Pest description, crop damage and life history
Pest monitoring Infested soil can be treated with insecticides, but the effect is limited because of the symphylan's ability to migrate deep into the soil. Insecticides may help give the plants a chance to establish in a protected zone. In Oregon, 10 to 20 symphylans per young bean plant were shown to affect plant growth. In general, preplant field evaluation for symphylans involves grid sampling at one acre intervals, digging 6 inch by 6 inch by 12 inch holes (0.25 cubic foot), spreading and carefully examining the soil from the hole, and using an action threshold of 0.5 to 1 symphylans per sample. Many organisms prey on symphylans in the field, including true centipedes, predatory mites, predaceous ground beetles, and various fungi. However, little is known about their effect on symphylan populations.
Symphylan damage generally is associated with soils that are high in organic matter content and have good soil structure. Symphylans do not thrive in either compact or sandy soils, because these soils do not provide them with adequate tunnels for their movement (symphylans cannot make their own burrows). There is some evidence that packing down the soil surface after planting may reduce injury. There is some evidence that aggressive tillage, especially roto-tillage suppresses symphylan activity for the same reasons stated above.
Flooding for 2 to 3 weeks has controlled symphylans in some situations but has been unsuccessful in others. Even in the best circumstances, flooding only reduces populations, and they can increase when conditions are again favorable. Effectiveness of rotations with non-host crops has not been studied.
Management-chemical control: HOME USE
- azadirachtin (neem oil)-Some formulations are OMRI-listed.
- pyrethrins (often combined with other ingredients)-Some formulations are OMRI-listed for organic use.
Management-chemical control: COMMERCIAL USE
- chloropicrin (Telone)-Preplant.
- ethoprop (Mocap 15%) at 0.9 to 1.4 lb product/1,000 row ft. Apply in 12- to 15-inch band on the row. See label for adjustments based on specific row spacing. Do not place in contact with seed. Do not apply within 140 ft of aquatic habitat.