A whole of industry approach to the assignment of stripe rust, stem rust and leaf rust disease response ratings to Australian wheat cultivars

A whole of industry, co-ordinated system for the assignment of reliable stripe rust, stem rust and leaf rust disease response ratings of current wheat cultivars and advanced breeding lines was developed to meet the needs of the Australian grains industry. Previously there was a lack of national consistency in ratings with each state independently publishing response ratings. However, privatisation of public wheat breeding during the early 2000s, recurrent stripe rust epidemics following a foreign pathotype incursion in 2002, and the dramatic increase in fungicide use provided the impetus to develop a consistent approach to assignment of ratings. Factors that became critical to the process were: 1) access to dedicated rust nurseries in diverse cereal production environments, 2) use of single seed sources for consistent variety identity, 3) control lines that provided consistent rust responses in field nurseries across regions, 4) a centralised repository of current and historical data (provided by the National Variety Trials program), and 5) pathotype identification (provided by the Australian Cereal Rust Control Program (ACRCP)). This system was subsequently documented by the Cereal Pathology Working Group (a sub-committee of the ACRCP consultative committee) and included a dispute resolution process. Currently, with GRDC funding, approximately 200 lines comprising current cultivars and advanced breeding lines, are assessed nationally in dedicated rust nurseries by members of the Working Group. Both current and historical data are reviewed annually by the Working Group with consensus rust responses developed and then scrutinised by wheat breeding companies prior to public release. This whole of industry system has improved timeliness, reliability and consistency of information with ratings used widely by Australian farmers to select cultivars to minimise losses due to rust and to plan appropriate chemical control strategies should resistance be inadequate.