If you have canola as part of your rotation and have not yet checked for the presence of Cabbage Seedpod Weevil (Ceutorhynchus obstrictus (Marsham)), then now is the time to do so! Treatment thresholds for this tiny, yet destructive pest, are 3 to 4 adult weevils per sweep or 30 to 40 per (10X) sweeps. I was northern Douglas County today (5-13-19) and collected 53 and 55 weevils while sweeping separate fields! Using a heavy canvas sweep net, start sampling at the edge of fields and work inwards as you go. Don’t be surprised if you only find this pest concentrated on field borders, but during outbreak infestations, it may be found throughout the entire field.
For more information about this pest, i.e., what it looks like and the biology and impact to canola production, and how to chemically treat it, check out the WSU Extension Fact Sheet FS224E Cabbage Seedpod Weevil Management in Canola.
Figure 1: CSPW in winter canola in Douglas County, WA. Photo by Karen Sowers.
For questions or comments, contact Dale Whaley by email at dwhaley@wsu.edu or by phone at 509-745-8531.