Diversity and Pathogenicity of Root Rot Fungi from Canola () in Alberta, Canada.

Root rot disease poses a significant threat to canola (), underscoring the need for a comprehensive understanding of its causal agents for more effective disease mitigation. The composition and diversity of fungal pathogens associated with root rot of canola in Alberta, Canada, were evaluated from plant tissue samples collected in 2021 and 2022. The study revealed spp. as the predominant pathogens found in almost all surveyed fields. , , and were among the most frequently recovered species. Greenhouse trials confirmed their pathogenicity, with and found to be particularly aggressive. Additionally, and were identified for the first time as canola root rot pathogens. Inoculation with isolates of most species resulted in significant reductions in seedling emergence, plant height, and shoot and root dry weights. Analysis of translation elongation factor 1-α (TEF-1α) and internal transcribed spacer (ITS) sequences confirmed the identity of the spp., while concatenating the ITS and TEF-1α sequences enabled improved species differentiation. Geographic and year effects did not influence fungal diversity or aggressiveness, as determined by principal component analysis. This study emphasized the high diversity and impact of spp. in causing canola root rot.