How to Manage Pests

UC Pest Management Guidelines

Citrus

Twospotted Spider Mite

Scientific Name: Tetranychus urticae

(Reviewed 2/17, updated 2/17)

In this Guideline:


Description of the Pest

This species has two dark spots, composed of food content, showing through the transparent body wall. The abdomen is oval and sparsely covered with spines. The adult male is smaller than the female and is characterized by its distinctly pointed abdomen. It sometimes has an orange or brown tinge and is usually more active than the female. The female is more robust than the male and is more oval in shape. Color of the female can vary; typically, it is a pale leaf-green, but it can also be tinged with yellow, brown, and sometimes orange.

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 numbers increase, they can also be found on the upper side of leaves and on fruit. They cover leaves and fruit with 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

As a result of their small size and habit of feeding on the underside of foliage, this species may go undetected until a population has caused serious damage to a tree. 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 roundand spray with the most selective miticide to preserve 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 damage from spider mite feeding.

Organically Acceptable Methods

Use cultural and biological controls and certain petroleum oil sprays (such as PureSpray Green NR 440) on organically managed citrus.

Selectivity

Miticides available for controlling twospotted spider mite in bearing orchards include abamectin (Agri-Mek, etc.), acequinocyl (Kanemite), fenbutatin oxide (Vendex), fenpyroximate (Fujimite), hexythiazox (Onager), oil, propargite (Omite), pyridaben (Nexter), spirodiclofen (Envidor); in nonbearing orchards, bifenazate (Acramite) can be used.

Of these miticides, some are more selective than others. Acequinocyl, bifenazate, fenbutatin oxide, and oil have the least effect of all on natural enemies, including predatory mites, but they also provide a shorter period of control of pest mites. Etoxazole, hexythiazox, propargite, pyridaben, and spirodiclofen are of intermediate selectivity because they harm both pest mites and predatory mites for up to 6 weeks but cause minimal harm to beneficial insects such as lacewings, lady beetles, and Aphytis melinus, which help control caterpillars, scale, thrips, and other pests.

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 numbers of mites in summer and fall may require miticide applications, but thresholds have not been established.

Common name Amount to use REI‡ PHI‡
(Example trade name) (type of coverage)** (hours) (days)
Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
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. Not all registered pesticides are listed. Always read the label of the product being used.
 
NONBEARING TREES ONLY
 
A. BIFENAZATE
  (Acramite 50WS) 0.75–1 lb/acre (OC) 12 1 year
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: un
  COMMENTS: For use in nonbearing orchards only. Do not apply more than once per year. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
BEARING TREES
 
A. NARROW RANGE OIL (92% UR)
  (415, 440) 1.2–1.4% (OC) See label When dry
  . . . or . . .
  NARROW RANGE OIL (99% UR)
  (415, 435, 440, 455) 1.2–1.4% (OC) See label When dry
  RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and mites); Natural enemies: most
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Use highest rate for July or August applications. Narrow range 440 (or higher) spray oil is preferable in the Central Valley during warmer months because of greater persistence, but risk of phytotoxicity increases unless using products with 99% unsulfonated residues (UR). Caution: Serious hazards are associated with oil sprays to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
  . . . or . . .
  NARROW RANGE OIL (92 OR 99% UR)
  (415) 6–20 gal/acre (LV) See label When dry
  RANGE OF ACTIVITY: Pests: narrow (citrus red mite) Natural enemies: predatory mites.
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE OF ACTION: Contact including smothering and barrier effects.
  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 sprays to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
 
B. ACEQUINOCYL
  (Kanemite 15SC) 21–31 oz/acre (OC or IC) 12 7
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 20B
  COMMENTS: For use on oranges, grapefruit, and lemons only. Apply by ground using 100 to 250 gal water/acre. Do not use less than 100 gal water/acre. Allow a minimum of 21 days between applications.
 
C. HEXYTHIAZOX
  (Onager) 12–24 oz/acre (OC or IC) 12 28
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: short to intermediate
  MODE-OF-ACTION GROUP NUMBER1: 10A
  COMMENTS: Do not apply more than once per year. Effective against the egg stage.
 
D. PYRIDABEN
  (Nexter) Label rates (OC or IC) 12 7
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 21A
  COMMENTS: When this pesticide was used during April and May in the San Joaquin Valley and thrips were abundant, there was an increase in scarring damage caused by thrips. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
E. FENPYROXIMATE
  (Fujimite 5EC) 4 pt (OC or IC) 12 14
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 21A
 
F. SPIRODICLOFEN
  (Envidor 2SC) See comments 12 7
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 23
  COMMENTS: Application rate is 12 to 20 fl oz/acre (OC or IC) when horticultural spray oil is not used, and 18 to 20 fl oz/acre (OC or IC) when it is.
 
G. ABAMECTIN*  
  (Agri-Mek 0.15EC) 10–20 fl oz/acre (OC or IC) 12 7
  RANGE OF ACTIVITY: Pests: intermediate (citrus thrips, mites, leafminers); Natural enemies: predatory mites & thrips
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  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.
  . . . PLUS . . .
  NARROW RANGE OIL
  (415) 0.25–1% See label when dry
  RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and mites); Natural enemies: most
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE OF ACTION: Improves translaminar movement and persistence of insecticide.
  COMMENTS: For use on all varieties. Most effective in the spring when the trees are flushing. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2017. Review the Department of Pesticide Regulation's updated fact sheet.
 
H. FENBUTATIN OXIDE*
  (Vendex 50WP) 0.25–0.5 lb/100 gal (OC or IC) 48 7
    . . . or . . .    
    2–4 lb/acre (LV)    
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE-OF-ACTION GROUP NUMBER1: 12B
  COMMENTS: For use on all varieties. Use higher rates during cool weather periods. Do not apply more than 1600 gal dilute spray/acre.
 
I. PROPARGITE
  (Omite 30WS)* 7.5–10.5 lb/acre (OC or IC) See label NA
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  RESISTANCE: Some twospotted spider mite populations.
  MODE-OF-ACTION GROUP NUMBER1: 12C
  COMMENTS: For oranges and grapefruit. Check with county ag. commissioner to determine if there is 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. 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.
 
 
** LV - Low-volume uses 20 to 100 gal water/acre.
  OC - Outside coverage uses 100 to 250 gal water/acre.
  IC - Intermediate coverage uses 250 to 600 gal/acre.
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 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 (un = unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee).

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441

Insects, Mites, and Snails

E. E. Grafton-Cardwell, Lindcove Research and Extension Center, Exeter and Entomology, UC Riverside
J. G. Morse, Entomology, UC Riverside
D. R. Haviland, UC Cooperative Extension, Kern County and UC IPM Program
B. A. Faber, UC Cooperative Extension, Santa Barbara and Ventura counties

Acknowledgments for contributions to Insect, Mite, and Snails:
J. Barcinas, E.S.I., Corona, CA
R. Dunn, Badger Farming Co., Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
C. E. Kallsen, UC Cooperative Extension, Kern County
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
N. V. O'Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
T. Roberts, E.S.I., Corona, CA
T. Shea, UC Cooperative Extension, Riverside County
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA

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