The Weevils Are Coming: What Canola Growers Need to Know About Cabbage Seedpod Weevil

Cabbage seedpod weevil (CSPW) pressure was elevated in parts of our region last year, and this season is shaping up to be another one to watch. The 2025 Prairie-wide CSPW survey detected weevils across the region — which means every canola field is worth monitoring this year, regardless of what pressure looked like in 2024. Our scouts are already seeing weevil activity in some fields ahead of peak flowering.

How Weevils Move In

to Canola

CSPW are attracted to yellow, so populations typically build in canola fields as flowering begins. Before that, they feed on early-flowering brassicaceous weeds — like flixweed — and on canola buds. Keeping an eye on fields as they approach flowering is important, since weevils can be present and feeding before the crop hits the stage where economic damage really starts.

Where the Economic Damage Happens

Almost all yield loss from CSPW comes from adult weevils laying eggs in young pods. Each larva can consume up to five seeds, and damaged pods are more prone to shattering at harvest and fungal infection. The economic threshold is an average of 25–40 adult weevils per 10 sweeps across the field.

Getting the Spray Timing Right

Timing a CSPW application well is critical — both for efficacy and for protecting pollinators. Spraying is recommended when the crop is at 10–20% flower and the first pods have reached about 1" in length, which is when egg-laying begins. Spraying too early reduces control, since weevils will continue moving into fields as more of the crop comes into flower. Waiting for the right crop stage gives you the best chance of a single well-timed application doing the job.

Talk to your agronomist about CSPW pressure in your area and whether your fields warrant scouting and a spray decision this season.

Ag Grow Consulting provides independent agronomy services across Saskatchewan. Our agronomists work directly with growers through every stage of the season.