Epidemiology and management of blackleg of canola in response to changing farming practices in Australia

The Australian canola industry was established in the 1970s and has expanded since that time, particularly in the last two decades. This review addresses the changes in farming practices since the year 2000 and the epidemiological and management consequences for blackleg, caused by the fungus Leptosphaeria maculans, the main disease impacting Brassica napus production. To help understand the change in production practices, a survey of over 100 growers and agronomists was conducted. Modern management practices include increased crop residue retention, frequency of canola in crop sequences, number of resistance genes in cultivars, use of hybrids and fungicides as well as earlier sowing and flowering times. While some of the changes identified in the survey and in this review increase the risk and severity of disease, including new symptoms like upper canopy infection, others provide novel strategies for control. Keeping these changes in mind, a set of research priorities towards long term sustainable management of blackleg disease are identified.