Survey of Plant-Parasitic Nematodes in Pulse Crop Fields of the Canadian Prairies
Fernanda, Gouvea Pereira
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Gouvea Pereira, Fernanda. M.Sc., University of Manitoba, December, 2018. Survey of Plant-Parasitic Nematodes in Pulse Crop Fields of the Canadian Prairies. Advisor; Dr. Mario Tenuta. The current distribution of economically important plant parasitic nematodes is relatively unknown in the Canadian Prairies for pulse crops. The majority of previous surveys were done several decades ago and may now be suspect as a result of recent molecular identification methods; as has been the case with the quarantine pest Ditylenchus dipsaci (Kühn) Filipjev. The nematode species Ditylenchus dipsaci can constrain export markets for economically important crops, such as peas. However, a more recent study has revealed that previous identifications of D. dipsaci in yellow pea (Pisum sativum L.) exports have actually been the non-quarantine species Ditylenchus weischeri Chizhov, Borisov & Subbotin. To further our understanding of these issues, a survey was conducted in three major pulse crops growing regions of Canada (Alberta, Saskatchewan and Manitoba) to determine the occurrence of plant-parasitic nematodes associated with pea, chickpea (Cicer arietinum L.) and lentil (Lens culinaris L.). A total of 465 plant and soil samples of pea, chickpeas, lentils and creeping thistle (Cirsium arvense L.), plants from 93 fields were analysed. Recovered nematodes were identified to genus by morphological features. Molecular analysis by species-specific PCR, PCR-RFLP and sequencing of the ITS (ITS1 + 5.8S + ITS2) of the rRNA gene were also used to identify recovered nematodes to species. Twenty genera of plant-parasitic nematodes were recovered from the soil and (or) the plants of pea, chickpea, lentil and creeping thistle, including Anguina, Aphelenchoides, Ditylenchus, Helicotylenchus, Hoplolaimus, Longidorus, Merlinius, Paraphelenchus, Paratylenchus, Pratylenchus, Subanguina, Paratrichodorus, Tylenchorhynchus and Xiphinema. 2 Several fields had high density of plant-parasitic nematodes belonging to the genera Ditylenchus, Pratylenchus, Paratylenchus, Helicotylenchus and Tylenchorhynchus, which could be potentially problematic for the crops studied or for crops that are grown in rotation. Molecular analysis results indicate the recovery of D. weischeri, D. dipsaci, Pratylenchus neglectus (Rensch) Filipjev & Schuurmans-Stekhoven, Xiphinema rivesi Dalmasso and Paratylenchus nanus Cobb. Ditylenchus weischeri, a parasite of thistles and not crops, was recovered from 22 fields across Alberta, Saskatchewan and Manitoba. D. dipsaci was recovered from pods of one yellow pea field in Manitoba. These results confirm the high prevalence of D. weischeri on creeping thistle in pulse fields and the near absence of D. dipsaci.