Host Preference and Seedborne Transmission of Ditylenchus weischeri and D. dipsaci on Select Pulse and Non-Pulse Crops Grown in the Canadian Prairies.

The stem nematode Ditylenchus weischeri was recently reported on creeping thistle (Cirsium arvense) in Canada. Two greenhouse studies examined host suitability of crops commonly grown in the Canadian Prairies for D. weischeri and the closely related parasite of many crops, D. dipsaci. In the first study, common pulse crops (yellow pea, chickpea, common bean, and lentil), spring wheat, canola, creeping thistle, and garlic were evaluated. Plant biomass and reproductive factor (R = nematode recovered/inoculated) 8 weeks postinoculation were used to determine host suitability. Creeping thistle biomass was reduced by D. weischeri whereas D. dipsaci reduced biomass of four of five pea and two of three bean varieties. Two pea varieties were weak hosts for D. weischeri, with R slightly >1. D. weischeri aggressively reproduced on creeping thistle (R = 5.4). D. dipsaci reproduced aggressively on garlic (R = 6.4; a known host), moderately on pea varieties (R > 2), and weakly on chickpea and bean (R > 1). In the second study, using creeping thistle and yellow pea, D. weischeri was recovered from aboveground parts of the plants and seed of the former and D. dipsaci from the later. The results show that D. weischeri parasitizes creeping thistle but not other crops and that D. weischeri host preference is different from that of D. dipsaci.