The most recent Blackleg ratings for canola have been released by the Grains Research and Development Corporation (GRDC) in the GRDC Blackleg Management Guide autumn 2018 edition.
The Leptosphaeria maculans fungus causes Blackleg disease, which in the past has had a significant impact on canola production.
The guide gives growers an understanding of what the disease rating is for varieties leading into the 2018 season.
Because the fungus is a sexually reproducing pathogen, it can adapt to varietal resistance and therefore growers need to be aware of the ratings before sowing. The guide is updated twice a year to provide growers with up-to-date and relevant information.
A buffer of 500m from the previous year’s canola stubble is suitable because the spores of the blackleg disease can transfer via wind and rain splash. Therefore, the impact of blackleg is higher in areas of intensive canola production.
Spore release from stubble will depend on autumn rainfall, with earlier spore release and possible increased disease severity resulting from higher rainfall.
2016 is an example when levels of blackleg infection were high, coinciding with a year of significant rainfall. Blackleg was also seen infecting pods in 2016 via aerial infection.
Also available to growers is the BlacklegCM app. BlacklegCM was developed by the Department of Primary Industries and Regional Development in Western Australia as part of the national pathogen management modelling and delivery of decision support project.
The app provides an indication of the likelihood and severity of Blackleg disease along with the associated yield loss and economic returns on a paddock-by-paddock basis. It takes into consideration the costs, yield benefits and grain prices and provides you with three outcomes, best, worst and most likely.
The app is based on and integrates 30 years of Blackleg research.
Another advantage of the app is the ability to compare profitability of different disease management strategies like paddock selection, variety choice, seed dressing, banded and sprayed fungicide.
The GRDC Blackleg Management Guide autumn 2018 edition is available on the GRDC website; www.grdc.com.au. The BlacklegCM app can be downloaded on iPad or Tablet from iTunes and Google Play.
This article was published in the Stock and Land, 3 May.
