Description of the Pest
Twospotted spider mite eggs are laid on the undersides of leaves and are spherical, clear, and colorless when laid but become pearly white as hatch approaches. Nymphs, adult males, and reproductive adult females are oval shaped and generally yellow or greenish in color. There are one or more dark spots on each side of their bodies, and the top of the abdomen is free of spots. Adult female twospotted spider mites may cease to reproduce during the coldest winter months in production areas of colder inland valleys. Diapause is indicated by a change in color to bright orange.
Carmine spider mite, a close relative of the twospotted spider mite, is bright red in color. It is commonly found at low densities in southern California and San Joaquin Valley growing regions. Populations usually decline as temperatures warm in spring.
Spider mites can cause leaves to yellow and eventually die and drop from the plant. Loss of leaf surface reduces energy available to maturing fruit. Entire plants in heavily infested areas of the field may be defoliated. These mites also produce webbing on plants where they feed. Damage frequently occurs in 'hot spots' such as areas of the field near dusty roads.
Monitor fields weekly from June through August. Look for plants with yellowish leaves or defoliated plants. Examine plant leaves for webbing, especially on older leaves in the middle of the plant with symptoms. For spring-planted fields that are pruned in early July, treat after pruning for better coverage.
Predaceous mites are not as effective in controlling pest mites in crops such as eggplant with hairy leaves.
|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.|
|(Agri-Mek SC)*||1.75-3.5 fl oz||12||7|
|MODE-OF-ACTION GROUP NUMBER1: 6|
|COMMENTS: Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. Certain abamectin formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations of abamectin.|
|(Vendex 50WP)*||2–3 lb||48||3|
|MODE-OF-ACTION GROUP NUMBER1: 12B|
|(Oberon 2SC)||7–8.5 fl oz||12||1|
|MODE-OF-ACTION GROUP NUMBER1: 23|
|D.||NARROW RANGE OIL#|
|MODE OF ACTION: Contact including smothering and barrier effect.|
|COMMENTS: Requires repeat applications. Check with certifier to determine which products are organically acceptable.|
|**||See label for dilution rates.|
|‡||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.|
|#||Acceptable for use on organically grown produce.|
|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).|