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UC Pest Management Guidelines


Adult twospotted spider mite, Tetranychus urticae.

Fig

Webspinning Spider Mites

Scientific Names:
Pacific spider mite: Tetranychus pacificus
Twospotted spider mite: Tetranychus urticae

(Reviewed 7/06, updated 1/09)

In this Guideline:


DESCRIPTION OF THE PESTS

The twospotted spider mite is most common in the Sacramento Valley and the Pacific spider mite in the San Joaquin Valley. Both species produce abundant webbing on both sides of the leaves. The two mites are not easily distinguished. Both have two black spots on their yellow green bodies. In fall they turn orange red. The twospotted spider mite and Pacific spider mite overwinter as adult females under bark and in weeds. When weeds dry in spring, the mites move to trees and feed on lower leaves first. There are many overlapping generations each summer, with eggs being laid on the underleaf surface.

DAMAGE

Spider mites feed by sucking the contents out of leaf cells. Such leaf damage reduces tree vitality. Most feeding takes place on the underside of leaves. Heavy feeding causes browning of leaves and defoliation.

MANAGEMENT

Vigorously growing trees are much more tolerant to mite attack than trees under stress. Maintain trees with optimum irrigation and fertilization. Reducing dust not only reduces spider mite populations but also may limit Alternaria rot disease.

Predaceous mites, Metaseiulus spp., and the sixspotted thrips, Scolothrips sexmaculatus, feed heavily on webspinning mites and may give complete control in the orchard. The western flower thrips, Frankliniella occidentalis, feeds on mite eggs and may prevent a mite population from increasing.

No economic threshold levels have been established for spider mites on figs. Apply treatments before leaf damage becomes severe and defoliation from mite damage ensues.

Common name Amount to Use R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to impact on natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. NARROW RANGE OIL#
  (Omni Supreme Spray) 1.5–2 gal/100 gal water 4 0
  MODE OF ACTION: Contact including smothering and barrier effects.
 
B. BIFENAZATE
  (Acramite) 50WS 0.75–1 lb/acre 12 365
  MODE OF ACTION GROUP NUMBER1: 25
  COMMENTS: For use on nonbearing figs only. Do not apply more than 1 application/year
 
+ 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 to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
# 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). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Fig
UC ANR Publication 3447
Insects and Mites
R. L. Coviello, UC UC Cooperative Extension, Fresno County
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier

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