Investigating interactions of ascospores and pycnidiospores with blackleg resistance in canola and efficacy of seed applied fungicides in these specific interactions in western Canada
Term: 3 years, ending March 2024
Status: Complete
Researcher(s): Dilantha Fernando, Shuanglong Huang U of M; Gary Peng, AAFC
SaskCanola Investment: $214,600
Total Project Cost: $214,600
Funding Partners: n/a
Grower Benefits
Genetic resistance is the most promising strategy for canola growers to adopt in dealing with blackleg.
Canola residue management is still very important as the presence of ascospores and pycnidiospores are both found in western Canada.
Project Summary
This is the first investigation into the infection by pycnidio- and asco-spores, as well as a mixture via wounds under the influence of cultivar resistance and fungicide seed treatment for blackleg disease in canola. The findings from this study suggested that it is feasible to produce ascospores and pycnidiospores in the lab and use these types of spores to test canola materials for blackleg resistance in both controlled environment and field conditions. This research is important for the canola industry as we have successfully developed approaches to produce ascospores and pycnidiospores and established the capacity to investigate the aggressiveness of ascospores, pycnidiospores, and a combination of the two against the canola lines that are currently available on the market.
Three approaches were developed, and one of these three approaches was optimized to produce ascospores and pycnidiospores in the lab. These ascospores and pycnidiospores were then used to elucidate the interactions of ascospores and pycnidiospores with commercial canola varieties in controlled environments. A panel of 17 commercial canola lines acquired from seed companies were inoculated with ascospores, pycnidiospores and a combination of the two and assessed for seedling and quantitative resistance, following standard cotyledon inoculation method for seedling resistance (Zhang et al. 2016) and petiole inoculation method for quantitative resistance (Huang et al. 2014). In the meanwhile, these ascospores and pycnidiospores were also used to evaluate the efficacy of seed applied fungicides against the infection by ascospores and pycnidiospores influenced by genetic resistance under field conditions.
The field experiments were carried out in Carman MB and Melfort SK for the two years 2022 and 2023. The results from this project indicated that, the mixture of ascospores and pycnidiospores exhibited the greatest aggressiveness level, followed by ascospores and pycnidiospores respectively, against blackleg infections in both in-door and field conditions. When the inoculums were directly applied through fresh wounds, the efficacy of Fluopyram seed treatment improves, this corroborates with previous findings (Peng et al. 2020; Huang et al. 2023), but not when canola plants were infected with natural inoculums (Huang et al. 2024). Taken together, the findings from this study not only suggested that, genetic resistance is the most promising strategy for canola growers to adopt in dealing with blackleg disease, but most importantly another key discovery from this study is, as a mixture of ascospores and pycnidiospores have shown the greatest aggressiveness against blackleg infections, the optimization of canola residue management becomes more important as the presence of both ascospores and pycnidiospores is most likely the case in western Canada. However, more future research is required to generate new data and provide data-driven recommendation about the presence of both ascospores and pycnidiospores, and what are the composition of these two types of spores across the prairie provinces where canola is intensively grown, in the face of blackleg challenges (Canadian Plant Disease Survey, 2023).