Revised Spring 2016
Blackleg resistance group screening by Marcroft Grains Pathology and the University of Melbourne identified the cultivar GT42 with a new source of blackleg resistance allocated Group I. Recent screening data using lab generated blackleg isolates now indicates that cultivar GT42 has a unique combination of previously known resistance genes and will now be allocated resistance group ABDF. The cultivar GT42 has been screened in field blackleg nurseries and rated as Resistant (R) the highest possible rating. The cultivar GT53 which was previously also allocated to Group I resistance has not yet been screened against the new lab isolates. For more information please consult the Blackleg Management Guide.
Quantify the risk, paddock by paddock
Blackleg is a sexually reproducing pathogen that will overcome cultivar resistance genes. Fungal spores are released from canola stubble and spread extensively via wind and rain splash. The disease is more severe in areas of intensive canola production.
Blackleg can cause severe yield loss, but can be successfully managed. Use this guide to determine whether you are in a high-risk situation and what practices you can change to reduce or prevent yield loss from blackleg. Follow the four steps, in sequence, contained in this guide.
- Never sow your canola crop into last year's canola stubble.
- Monitor your crops in Spring to determine yield losses in the current crop.
- Choose a cultivar with adequate blackleg resistance for your region.
- Relying only on fungicides to control blackleg poses a high 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.
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