Host preference of Pratylenchus neglectus to major crops of the Prairie Provinces of Canada

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Wenyika, Priscillar
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Root lesion nematodes of the genus Pratylenchus Filipjev, 1936 are pests of economic importance worldwide. Pratylenchus spp. have recently been identified in soils from commercial fields in the Canadian Prairie Provinces, and there is a lack of knowledge about the host preferences of these nematodes. This research was conducted to determine: a) the crop hosts preferred by the Pratylenchus spp., b) the effects of selected pulse and non-pulse crops mainly grown in the Canadian Prairies in building-up densities of the nematode under growth chamber conditions, c) the effect of the nematode and population density over several crop growth cycles on performance of the plants, and d) the species identity of the Pratylenchus spp. Host suitability to Pratylenchus spp. was evaluated on the most widely grown varieties of selected pulse and non-pulse crops available in Canadian Prairies including canola, chickpea, lentil, pinto bean, soybean, Canada Western Red Spring Wheat, and yellow pea. Host status was assessed using the reproductive factor (Rf = final/ initial density) and plant growth parameters (plant height, above-ground, and root biomass) were measured at the end of each cycle. Nematodes recovered from the test soils and roots of host crops were identified using morphological identification and molecular assays. The suitable hosts for Pratylenchus (Rf >1) were canola, chickpea, pinto bean, soybean, and spring wheat. Soybean was the most preferred host for these nematodes with a mean above the threshold level for Pratylenchus spp. (>1000 nematodes per kg-1 of soil) in the final cycle. The population of Pratylenchus spp. in pots planted to canola, chickpea, pinto bean, soybean, and wheat significantly increased across the three growth cycles. Lentil was a poor host and yellow pea was a non-host for Pratylenchus spp. High densities of Pratylenchus reduced plant height, above-ground and root biomasses of canola, lentil, pinto bean, spring wheat, and yellow pea. Plant height and biomass of chickpea and soybean were not reduced by increasing Pratylenchus densities. The Pratylenchus spp. was identified as P. neglectus using morphometric characters, PCR with species-specific primers and DNA sequencing. Most of the crops mainly grown in the Canadian Prairies are hosts for P. neglectus.
root-lesion nematodes, pulse crops, Canadian Prairies, Host preference, Pratylenchus neglectus, wheat, canola, soybean, chickpea, yellow pea, Pratylenchus spp