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

Abstract

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 (Rf = 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 Rf slightly >1. D. weischeri aggressively reproduced on creeping thistle (Rf = 5.4). D. dipsaci reproduced aggressively on garlic (Rf = 6.4; a known host), moderately on pea varieties (Rf > 2), and weakly on chickpea and bean (Rf > 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.

Monoxenic rearing of Ditylenchus weischeri and D. dipsaci and microplot examination of the host suitability of yellow pea to D. weischeri

“…This result is in agreement with the results from a previous greenhouse study (Hajihassani et al 2016), which demonstrated that though D. weischeri is capable of invading yellow peas, the ability of the nematode to reproduce on the plant is negligible. Further, the failure to reproduce on plants was not due to Pi.…”

“…Similarly, we reported recently that D. weischeri was unable to infect seed-pods and seed of yellow pea cv. Agassiz grown under greenhouse conditions (Hajihassani et al 2016). In the present study, the increasing D. weischeri population had no impact on yellow pea growth and yield at most of the nematode densities, however, slight reductions were observed in plant height, shoot biomass, and pod length of yellow pea varieties Agassiz and Bronco at Pi of 1200 and 3200 nematodes/plant.…”

“…A microplot study was conducted at the University of Manitoba Point Research Station in Winnipeg to determine the effect of different population densities of D. weischeri on growth and yield of field-grown yellow pea. Two varieties of yellow pea, Agassiz and Bronco, were examined having previously the highest (1.6) and the lowest (0.9) reproduction factor (Rf ) value for D. weischeri, respectively, of five varieties examined under greenhouse conditions (Hajihassani et al 2016). A 4 × 8 m section of the field was used in the present study.…”

“…Results of greenhouse assays showed creeping thistle to be a host (Hajihassani et al 2016) and lentil (lens culinaris L.), chickpea (Cicer arietinum L.), common bean (Phaseolus vulgaris L.), garlic (Allium sativum L.), spring wheat (Triticum aestivum L.), canola (Brassica napus L.), onion (Allium cepa L.) and strawberry (Fragaria × ananassa) not to be hosts (Chizov et al 2010;Hajihassani et al 2016). Recently, under greenhouse conditions, we reported that D. weischeri reproduced slightly (1 < reproduction factor < 2) on cvs Agassiz and Golden yellow pea (Pisum sativum L.) without producing any symptoms on the plants (Hajihassani et al 2016). We recovered D. weischeri from stems and leaves of plants, indicating that the nematode was not a seed-borne parasite of yellow pea.…”

“…Rearing of D. weischeri has relied upon cultures of greenhouse-grown creeping thistle (Hajihassani et al 2016). Rearing on creeping thistle requires a great deal of planning, labour, and resources for mass production and extraction from a lot of plant tissues.…”