The use of resistance genes is one of the major strategies for minimising the impact of blackleg disease of canola. Therefore, the accurate identification of resistance genes in Australian canola cultivars is essential for the continued high levels of canola production. All commercial cultivars are released with associated resistance groups, allowing growers to select and rotate cultivars with different sources of resistance to minimise the impact of blackleg disease. The identification of resistance genes, and therefore the classification of Australian cultivars into resistance groups, requires phenotypic screening using a set of precisely defined differential isolates of the blackleg fungus and cultivars that have been characterised for all known genes involved in disease. This project will maintain and further improve the set of pathogen isolates and host lines, as well as screen all commercially released canola cultivars each year. Furthermore, the differential set will be expanded to incorporate new isolates or lines as needed when new sources of resistance are identified. These differential sets will also be provided to programs to enable delivery of other research, such as the identification of molecular markers for resistance genes and identification and characterisation of quantitative (adult plant) resistance.