Pest description and crop damage The adult cabbage seedpod weevil (CSW) is ash-grey to black and approximately 4 mm (1/6 in) in length. Like all weevils, it has a snout that resembles an elephant's trunk. Larvae are white, C-shaped and legless and can be found only within the pod. Over-wintering adults enter canola near flowering and may feed on the flower buds, resulting in blasting. Summer-emerging adults can also cause injury by feeding directly on the green pods of later-planted fields. Pod-feeding by the larvae can cause up to 35% yield loss. They also vector alternaria leaf spot on the pods, which is common in Canada and moving into the Palouse region of the PNW. Control measures need to be taken if 20 or more adults are collected in ten 180-degree (side-to-side) sweeps.
Management-chemical control (Foliar Treatment)
- bifenthrin (Bifen 2 AG Gold, others) at 0.033 to 0.04 lb ai/a or 2.1 to 2.6 fl oz/a. Do not exceed 0.08 lb ai/a or 5.12 fl oz per acre per season. Do not apply less than 14 days apart.
- chlorantraniliprole (Besiege, others) at 5.0 to 10.0 fl oz/a. Do not exceed a total of 28.0 fl oz of Besiege or 0.09 lb ai of lambda-cyhalothrin-containing products or 0.2 lb ai of chlorantraniliprole-containing products per acre per year. PHI 21 days. Minimum interval between applications is 5 days. If adjuvants are used, use only a non-ionic surfactant (NIS).
- cyhalothrin-gamma (Declare) at 0.0075 to 0.015 lb ai/a. PHI 7 days. Do not apply more than 0.045 lb ai per acre per season.
- deltamethrin (Delta Gold) at 0.009 lb ai/a. Do not apply more than 1.5 fl oz of Delta Gold per acre on canola in one growing season. Do not apply within 7 days of harvest.
- lambda-cyhalothrin (Lamda-Cy AG) at 0.015 to 0.03 lb ai/a. PHI 7 days. Do not apply more than 0.09 lb ai (0.72 pt or 11.52 fl oz of product) per acre per year. Do not apply within 7 days of harvest.
- zeta-cypermethrin (Mustang Maxx) at 4.0 fl oz/a (0.025 lb ai/a). PHI 7 days. Do not apply more than 24 fl oz of product (0.15 lb ai) per acre per season. Do not make applications less than 7 days apart.
Management-chemical control (Seed Treatment)
- imidacloprid (Gaucho 600) at 15.36 to 25.6 fl oz per 100 lb of seed. Larvae suppression only. Do not graze for feed.