Grower-submitted canola samples support collective efforts to manage blackleg

Clipping canola stems to check for blackleg Clipping canola stems to check for blackleg Clipping canola stems to check for blackleg Clipping canola stems to check for blackleg

Overview of blackleg in canola

Although symptoms can sometime be confused with sclerotinia stem rot or verticillium stripe, blackleg has been a major disease of canola in the Canadian Prairies for several decades. Prevalence and incidence of blackleg (primarily caused by the fungal pathogen Leptosphaeria maculans in Canada) varies between years, but favourable environmental conditions can cause a significant impact on canola yields. A detailed look at the population of the pathogen causing blackleg (and the evolution or adaptation it has gone through) is covered in the 2021 ‘We stand on guard for thee: A brief history of pest surveillance on the Canadian Prairies’ publication.

Genetic resistance was originally introduced in the 1990s and had good success. However, this solution alone wasn’t enough to eliminate the disease. Current management strategies encourage an integrated approach- of which new blackleg resistance is still a key component- for growers in Canada and for our international customers (as is highlighted in Keep it Clean). Some of the key research findings which continue to inform improvements in blackleg management are shared in the projects below.

Blackleg disease cycle in canola

Key advancements for the blackleg management toolkit

The ‘Canola Disease Management Tools for the Prairies – Blackleg and Sclerotinia’ project, which was made up of several studies, reported these advancements (amongst others):

Canola stems with varying levels of blackleg

Interestingly, the ‘Understanding the mechanisms for race-specific and non-specific resistance for effective use of cultivar resistance against blackleg of canola in Western Canada’ research found that quantitative resistance (QR) plays a role for R-rated canola cultivars. These QR traits are highly useful for blackleg management in Western Canada, even under warmer temperatures between the rosette to early flowering stages.

In addition, Yu’s ‘Introgression of disease resistance from Brassica nigra into canola using new-type Brassica napusstudy used black mustard (B. nigra), which is highly resistant to canola diseases, to find new sources of blackleg resistance genes. They were able to successfully transfer those genes into B. napus breeding lines and made them available to canola breeders.

Further examination of blackleg management topics

Additional completed blackleg-related projects investigating aspects of management include:

Blackleg research conclusions has informed management advice, in many forms

Investigation of blackleg through multiple years of research has increased the knowledge of blackleg, which has fueled the development of many grower resources, both directly via:

Outcomes of multiples studies have also been combined and applied to commercial situations, to provide recommendations directly to canola growers through:

What growers can do (without any cost) to support blackleg knowledge

In addition to the provincial disease surveys that are completed each year by a combination of government and industry members, and research conducted on incidence and distribution of blackleg (see A six-year investigation of the dynamics of avirulence allele profiles, blackleg incidence, and mating type alleles of Leptosphaeria maculans populations associated with canola crops in Manitoba, Canada for details), canola growers can contribute to the understanding of blackleg by testing their fields.

Submitting samples of disease-infected canola stubble helps growers confirm the presence of blackleg in their field and (if present) to determine what blackleg races exist in a field. This allows growers to make an informed decision about which cultivar they should select in the following year (to best manage their blackleg). In addition, these results provide useful information to the province about the prevalence and distribution of blackleg and specific L. maculans races. Some provinces even offer free tests for canola growers.

  • Members of the Manitoba Canola Growers can currently submit samples for free to the Pest Surveillance Initiative (PSI) lab (in Manitoba). PSI also provides the phenotype – how the races in a field may affect the cultivar resistance in that field – to help guide cultivar selection. For details on the submissions, see this PSI Lab information.
  • Similarly, SaskCanola is now offering free blackleg disease testing program for registered canola growers in Saskatchewan. See this SaskCanola page for details on how to collect and submit samples to Discovery Seed Labs, as well as results to expect.
  • The Alberta Plant Health Lab offers blackleg testing options in Alberta- including some opportunities for free sample submissions.
  • Private labs that can also offer blackleg testing are listed here.

Future findings to anticipate

The ongoing need for blackleg-related information continues to incite new research on this topic. Check out the focus and objectives of these projects, which are currently under way:

More canola disease-related studies are available on the Canola Research Hub.

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