Pest description and crop damage Active, white, fragile, centipede-like soilborne relatives of insects, 0.25 inch long, with 12 or more pairs of legs. They damage sugar beet primarily early in the season by feeding on germinating seed or on small roots of seedling plants. Symphylans are in unpredictably spotty infestations and generally are considered minor pests.
No formal economic thresholds exist for insecticide treatment decisions. No effective "rescue" treatments for symphylans can be applied postemergence in sugar beet seed fields.
- chlorpyrifos (Lorsban Advanced)-Oregon only. Restricted to one of the following two types of uses: either one pre-plant broadcast application at 1.88 lb ai/a and incorporated into the top 4 inches of soil -or- one at-planting/transplanting application at 0.94 lb ai/a as 5- to 7-inch band over row and incorporated into the top 2 to 4 inches of soil. 24c SLN OR-090007 (expires 12/31/2023).
- ethoprop (Mocap EC) at 2 to 3 lb ai/a pre-emergence for control or post-emergence for suppression. 24c SLN
- OR-120006 (expires 12/31/2023). Oregon only.