How to Manage Pests
UC Pest Management Guidelines
Garden symphylans (also called garden centipedes) are not insects; they are in their own arthropod class Symphyla. When full grown they are not more than 0.5 inch long and have 15 body segments and 11 to 12 pairs of legs. They are slender, elongated, and white with prominent antennae.
Symphylans may damage sprouting seeds, seedlings before or after emergence, or older plants. They feed primarily on root hairs and rootlets, and their ability to injure the crop decreases as plants get larger. However, their pitting of older roots may provide entryways for pathogens.
Symphylan damage is generally associated with soils that are high in organic matter content and have good soil structure. Symphylans do not thrive in either compact soil 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.
Flooding has been used to control symphylans in some situations but has been unsuccessful in others. Flooding requires at least 2 to 3 weeks, is more likely to be effective in late spring or summer than in winter, and is probably most effective where there is a high water table. Symphylans may be found more than 3 feet below the soil surface and flooding to this level in many soils is difficult. Even in the best circumstances, flooding will only reduce populations; they can be expected to increase when conditions are again favorable. Effectiveness of rotations with nonhost crops has not been studied. Soil fumigation can kill populations in the upper soil levels; eventually, however, the soil will be reinfested by populations deeper in the soil.
Organically Acceptable Methods
and Treatment Decisions
If symphylan counts approach 75 per potato slice, complete stand loss may occur. Significant stand loss will occur at lower symphylan populations.
Infested soil can be treated with insecticides, but their effect is limited because of the symphylan's ability to migrate deep into the soil. Insecticides may help in giving the plants a chance to establish in a protected zone. Treat for symphylans just before planting. Spot treatments may be adequate.
UC IPM Pest Management Guidelines: Spinach