Response of winter canola cultivars to cabbage seedpod weevils

Canola (Brassica napus L.), a major global oilseed crop, is vulnerable to a wide range of insect pests, including cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham). This pest feeds on canola buds, flowers, and developing pods, resulting in significant yield reductions. In North America, infestation often exceeds 25% of the canola pods having exit holes, and yield losses on canola have been estimated at 5-30%. While chemical, mechanical, or biological methods are commonly used by producers, incorporating resistant cultivars can reduce crop losses by contributing to sustainable pest management. In this study, we assessed five winter canola cultivars (Durola, Erica, CP320W RR, Surfire.SURT’, and ‘Messi’) for their response to cabbage seedpod weevil (cspw) damage. Study trials are being conducted in 2024 and 2025 at three locations in Idaho. Randomized complete block design with four replications was used. Primary racemes with mature pods were collected from five randomly selected canola plants per plot. In the laboratory, pods were carefully examined for cabbage seedpod weevil exit holes, and each raceme was threshed to determine seed yield per raceme. In 2024, cspw exit holes differed among cultivars at Parker Farm but not at the other sites. In 2025, cspw exit holes did not differ among cultivars at any site. Location and location by year effects on cspw exit holes were significant.