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CFCRA Soybean Cluster; Activity 9: Strategies for effective and durable management of Phytophthora and root rot complexes of soybean

Principal Investigator: Debbie McLaren and Stephen Strelkov  

Research Institution: Agriculture & Agri-Food Canada and University of Alberta


Timeline: April 2018 – March 2023  

Objectives:

  • Surveys on the occurrence of Fusarium, Rhizoctonia and Pythium fungal spp. and the soybean cyst nematode (SCN) in western and eastern Canada.
  • Monitor the spread of sudden death syndrome (SDS) in Ontario and establish a nursery to screen for SDS tolerance.
  • Utilize advanced PCR analysis of root rot pathogens (e.g., droplet digital PCR), which enables highly precise quantification of target DNA.

Impacts:

  • Results provided a deeper understanding of the incidence and spread of root rot diseases associated with the Fusarium spp. complex and other emerging pathogens and can be used to develop management strategies for these diseases affecting soybean across Canada.

Scientific Summary:

Throughout Canada, new root diseases of soybeans continue to emerge and spread. Pathogens that cause well established root diseases continue to evolve. For these reasons, it is important to monitor root diseases throughout Canada in a systematic way. This activity expanded coordinated surveys for current and emerging soybean root pathogens across Canada. The disease surveys uncovered new information on the causes of soybean root diseases as well as the factors influencing their incidence and severity. 

Results:

  • Coordinated surveys were carried out annually from 160 fields across Canada (Alberta, Saskatchewan, Manitoba, Ontario, Quebec and Prince Edward Island).
  • Root rot was confirmed in 100% of the fields assessed.
  • Results indicated that root rot was caused primarily by Fusarium species (F. oxysporum, F. redolens, F. graminearum, F. solani, F. avenaceum, and F. acuminatum) and the newly identified Macrophomina phaseolina.
  • The pathogenicity of these main species was assessed on a suite of 20 soybean cultivars. The level of resistance varied, suggesting the feasibility of a gene pyramiding approach for resistance to Fusarium root rot and wilt on soybean.
  • SCN was not identified at quantifiable levels in any of the field samples submitted from outside of Ontario (55 total), indicating slow expansion of SCN in new soybean producing areas.
  • SDS disease screening nurseries were established at AAFC Harrow, and in an infested field near Chatham, Ontario. Several lines were tested at these locations from 2020-2022 (57,110 and 127 varieties), with varying levels of tolerance.
  • An advanced molecular diagnostics technique based on droplet digital PCR (ddPCR) was developed for the predominant Fusarium spp., enabling precise quantification of the pathogen in fields, indicating expansion.

Overall, the findings from this research activity provided a deeper understanding of the incidence and spread of root rot diseases associated with the Fusarium spp. complex and other emerging pathogens and can be used to develop management strategies for these diseases affecting soybean across Canada.

External Funding Partners:

Funding for the Soybean Cluster was provided by the Agriculture and Agri-Food Canada AgriScience Program through the Canadian Agricultural Partnership, with industry support from the Canadian Field Crop Research Alliance (CFCRA) whose members include: Atlantic Grains Council; Producteurs de grains du Quebec; Grain Farmers of Ontario; Manitoba Corn Growers Association; Manitoba Pulse & Soybean Growers; Saskatchewan Pulse Growers; Prairie Oat Growers Association; SeCan; and FP Genetics.

Project Related Publications:

Kim, Y. M., McLaren, D. L., and Strelkov, S. E. 2024. First report of charcoal rot on soybean caused by Macrophomina phaseolina in Manitoba, Canada. Plant Dis.108:522.

King, C. 2024. A widespread and increasing concern: A nationwide study is giving us a better handle on current and emerging soybean root diseases. Top Crop Manager. 50(4).

Qian, B., Smith, W., Jing, Q., Kim, Y.M., Jégo, G., Grant, B., Duguid, S., Hester, K., and Nelson, A. 2023. Climate conditions in the near-term, mid-term and distant future for growing soybeans in Canada. Canadian Journal of Plant Science. 103: 161-174. Wu, L., Hwang, S.F., Strelkov, S.E., Fredua-Agyeman, R., Oh, S., Bélanger, R.R., Wally, O., and Kim, Y.M. 2024. Pathogenicity, host resistance and genetic diversity of Fusarium species under controlled conditions from soybean in Canada. Journal of Fungi. In Special Issue: Fusarium spp.: A Trans-Kingdom