Description of the Pest
Garden symphylans are slender and white, they have 10 to 12 pairs of legs and a pair of antennae. They run rapidly when exposed to light. They occur mainly in moist soils with good structure and a high organic matter content and are often associated with debris from a previous crop that is not completely decomposed. They retreat to deeper soil levels during fallow periods and return to the root zone after crops are planted.
Damage
Garden symphylans damage plants by feeding on roots, thus retarding plant growth. They damage the same area every season, so infestations spread slowly and are usually only a problem in fields that were not fumigated or if the fumigation was ineffective.
Management
Soil fumigation for pathogen and weed seed control will kill symphylans. In nonfumigated fields and fields with large amounts of crop residue from the previous crop, continuous flooding for 3 weeks in the summer helps to reduce infestations and discing in a crop of sorghum has been reported to reduce infestations in other crops. In organic fields, however, the best strategy is to avoid fields that have symphylans in the soil.
Research from other areas of the country indicates that symphylans can be detected with bait trapping. Either carrots or potatoes can be used as the bait. Cut the bait in half longitudinally and scratch the cut surface just before placing it in a shallow hole on the soil to ensure that the surface is moist. (Be sure that when the hole is created, the soil pores or spaces aren't sealed closed. Symphylans use these spaces to travel to the bait.) Cover the bait with a pot. 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 an insecticide application. Because the recommended treatment is best applied before transplanting, bait traps for symphylans a few weeks before transplanting.
| Common name | Amount per acre | REI‡ | PHI‡ | |
|---|---|---|---|---|
| (Example trade name) | (hours) | (days) | ||
| Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used. | ||||
| A. | DIAZINON* | |||
| (Diazinon AG 500) | 1 qt | 72 (3 days) | 5 | |
| (Diazinon 50W) | 2 lb | 72 (3 days) | 5 | |
| MODE-OF-ACTION GROUP NUMBER1: 1B | ||||
| COMMENTS: Broadcast before transplanting and incorporate into top 4 inches of soil. Application after transplanting is less effective, and diazinon must be well watered into the soil. Do not allow this product to run off into surface waters. Highly toxic to bees. | ||||
| ‡ | Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. |
| * | Permit required from county agricultural commissioner for purchase or use. |
| 1 | Rotate insecticides 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; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B. Mode-of-action group numbers for insecticides and miticides (un=unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). |