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How to Manage Pests

UC Pest Management Guidelines


Twospotted spider mites range from yellow to green.

Citrus

Twospotted Spider Mite

Scientific Name: Tetranychus urticae

(Reviewed 7/03, updated 7/05)

In this Guideline:


DESCRIPTION OF THE PEST
All stages of the twospotted spider mite overwinter in protected places on the tree, such as the navel of navel oranges, under the button, and where fruit touch. If the weather is mild, mites continue to feed and reproduce during winter. Activity increases in late spring and peaks in summer. Spider mites first appear on the underside of leaves and when heavy populations build up, also on the upperside of leaves and on fruit. They cover leaves and fruit with a conspicuous webbing.

Eggs are spherical and translucent when first laid, becoming opaque before hatching. Immature mites molt three times before becoming adults; under ideal conditions, a generation can be completed in 7 days.

DAMAGE
Light infestations result in yellow or brown spots between leaf veins. Clusters of dried, brown leaves and profuse webbing indicate a heavy infestation, which if compounded by water stress, could result in leaf and fruit drop.

MANAGEMENT
The twospotted spider mite is an occasional pest on citrus, particularly in the San Joaquin Valley. Its damage potential varies from year to year and is related to water stress and heat. Monitor for twospotted spider mite year round and treat with the most selective miticide to preserve populations of natural enemies.

Biological Control
A number of predators provide substantial control of twospotted spider mites. These include the sixspotted thrips, Scolothrips sexmaculatus, the spider mite destroyer, Stethorus picipes, minute pirate bugs, Orius spp., and the beneficial mite, Euseius tularensis.

Cultural Control
Adequate irrigation will reduce the impact of spider mite feeding.

Organically Acceptable Methods
Cultural and biological controls and petroleum oil sprays are organically acceptable methods.

Selectivity
Miticides available for controlling twospotted spider mite include dicofol (Kelthane), propargite (Omite), fenbutatin oxide (Vendex), and oil; of these miticides, some are more selective than others. Dicofol and pyridaben are of intermediate selectivity because they act primarily against mites with minimal impact on beneficial insects such as lacewings, lady beetles, and Aphytis melinus, which help control worms, scale, thrips, and other pests. However, these materials are toxic to beneficial mites such as Euseius tularensis. Propargite is even more selective than dicofol because, when used at low rates, it is relatively nontoxic to beneficial mites. Petroleum oil sprays are relatively nontoxic to insect natural enemies but suppress Eusieus tularensis. Fenbutatin oxide has the least effect of all on natural enemies.

Monitoring and Treatment Decisions
In the San Joaquin Valley, check for twospotted mites when you monitor citrus red mite in late winter and early spring. Continue monitoring twospotted mite occasionally during summer and more closely in late summer and fall. Look for yellow-brown spots on foliage, particularly in the last growth flush, indicating feeding by twospotted spider mites. High populations in summer and fall may require treatments, but thresholds have not been established.

Common name Amount to Use Minimum Days before Harvest+
(trade name) (type of coverage)**

A. NARROW RANGE OIL#    
  (415) 1.2–1.4 gal/100 gal (TDC) 4 hours
  RANGE OF ACTIVITY: Broad (unprotected stages of insects and mites)
  PERSISTENCE: Short
  COMMENTS: Use highest rate for July or August applications. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
    ...or...  
    6–20 gal/acre (LV) 4 hours
  RANGE OF ACTIVITY: Narrow (citrus red mite)
  PERSISTENCE: Short
  COMMENTS: Higher amounts of oil are for larger trees or for warmer times of the year to increase persistence. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
  ...OR...
  NARROW RANGE OIL#    
  (440) 1.2–1.4 gal/100 gal (TDC) 4 hours
  RANGE OF ACTIVITY: Broad (unprotected stages of insects and mites)
  PERSISTENCE: Short
  COMMENTS: Use highest rates for July or Aug. application. Low-volume application may be preferable. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
    ...or...  
    6–20 gal/acre (LV) 4 hours
  RANGE OF ACTIVITY: Narrow (citrus red mite)
  PERSISTENCE: Short
  COMMENTS: Higher amounts of oil are for larger trees or for warmer times of the year to increase persistence. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
       
B. FENBUTATIN OXIDE*    
  (Vendex) 50WP 0.25–0.5 lb/100 gal (TDC) 7
    ...or...  
    3 lb/acre (LV)  
  RANGE OF ACTIVITY: Narrow (pest mites)
  PERSISTENCE: Short
  COMMENTS: For use on all varieties. Use higher rates during cool weather periods. Do not apply more than 1600 gal dilute spray/acre or use more than 6 lb/acre/season.
       
C. ABAMECTIN*    
  (Agri-Mek) 10 oz/acre (OC)  
  ŸPLUSŸ    
  NARROW RANGE OIL 0.2–0.5%  
  RANGE OF ACTIVITY: Narrow (citrus thrips, pest mites, beneficial mites)
  PERSISTENCE: Short
  COMMENTS: For use on all varieties. Most effective in the spring when the trees are flushing.
   
D. PROPARGITE    
  RANGE OF ACTIVITY: Narrow (pest mites)
  PERSISTENCE: Intermediate
  RESISTANCE: In some twospotted spider mite populations.
  (Omite) CR 10 lb/acre (TDC) 28
  COMMENTS: For use on oranges, grapefruit, lemons. Do not apply within 40 days of an oil application, but oil may be applied 30 days or more after propargite. Do not apply to resistant mites.
  ...OR...
  (Omite)* 30W 7.5–10 lb/acre (TDC) 28
  COMMENTS: For oranges and grapefruit. Allowed under a Special Local Needs permit for southern California areas. Apply from Oct. 1 to petal fall. Ground application only. Be sure temperatures are below 95°F. No more than 2 applications/fruit year at least 21 days apart. Do not apply within 40 days of an oil application, but oil may be applied 30 days or more after propargite. Do not apply to resistant mites.
         
E. DICOFOL    
  (Kelthane MF) 4E 0.8 pt/100 gal (TDC) 7
  RANGE OF ACTIVITY: Narrow (pest and beneficial mites)
  PERSISTENCE: Long
  RESISTANCE: In some twospotted spider mite populations.
  COMMENTS: For use on all varieties. Use on nonresistant mites only; resistance has been reported in the San Joaquin Valley. Closed application system required with this material. Can cause secondary outbreaks of citrus red mites. Do not exceed 6 pt/acre.
   
** OC – Outside coverage uses 50–500 gal water/acre.
  TDC - Thorough distribution coverage uses 500–3,000 gal water/acre, but less than thorough coverage (TC).
+ LV - Low-volume uses 20–100 gal water/acre.
  Minimum days before harvest takes into account the California restricted entry interval and the federal preharvest interval and lists the longer interval. (See Table 1 Mandatory Intervals Between Application, Reentry and Harvest, and Hazards to Bees.)
* Permit required from county agricultural commissioner for purchase or use.
# Acceptable for use on organically grown produce.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Insects, Mites, and Snails
E. E. Grafton-Cardwell, Kearney Agricultural Center, Parlier
J. G. Morse, Entomology, UC Riverside
N. V. O’Connell, UC Cooperative Extension, Tulare Co.
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura Co.
C. E. Kallsen, UC Cooperative Extension, Kern Co.
D. R. Haviland, UC Cooperative Extension, Kern Co.
Acknowledgments for contributions to the insect, mite, and snail section:
J. Barcinas, E. S. I., Corona, CA
R. Dunn, Badger Farming Co., Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
H. Griffiths, E. S. I., Corona, CA
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
T. Roberts, E. S. I., Corona, CA
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA

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