Australia
April 11, 2012
A thorough assessment of risk associated with sowing canola this year is not just important – it is critical.
That is the clear message being directed to canola growers who face the prospect of losing crops if blackleg disease takes hold.
Grains Research and Development Corporation (GRDC) Southern Regional Panel chair David Shannon says the risk of blackleg infection in crops and potential for yield losses this year remains extreme.
Mr Shannon says it is therefore imperative that growers and their advisers implement management strategies before they begin sowing, to reduce the risk to crops and the broader industry.
“Blackleg can completely wipe out a crop so it is crucial that measures are taken now to minimise the potential for disease during the growing season.
“If blackleg becomes rampant, it will not only decimate this year’s crops but the long-term future of the canola industry could be threatened.”
The risk of blackleg infection in crops and potential for yield losses this year is severe due to the increased area sown to canola in 2011 and the prediction of another large planting in 2012. Because it survives on canola stubble, last year’s expansive crop has heightened the risk this season.
Central to any blackleg management strategy is the need to avoid sowing canola on canola.
“Separating this year’s canola crop from last year’s canola stubble is priority number one,” Mr Shannon said.
“Because blackleg fungal spores are released from canola stubble, the disease is more severe in areas of where canola is intensively grown each year.
“Fungal spores can be spread widely and extensively through wind and rain-splash which means any canola crops going in this year need to be separated from last year’s stubble. Being aware of neighbours’ cropping programs is also important.”
Some canola varieties are more susceptible to blackleg disease so investing time in selecting the most appropriate varieties to sow this year is also strongly encouraged.
To assist growers in their variety selection, the Canola Association of Australia, with support from the Grains Research and Development Corporation (GRDC) and state agriculture departments, has released blackleg resistance ratings for 2012.
Mr Shannon said the ratings were a vital resource to guide growers in choosing a blackleg-resistant cultivar. The 2012 blackleg resistance ratings are now available online at www.grdc.com.au/National-Blackleg-Ratings-2012.
“Growers are urged to assess the risk of sowing seed from varieties that are more susceptible to blackleg. Choosing the best variety for their particular situation is a must.
“If accessibility to seed of recommended varieties becomes an issue, growers should avoid sowing just any line of seed for the sake of putting in a crop.
“They must weigh up all the risk factors involved because at the end of the day it is not worth planting a crop in a situation where blackleg is more than likely to occur.
“There are implications not only in yield and financial losses in the short term, but the long-term impact on cropping systems for that grower and the wider industry could be devastating.”
The GRDC recommends 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 Risk Assessor, developed by the GRDC and industry partners, can help growers and advisers determine if a high risk situation exists in certain paddocks and which management practices can be changed to reduce the risk of severe blackleg infection.
“By changing particular management strategies, the risk of blackleg in a paddock can be minimised. For example, if the same cultivar of canola or juncea-canola has been grown for three years, switching to a different cultivar can reduce the risk of blackleg.”
Mr Shannon said that additional strategies for managing blackleg included using either a fungicide seed dressing or fungicide-amended fertiliser.
The blackleg fungus is adept at overcoming cultivar resistance and is becoming more prevalent in areas where it had previously not been detected.
“Staying on top of blackleg disease is the responsibility of everyone involved in the oilseed industry. We must all do what we can to reduce the risk and ensure that the industry remains viable well into the future,” Mr Shannon said.
Key points to reduce blackleg risk in 2012
- Avoid sowing this year’s canola crops into last year’s canola stubble
- Separate this year’s plantings from last year’s stubble
- Be aware of neighbours’ cropping programs
- Select the most appropriate blackleg-resistant varieties
- Blackleg resistance ratings for 2012 are now available online at www.grdc.com.au/National-Blackleg-Ratings-2012
- Consult the ‘Blackleg Risk Assessor’ fact sheet ( http://www.grdc.com.au/GRDC_Blackleg_FS.pdf ) for advice on all blackleg control practices
- Additional strategies for managing blackleg include using either a fungicide seed dressing or fungicide-amended fertiliser
- Weigh up all the risk factors involved in planting canola this year
Species
