As canola starts to bolt and produce flowers, producers should consider checking to see if they have a tiny weevil known as the Cabbage Seedpod Weevil (CSPW), (Figure 1.) waiting to potentially impact yields. To find out if CSPW needs to be treated, fields should be scouted twice a week starting when plants are 10-20% bloom and continued through the flowering period. For B. napus canola varieties this will equate to 10 to 16 flowers on the main stem. For B. rapa varieties, this will equate to 6 to 12 flowers on the main stem. Using a heavy canvas sweep net, take 10 sweeps starting 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.
An insecticide application is warranted when 30 to 40 adult weevils are collected from the 10 sweeps. The Canola Council of Canada has recently lowered the above-mentioned threshold to 20 weevils in 10 sweeps. For more information about this pest, i.e., what it looks like and the biology and impact to canola production, check out the WSU Extension Fact Sheet titled, “Cabbage Seedpod Weevil Management in Canola.”
For questions or comments, contact Dale Whaley by email at firstname.lastname@example.org or by phone at 509-745-8531.