Growers of canola are being advised to manage blackleg risk in this year’s crop by adopting a strategic sowing program.
To minimise the risk of blackleg, growers are urged to separate this year’s canola crop from last year’s canola stubble by a distance of at least 500 metres.
According to Trent Potter, senior research scientist at the South Australian Research and Development Institute (SARDI), it is also recommend that growers avoid planting a crop of canola within 500 metres of stubble of the same variety sown up to two seasons prior.
"Fungal spores from a stubble are more likely to infect the same variety more severely the following season," Mr Potter said.
"Growing the same canola cultivar for the third year or more enhances the risk of blackleg infection."
And while the risk of blackleg is greater in higher rainfall areas (those with a growing season rainfall of more than 330 millimetres), Mr Potter encourages all growers to take steps to reduce the incidence of fungal blackleg.
To assist growers with blackleg management, a fact sheet has been developed based on surveys, trials and research funded by the Grains Research and Development Corporation (GRDC) and the Australian Oilseeds Federation (AOF).
Surveys and data for the fact sheet were provided by the Lower Eyre Agricultural Development Association farming system group, MacKillop Farm Management Group, SARDI and Marcroft Grains Pathology.
In addition to sowing recommendations, the fact sheet provides variety advice.
Growers are advised to choose a canola variety with good blackleg resistance and to ensure that canola seed is treated with a fungicide as an insurance agent against blackleg.
Growers should also monitor for blackleg within the 2009 crop.
Mr Potter said canola remained an important component in southern cropping rotations.
Its value in weed management and as a cereal disease break crop continues to be recognised, and wheat yields are on average 20pc higher after canola than after wheat.
Timing of sowing would again be a critical factor for growers this season, according to Mr Potter: "If they can get the crop in early enough, they have the potential to make good money from canola.
"However, that potential is reduced with any delay in sowing.
"Yield is likely to drop 5pc per week in South Australia and Victoria, and 10pc per week in southern and central NSW.
"Oil content will fall 0.5 to 0.8 percentage points per week with delayed sowing."
Mr Potter said the optimum time for sowing canola differed from one region to another.
For example, growers in low rainfall areas, such as the Mallee, have a narrower window for sowing, one which generally closes after the third week of May.
In the low rainfall areas of southern and central NSW, it closes even earlier, after the first week of May.
In higher rainfall areas, such as the South-East of SA, reasonable yields can be achieved from crops sown as late as early July.
Growers wanting to know more about how they can reduce the incidence of blackleg this season can click here to obtain the fact sheet, Managing Your Risk of Blackleg in Canola.
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