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UC Pest Management Guidelines


Foliage damaged by twospotted spider mites.

Eggplant

Webspinning Spider Mites

Scientific Names: Carmine mite: Tetranychus cinnabarinus
Twospotted spider mite: Tetranychus urticae

(Reviewed 4/10, updated 4/10)

In this Guideline:


DESCRIPTION OF THE PESTS

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.

DAMAGE

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.

MANAGEMENT

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.

Biological control
Predaceous mites are not as effective in controlling pest mites in crops such as eggplant with hairy leaves.

Common name Amount/Acre** 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. ABAMECTIN*
  (Agri-Mek) 0.15EC 8-16 fl oz 12 7
  MODE OF ACTION GROUP NUMBER1: 6
   
B. FENBUTATIN OXIDE*
  (Vendex) 50WP 2–3 lb 48 3
  MODE OF ACTION GROUP NUMBER1: 12B
 
C. NARROW RANGE OIL# Label rates 4 0
  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 (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.
* 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). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Eggplant
UC ANR Publication 3475
Insects and Mites
R. H. Molinar, UC Cooperative Extension Fresno County
J. L. Aguiar, UC Cooperative Extension Riverside County
M. J. Jimenez, UC Cooperative Extension Tulare County
P. B. Goodell, UC IPM, Kearney Agricultural Center, Parlier

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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