Avoid blackleg fungus
The latest blackleg ratings for canola cultivars have been made available to the nation’s grain growers.
Marcroft Grains Pathology principal Steve Marcroft, who is co-ordinator of the Grains Research and Development Corporation’s National Canola Pathology Program investment, said results from the latest blackleg screenings of canola cultivars had been factored into the updated blackleg ratings for 2018.
‘‘Blackleg ratings can change from year to year if the fungus overcomes cultivar resistance, so it is important growers refer to the latest ratings when planning their cropping programs,’’ Dr Marcroft said.
‘‘Blackleg can cause severe yield loss, but can be successfully managed.
‘‘Growers are therefore advised to closely follow the recommended strategies for reducing the risk of disease which are contained in the GRDC Blackleg Management Guide.’’
The guide can be used by growers to determine whether they are in a high-risk situation and what practices they can change to reduce or prevent yield loss from blackleg. These practices include: ■ Never sowing your canola crop into last year’s canola stubble.
■ Avoiding sowing your canola crop adjacent to last year’s canola stubble.
■ Choosing a cultivar with adequate blackleg resistance for your region.
■ Only using fungicides if there is a high probability of yield loss — sowing next to last year’s canola stubble and/or sowing a cultivar with a low blackleg rating. Relying only on fungicides to control blackleg poses a risk of fungicide resistance.
■ If your monitoring has identified yield loss and you have grown the same cultivar for three years or more, choose a cultivar from a different resistance group.
■ Monitoring your crops in spring to determine yield losses in the current crop.
The new BlacklegCM blackleg management app has also been updated with the latest disease ratings.
The app, a GRDC investment, provides growers with a tool that can forecast the likelihood and severity of the disease, associated yield loss and economic returns on a paddock-by-paddock basis ahead of sowing.
The app, available for use on tablets via Apple’s App Store and the Google Play Store, is an extension of the GRDC Blackleg Management Guide which is updated twice a year to reflect any changes in the resistance status of individual cultivars.
Dr Marcroft said the severity of disease in 2018 was dependent on seasonal conditions. ■ Comprehensive information on management of canola diseases can be found in the GRDC’s Diseases of Canola and Their Management: The Back Pocket Guide, which can be downloaded via: https://grdc.com.au/GRDCBPG-CanolaDiseases ■ The blackleg ratings are contained in the GRDC’s Blackleg Management Guide autumn 2018 edition, available at: https:/ /grdc.com.au/GRDC-FSBlacklegManagementGuide