Importance and causal agents of root rot on field pea and lentil on the Canadian prairies, 2014-2017

摘要

Surveys of pulse crops across the Canadian prairies were undertaken between 2014 and 2017 to assess the distribution and severity of root rot of field pea and lentil, to identify the most important causal agents, and to compare the efficiency of culturing techniques with multiplex PCR. Root rot was present in every pea and lentil field surveyed in all three provinces. When assessed based on province and soil zone, moderate to severe symptoms (severity amp; 3 on a 1-7 scale) occurred in 25-99 of pea fields, but only 8-34 of lentil fields. Root rot severity on both crops was higher in growing seasons with high precipitation and was lower in drier years, but only lentil showed any difference associated with soil zone, with lower severity in the brown soil zone. This study demonstrated that Aphanomyces euteiches occurs across the Prairie region, where it caused moderate to severe injury on many field pea crops. Fusarium avenaceum was the most common pathogen identified in both culturing and PCR analyses, but other Fusarium spp., together with Pythium spp. and Rhizoctonia solani, were also components of the complex. Use of PCR for pathogen identification routinely resulted in identification of many pathogens from an infected root, whereas culturing and isolation resulted in only one or two pathogens per root. PCR was extremely important for assessing the impact of A. euteiches, which was almost never identified using culturing approaches. This observation explains why A. euteiches was not initially recognized as an important pathogen of pulses in the region.