LAUSR

The ability of the recently described stem nematode of creeping thistle (Cirsium arvense L.), Ditylenchus weischeri, to develop on and parasitize yellow pea (Pisum sativum L.) is uncertain. The current study examined nematode life-stage progression and generation time on yellow pea as affected by temperature with the related pest, D. dipsaci, used as a positive control. Relationships for body length of the two nematode species and life stage were unaffected by rearing on plant hosts compared with carrot disks. Then plant-reared J4 individuals of both nematode species were used to determine the effect of temperature (17, 22, and 27°C) on life-stage progression and minimum generation time with yellow pea. At 17 and 22°C, D. weischeri J4 individuals progressed to only the adult stage whereas, at 27°C, the minimum generation time from J4 to J4 was 30 days or 720 growing degree-days. The minimum generation time for D. dipsaci was 24, 18, and 22 days or 336, 342, and 528 growing degree-days at 17, 22, and 27°C, respectively. The results indicate that development of D. weischeri is temperature dependent and reproduction is unlikely on yellow pea in the Canadian Prairies, where mean daily air temperatures of 27°C are rare and not sustained.