ Ensure that canola seed has been treated with fluquinconazole or fertiliser amended with flutriafol as an insurance against blackleg.
5/ Monitor blackleg severity within the 2012 crop to assist with decision making in 2013.
Dr Marcroft says other cultivars may also become susceptible to the Hyola®50 stubble on lower EP. The cultivars at risk are listed in the fact sheet.
Blackleg is the most severe disease of canola in Australia, causing yield loss and in some circumstances total crop failure.
“It is managed by breeding disease resistance into canola cultivars and by crop management practices,” Dr Marcroft said. However, the blackleg fungus is adept at overcoming cultivar resistance, leaving many crops vulnerable to significant yield loss.”
The GRDC and Dr Marcroft recommend that growers consult the ‘Blackleg Risk Assessor’ fact sheet (http://www.grdc.com.au/ GRDC_Blackleg_FS.pdf) for advice on all blackleg control practices.
The Blackleg Risk Assessor was developed by the GRDC and industry partners to help farmers make the right choices before sowing canola.
Dr Marcroft says growers can use the Risk Assessor to determine if their paddocks are in a high risk situation, and what practices could be changed to reduce yield loss from blackleg.
“It lists all the factors that will influence blackleg severity on a grower’s property,” he said.
Caption: Canola stalks (on the right) infected with blackleg. Photo Ray Colwey.
GRDC Project Code: MGP00003
Media releases and other media products can be found at www.grdc.com.au/media
For further information: Dr Steve Marcroft
Marcroft Grains Pathology
0409 978 941
Contact: Sharon Watt
GRDC Project Code