Blackleg Is A Black-Gold Loving Pirate And It Is Here To Steal Your Canola Yield!

Blackleg is known for its ability to survive on canola stubble in the soil as a persistent threat for 3-5 years. Without effective management strategies, the disease can lead to repeated crop failures, further compounding the issue. Additionally, the economic implications are substantial; blackleg can reduce yield by 10% or up to 50% or more in severely affected fields, leading to significant financial losses.

In the growing season of 2024, Pitura Seed Farms learned a few new lessons regarding Blackleg on our farm:
1.       We determined the races of blackleg present on our farm and can use variety selection as a primary defense against the disease.
Pitura Seed Farms had the stubble for 2 canola fields tested for presence of Blackleg and Verticillium in September 2024. Our samples came back with 100% of stems infected with Verticillium and a range of 30-65% stems infected with Blackleg. Below is an example of what the sample results will look like.

**Important** – the percent infection results from the tests can not be fully accurate for the field. Only a few stems are taken from a whole field to sample for Blackleg. Blackleg is a disease that can be localized so the results can be quite variable. The important information on the test is the determined Blackleg Race Phenotype. Knowing what blackleg races are present on our farm is valuable in selecting a variety with a matching resistance group (See lock and key article) – for example, BY 7204 LL canola from Brett Young has the E2 resistance group which will provide protection on our farm based on these results.

2.       Seed treatment is the secondary defense to use against blackleg.
Early season infection at the cotyledon stage is responsible for contributing to the SEVERITY of the disease within a field and cause the most significant damage to yield compared to late season infection. Choosing a canola variety that comes treated with a product such as Helix® Saltro® seed treatment (which has dual action protection against blackleg) will be highly active on blackleg and helps protect cotyledons at emergence. Saltro is the only seed treatment options that offers protection against air-borne blackleg pathogens, while also protecting against seed borne. The Helix component backs that up with a second action against seed-borne blackleg.

Photo from Syngenta Canada

3.       Use of in-crop fungicides where necessary.
On a field that had history of Blackleg in previous canola crops, we applied a foliar fungicide at 2-6 leaf stage given that the conditions were ideal for disease development. It is hard to quantify if this application paid. Ideally, it will at least reduce the fungal load within the stubble of that field which will reduce the severity of infection for future years. We also consider flea beetle pressure and whether those bite marks can act as entry points for disease (could be the case for Verticillium wilt). Some farmers will choose to spray a foliar fungicide on their crops following a lightly-damaging hail event. Should we be treating flea beetle damage similarly?

In conclusion, protecting canola crops from blackleg disease is crucial not only for preserving yields and profitability but also for ensuring the long-term sustainability of canola farming. By taking preventive measures and implementing a comprehensive management plan (maintaining a 3 – 5-year crop rotation, selection of correct resistant group varieties, use of seed treatments and in-season fungicide applications) farmers can effectively manage this threat and secure a healthier future for their crops.
~Katie Meggison