How to Manage Pests
UC Pest Management Guidelines
Scientific Name: Scutigerella immaculata
In this Guideline:
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. Transplants may be
stunted by their feeding as new roots attempt to grow out of the transplant
Symphylan damage is generally associated with soils that are high in
organic matter content with 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; and 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
Numerous organisms prey on symphylans in the field including true
centipedes, predatory mites, predaceous ground
and various fungi; however, little is known about their effect on symphylan
Organically Acceptable Methods
Cultural practices such as packing the soil surface after planting
and flooding are suitable for organic crops.
Monitoring and Treatment Decisions
Sampling for symphylans is difficult and visible detection of any
symphylans often indicates a population large enough to cause economic damage.
A sampling plan modified from one developed by researchers at Oregon State has
proven very efficient and relatively easy. Place thick slices of raw potato on
the soil surface at the level at which moisture is clearly visible in the soil.
Be careful when removing dry soil from the surface not to disturb the pores in
the moist soil to prevent symphylans from reaching the bait. This can be done
by raking the dry soil away with a lettuce knife, rather than slicing into the
soil with a knife or spade. Then cover the bait with a solid plastic dome to
protect the bait from drying out while it is allowed to attract symphylans.
This plastic dome or cap must be large enough not to cause excessive heating of
the area or to accumulate excess condensation. A 6 X 6 inch round white plastic
pot with no drainage holes or a styrofoam cup is adequate. Leave the bait in
place for 24 to 36 hours and then remove the cover to count the symphylans,
both on the potato slice and on the soil surface underneath. Count the soil
surface first as the symphylans there will quickly hide.
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.
|When choosing a pesticide,
consider information relating to natural enemies and honey bees as
well as the environmental impact. Not all registered pesticides are listed. Always read label of product being used.
||MODE OF ACTION GROUP
||COMMENTS: Avoid drift and tailwater runoff into surface waters.
||2.4 fl oz/1000 ft
||MODE OF ACTION GROUP
||COMMENTS: For cabbage. Apply 1 week before planting.
||. . . or . . .
||0.9 lb/1000 ft
||MODE OF ACTION GROUP
||COMMENTS: For cabbage. Apply at planting.
UC IPM Pest Management Guidelines: Cole Crops
UC ANR Publication 3442
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
Acknowledgments for contributions to Insects and Mites:
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
W. E. Chaney, UC Cooperative Extension, Monterey County
N. C. Toscano, Entomology, UC Riverside
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