How to Manage Pests

UC Pest Management Guidelines

Citrus

Citrus Red Mite

Scientific Name: Panonychus citri

(Reviewed 2/17, updated 2/17)

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.

Mite numbers 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 numbers feed on nearly mature fruit, the silvering may persist. High numbers 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 numbers than previously thought and pesticides are not normally required in healthy orchards under a biologically based IPM program. Mite numbers tend to be higher in spring and fall, especially in orchards where natural enemies are destroyed by the use of broad-spectrum insecticides such as pyrethroids, organophosphates, carbamates and neonicotinoids. Monitor orchards and use narrow range oils and selective miticides whenever possible.

Biological Control

Predaceous mites, predaceous insects, and a virus are important in regulating citrus red mite numbers. 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.

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 numbers are high and can rapidly reduce them. 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 numbers.

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

Use cultural and biological controls and petroleum oil sprays on organically managed citrus.

Selectivity

Miticides available for controlling citrus red mite (bearing orchards only) include acequinocyl (Kanemite), fenbutatin oxide (Vendex), hexythiazox (Onager), oil, propargite (Omite), pyridaben (Nexter), spirodiclofen (Envidor), and fenpyroximate (Fujimite). For nonbearing orchards only, 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, fenpyroximate, 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 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 numbers are considered to be beneficial as they provide food for natural enemies. High temperatures and virus reduce mite numbers in June and July and no pesticides are generally required during summer.

In orchards where nonselective pesticides have destroyed natural enemies, pesticides may be required in spring to prevent excessive mite numbers 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 pesticide application. However, fall populations, in conjunction with the Santa Ana winds, can be very damaging if nonselective pesticides or dust upset naturally occurring control. In late summer, monitor orchards about every 2 weeks as described above for the San Joaquin Valley. Consider applying a pesticide 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 pesticide applications 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, phytotoxicity risks from oil during mite sprays are less than with a scale application. For additional information, see Managing Insects and Mites with Spray Oils,UC ANR Publication 3347.

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. through Feb. following subfreezing temperatures during the previous week or when subfreezing temperatures are anticipated during the following 2 weeks.
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 (UR 92%)
  (415, 440) 1.2–1.4% (OC or IC) See label When dry
  . . . or . . .
  NARROW RANGE OIL (UR 99%)
  (415, 435, 440, 455) 1.2–1.4% (OC or IC) 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). Low-volume may be preferable. 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: Use highest rate for July or August applications. Low-volume may be preferable. 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.
 
C. CYFLUMETOFEN
  (Nealta) 13.7 fl oz/acre 12 7
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: short
  MODE-OF-ACTION GROUP NUMBER1: 25
  COMMENTS: Do not apply more than 27.4 fl oz/acre. Do not make applications at intervals shorter than 14 days.
 
D. 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
 
E. 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. Prevents egg hatch.
 
F. 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.
 
G. 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.
 
H. SPIROTETRAMAT
  (Movento) 8-10 fl oz/acre (OC) 24 1
  RANGE OF ACTIVITY: Pests: broad (mites, thrips, leafminers, aphids, armored scales); Natural enemies: predatory mites
  PERSISTENCE: Pests: long; Natural enemies: short (except via leaf or host feeding)
  MODE-OF-ACTION GROUP NUMBER1: 23
  . . . PLUS . . .
  NARROW RANGE OIL
  (415) 0.5–1% See label See label
  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 effects; also improves insecticide uptake.
 
I. PROPARGITE
  (Omite 30WS)* 7.5–10.5 lb/acre See label NA
  RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 12C
  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 pesticide does not work well in cool weather.
 
J. 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 pesticide 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.
 
** 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.
NA Not applicable
* 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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