How to Manage Pests

UC Pest Management Guidelines

Citrus

Citrus Red Mite

Scientific Name: Panonychus citri

(Reviewed 9/08, updated 9/08, corrected 6/13)

In this Guideline:


Description of the Pest

Adult female citrus red mites are oval and globular; the male is smaller and has a tapered abdomen. Each female lays 20 to 50 eggs at a rate of 2 to 3 a day, depositing them on both sides of leaves. The life cycle from egg to egg may be as short as 12 days during warm weather.

Populations increase in spring, late summer, and early fall in response to new growth; citrus red mites prefer to feed on fully expanded young leaves but will also infest fruit.

Damage

On leaves, citrus red mite feeding results in a pale stippling visible primarily on the upper surface of the leaf. In severe infestations, the stippling enlarges to dry necrotic areas (commonly called mesophyll collapse). Eventually, leaves may drop and twigs dieback. Stippling or silvering also occurs on green fruit but usually disappears when fruit change color. If large populations feed on nearly mature fruit, the silvering may persist. High populations can also cause fruit sunburn if hot weather is occurring. During fall Santa Ana winds, low levels of citrus red mite can cause a blasting or burning of foliage and leaf drop in coastal and southern California growing areas.

Management

Citrus red mite is more of a problem when trees are water stressed and conditions are hot and dry. Research on San Joaquin Valley navels and coastal lemons showed citrus can tolerate much higher populations than previously thought and treatment is not normally required in healthy orchards under a biologically based IPM program. Populations tend to be heavier in spring and fall, especially in orchards where natural enemies are destroyed by the use of broad-spectrum insecticides such as formetanate hydrochloride (Carzol) or methidathion (Supracide). Monitor orchards and use narrow range selective miticides whenever possible.

Biological Control

Predaceous mites, predaceous insects, and a virus are important in regulating citrus red mite populations. The most important natural enemy is the predaceous mite (Euseius tularensis). These beneficial mites can establish their populations before citrus red mites are numerous because they have alternate food sources (pollen, citrus thrips larvae, leaf sap, nectar, and honeydew). They mainly attack immature stages of the citrus red mite. The female of both species is about the same size as the female citrus red mite but is pear-shaped, shiny, and translucent. Predator eggs are clear, oval, and about twice the size of citrus red mite eggs. Eggs hatch and develop into adults in about 8 days.

Other predators of the citrus red mite include a small black lady beetle (Stethorus picipes), a predaceous dustywing (Conwentzia barretti), and the sixspotted thrips (Scolothrips sexmaculatus). In addition, a disease caused by a virus specific to citrus red mite is widespread in citrus-growing areas. The disease becomes epidemic under warm, moderately dry conditions when mite populations are high and can rapidly reduce the mite population. Symptoms of virus-infected mites include stiff movements, legs curled under the body, and subsequent disintegration of the body. If diseased mites are mounted on a slide and examined under a polarizing microscope, internal crystals that shine in the polarized light are evident.

Besides predators and the virus, hot temperatures (above 90°F) and low humidity also reduce citrus red mite populations.

Cultural Control

Mites increase their reproduction on water-stressed trees. Good irrigation reduces red mite outbreaks. Water roads to limit dust buildup, which also promotes mites.

Organically Acceptable Methods

Cultural and biological controls and petroleum oil sprays are acceptable on organically managed citrus.

Selectivity

Miticides available for controlling citrus red mite (bearing orchards only) include acequinocyl (Kanemite), dicofol (Dicofol), fenbutatin oxide (Vendex), hexythiazox (Onager), oil, propargite (Omite), pyridaben (Nexter), and spirodiclofen (Envidor). For nonbearing orchards only, bifenazate (Acramite) and etoxazole (Zeal) 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. Dicofol, etoxazole, hexythiazox, propargite, pyridaben, and spirodiclofen are of intermediate selectivity because they impact both pest mites and predatory mites for up to 6 weeks but have minimal impact on beneficial insects such as lacewings, lady beetles, and Aphytis melinus, which help control caterpillars, scale, thrips, and other pests.

Monitoring and Treatment Decisions

In February in the San Joaquin Valley, survey each orchard to determine if mites are present. Scan several leaves per tree at various sites, and use a hand lens to check a few leaves for eggs and immatures. In southern California and coastal areas, depending on the local situation, consider monitoring beginning in late summer.

Monitoring in the San Joaquin Valley

In March, or as soon as mites are detectible, begin monitoring by collecting a total of 100 fully expanded leaves from throughout the orchard. Select leaves from just inside the shady region of the tree. Using this sample:

  • Determine the average number of pest mites per leaf by dividing the total number of mites found by 100.
  • Count the number of active stages of predatory mites and calculate the average number of predatory mites by dividing the total number of predatory mites by 100.
  • Note the presence of virus-infected citrus red mites.
  • Repeat this sampling about every 2 weeks until red mite numbers decline below 1 per leaf and petal fall has occurred. Keep records of your monitoring results (example formPDF).

In San Joaquin Valley navel oranges, economic loss will not occur if citrus red mite densities do not exceed eight mature females per leaf by 2 to 4 weeks after petal fall. Vigorous, well-irrigated trees can tolerate more. Low-to-moderate populations are considered to be beneficial as they provide food for natural enemies. High temperatures and virus reduce mite populations in June and July and no treatment is generally required during summer.

In orchards where nonselective pesticides have destroyed natural enemies, treatments may be required in spring to prevent excessive mite populations at petal fall. Use the application times listed in the following table when applying oil sprays.

Monitoring in Southern California and Coastal Areas

Spring and summer populations of citrus red mite generally do not require regular monitoring or treatment. Fall populations can be very damaging in conjunction with the Santa Ana winds if naturally occurring control is upset by nonselective pesticides or dust. About every 2 weeks in late summer, monitor orchards as described above for the San Joaquin Valley. Consider applying a treatment before Santa Ana conditions if there are more than eight to ten citrus red mites per leaf.

In southern California and coastal areas, spring and summer populations of citrus red mite do not require treatment, but fall populations can be very damaging in conjunction with the Santa Ana winds if naturally occurring control is upset by nonselective pesticides or dust. Begin monitoring orchards in late summer, and consider applying a treatment before Santa Ana conditions if there are more than eight to ten citrus red mites per leaf.

Use of Oils

Extensive research on the use of oil sprays against various mite and scale insects has resulted in the development of recommendations that use specific rates and timing of treatments on different varieties of citrus in different regions of California in order to achieve expected pest control and limit the potential for leaf or fruit drop or fruit damage as a result of phytotoxicity. The narrow range 415, 440, and 455 oils were specifically developed for use in California to limit these concerns. Precautions for using petroleum spray oils are listed at the beginning of this guideline. Because mites are on the outside of the tree and sprayed with outside coverage, risks of phytotoxicity from oil are less than with a scale application. For additional information, see Managing Insects and Mites with Spray Oils.

Type of oil
(coverage)**
Varieties Application times to avoid tree injury
Central areas Southern areas
NR 415 (IC, OC) Grapefruit July–Sept. Aug.–Oct.
  Lemons Aug.–Sept. Coastal: Apr.–June and/or Sept.–Dec.
      Interior: Apr.–May and/or Sept.–Nov.
  Navels July–Sept.1 Aug.–Sep.1
  Valencias July–Sept.1 Aug.–Oct.1
NR 415 (LV) Grapefruit Mar.–Nov.2 Mar.–Nov2
  Lemons Mar.–Nov. or 21 days before picking2 Mar.–Nov.2
  Navels Aug. 15–Sept. and as needed during prebloom1 Sept.–Oct.1
  Valencias Mar.–Nov.1,2 Mar.–Nov.1, 2
NR 440 and 455 (IC, OC) Grapefruit Aug.–Sept. Aug.–Oct.
  Lemons Aug.–Sept. Coastal: May–June and/or Sept.–Dec.
      Interior: Apr.–May and/or Sept.–Nov.
  Navels July–Aug.1 Aug.1
  Valencia July–Aug.1 Aug.1
** LV – Low volume uses 20 to 100 gal water per acre. Do not use when temperatures will exceed 95°F (85° to 90°F on coast).
  OC – Thorough coverage uses 100 to 250 gal water per acre, depending on tree size.
  IC – Intermediate coverage uses 250 to 600 gal water per acre.
1 Treatment can also be made from Feb. 15 - 50% bloom, but to avoid tree injury at this time, use only the low concentration (1.2%).
2 Do not apply Dec.-Feb. following subfreezing temperatures during the previous week or when subfreezing temperatures are anticipated during the following 2 weeks.
Common name Amount to use R.E.I.‡ P.H.I.‡
(example trade name) (type of coverage)** (hours) (days)

  Calculate impact of pesticide on air quality
 
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of 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: unknown
  COMMENTS: For use in nonbearing orchards only. Do not apply more than once per year.
 
B. ETOXAZOLE
  (Zeal) 2–3 oz/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: 10B
  COMMENTS: For use in nonbearing orchards only. Do not apply more than once per year.
 

BEARING TREES

 
A. NARROW RANGE OIL (UR 92%)
  (415, 440) 1.2–1.4% (OC or IC) 4 When dry
  . . . or . . .
  NARROW RANGE OIL (UR 99%)
  (415, 435, 440, 455) 1.2–1.4% (OC or IC) 4 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). Low-volume 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 . . .
  NARROW RANGE OIL (92 or 99% UR)
  (415) 6–20 gal/acre (LV) 4 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: Use highest rate for July or August applications. Low-volume may be preferable. Caution: Serious hazards are associated with oil treatments 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 100-250 gal water/acre. Do not use less than 100 gal water/acre.
 
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.
 
D. PYRIDABEN
  (Nexter) WSB 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 material 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.
 
E. FENPROXIMATE
  (Fujimite) 5EC 1–4 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. PROPARGITE
  (Omite) CR 7.5–10 lb/acre (OC or IC) 42 days 365
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE OF ACTION GROUP NUMBER1: 12C
  COMMENTS: For use on oranges and grapefruit. Do not apply within 40 days of an oil application, but oil may be applied 30 days or more after propargite. This material does not work well in cool weather.
  . . . or . . .
  (Omite)* 30W
  COMMENTS: For oranges and grapefruit. Check with county ag. commissioner to determine if there is a current 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. This material does not work well in cool weather.
 
G. FENBUTATIN OXIDE*
  (Vendex) 50WP 0.24–0.5 lb/100 gal (OC or IC) 48 7
    . . . or . . .
    3 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. This material does not work well in cool weather and requires higher rates during these periods. Do not apply more than 1,600 gal dilute spray per acre.
 
H. 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 horticultural spray oil is used.
 
I. DICOFOL
  (Dicofol) 4E 0.8 pt/100 gal (OC or IC) 12 7
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  RESISTANCE: in some citrus red mite populations.
  MODE OF ACTION: unknown
  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.
 
** LV - Low-volume uses 20–100 gal water/acre.
  OC - Outside coverage uses 100–250 gal water/acre.
  IC - Intermediate coverage uses 250–600 gal/acre.
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.
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). For additional information, see their Web site at http://www.irac-online.org/.

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, Entomology, UC Riverside and Kearney Agricultural Center, Parlier
  • J. G. Morse, Entomology, UC Riverside
  • N. V. O'Connell, UC Cooperative Extension, Tulare County
  • P. A. Phillips (emeritus), UC IPM Program, UC Cooperative Extension, Ventura County
  • C. E. Kallsen, UC Cooperative Extension, Kern County
  • D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgments for contributions to Insect, Mites, and Snails:
  • 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
  • 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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