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UC Pest Management Guidelines


Garden symphylan.

Dry Beans

Garden Symphylans

Scientific names:
Scutigerella immaculata

(Reviewed 12/08, updated 12/08)

In this Guideline:


DESCRIPTION OF THE PESTS

Garden symphylans, also called garden centipedes, are slender, white arthropods, closely related to insects, about 0.33 inch (8 mm long), with 10 to 12 prolegs and distinct antennae. These fast-moving arthropods live in soil and move up and down in the soil profile in relation to the moisture gradient. After an irrigation they are near the soil surface. As the soil dries, they move deeper. They hide when exposed to light. They occur mainly in soil with high organic matter and especially in organic farms that fertilize with manures. Symphylans are long lived; some adults may live several years. They move long distances in the soil profile (up to 3 feet below the soil surface), yet cannot tunnel through soil but must rely on existing soil pores. They do not thrive in either compact soil or sandy soils because these soils do not provide them with adequate tunnels for their movement.

DAMAGE

Garden symphylans feed on decaying as well as living plant material. They may damage seedlings (before or after emergence) or older plants. They slow growth by feeding on root hairs and small roots and feeding damage on older roots may provide entryways for pathogens. Damage usually is concentrated in relatively small areas and recurs every season; infestations spread slowly.

MANAGEMENT

This pest usually occurs in relatively small areas and in soils with a high organic matter. Reduce organic content and monitor known trouble spots to determine the need for spot treatments.

Cultural Control
Reduce the amount of undecomposed plant material or manure that is applied to the soil. Wait to seed until soil-incorporated weeds or manure has been broken down. Planting a higher seed population in problem areas may help compensate for damage.

Organically Acceptable Methods
Cultural control is an organically acceptable management tool.

Monitoring and Treatment Decisions
Research from other areas of the country indicates that symphylans can be detected with bait trapping. Either carrots or potatoes can be used as bait. Cut the bait in half longitudinally and scratch the cut surface just before placing it on the soil to ensure that the surface is moist. Place the bait at a depth where the soil is moist, and cover it with a plastic cup to exclude light and prevent the soil from drying. Use at least a dozen bait traps in the field. After 2 to 5 days, examine the cut surface and the soil upon which it was resting for evidence of symphylans. If they are detected, consider a treatment. If large numbers are detected (more than 20 per bait station), consider planting the field to a different crop.

Infested soil can be treated with an insecticide, but its 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.

Common name Amount/Acre** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. LAMBDA-CYHALOTHRIN*
  (Warrior with Zeon) 3.2 fl oz 24 see comments
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: PHI is 7 days for succulent shelled or edible podded crops and 21 days for dried shelled crops.
     
B. CYFLUTHRIN*
  (Baythroid) Label rates 12 7
  (Renounce) 20WP Label rates 12 7
  MODE OF ACTION GROUP NUMBER1: 3
 
** See label for dilution rates.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment until harvest can take place. In some cases the R.E.I. exceeds the P.H.I. The longer of these two intervals is the minimum time that must elapse before harvest may take place.
* Permit required from county agricultural commissioner for purchase or use.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Dry Beans
UC ANR Publication 3446
Insects and Mites
L. D. Godfrey, Entomology, UC Davis
R. F. Long, UC Cooperative Extension, Yolo County

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