Identify verticillium stripe as the first step to effective management

Verticillium stripe of canola is caused by the fungal species Verticillium longisporum and is a fairly new in western Canada. It is one of the diseases that surveyors watch for in their annual Manitoba, Saskatchewan and Alberta disease surveys and canola growers are concerned about potential yield loss that it may cause. While research has been conducted on verticillium stripe in canola, there are still many knowledge gaps related to this disease and the impact it has on canola.

The five-year (2019-2024) Verticillium Stripe – The Disease Management project, led by Dr. Hwang and Dr. Strelkov, investigated the disease development, evaluated canola genotypes for resistance and examined its interactions with blackleg. It aimed to help farmers and industry predict the impact of this disease, facilitate further research into verticillium stripe more efficiently and to more effectively screen genetic material for resistance to the pathogen.

More specifically, the project objectives include:

1)  Measure yield loss by evaluating the the effects of inoculum density on disease intensity was evaluated and creating a model to related these two factors.

2) Quantify the effects of inoculation at different growth stages of canola and using different techniques.

3) Evaluate canola genotypes for resistance to verticillium stripe.

4) Determine the interacting effects of verticillium stripe and blackleg.

Methods

Researchers measured yield losses in two ways: on a per-plant basis by growing plants in micro-plots inoculated at different densities, and by growing plants in six by 1.5 metre field plots harvested by small-plot combine. They used greenhouse experiments to determine interactions between blackleg and verticillium stripe.

Weather conditions were moister than average in the early growing season and resulted in good disease development in the 2020 field experiments. In 2021, precipitation was well below average in June and July and resulted in much lower disease development, however yield losses still occurred.

Results
Verticillium stripe infecting canola in the early stages inhibited canola establishment and growth. Later infection led to deterioration of the stem and vascular tissues. Infection at both stages affected yield and yield loss increased as the infections became more severe.