How to Manage Pests

UC Pest Management Guidelines

Citrus

Yuma Spider Mite

Scientific Name: Eotetranychus yumensis

(Reviewed 2/17, updated 2/17)

In this Guideline:


Description of the Pest

Yuma spider mite, is a sporadic pest of citrus in the inland valleys of California. It is similar in shape to the citrus red mite but is light straw to dark pink colored and is much more shiny in appearance. It lays spherical, peach-colored eggs within substantial amounts of webbing on the underside of leaves and sometimes fruit.

In the Coachella and Imperial valleys, Yuma spider mite occurs on grapefruit and lemons and is most numerous in winter and late spring. In the southern San Joaquin Valley, it is primarily found on mandarins during summer.

Damage

Yuma spider mite feeds by using its mouthparts to pierce and drink fluids from plant cells. Feeding on leaves causes discoloration and in severe cases defoliation. Feeding on the surface of green fruit causes a stippled and bleached appearance, though in all but severe cases the fruit colors up normally.

Management

Generally damage from Yuma spider mites is not severe enough to warrant a pesticide application. In severe situations it can be controlled with sulfur, oil, or other miticides.

Biological Control

Sixspotted thrips, Scolothrips sexmaculatus, is an effective predator of Yuma spider mite. Other general predators of citrus red mite, such as the spider mite destroyer (Stethorus picipes), minute pirate bugs (Orius spp.), and a predatory mite (Euseius tularensis) also likely play a role in suppression of Yuma spider mite.

Cultural Control

Adequate irrigation and dust control will reduce the damage caused by Yuma spider mite.

Organically Acceptable Methods

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

Monitoring and Treatment Decisions

In mandarins grown in the San Joaquin Valley, check for Yuma spider mite during July and August. Look for stippling of leaves and fruit that is associated with large amounts of webbing. On bearing trees, apply an insecticide if fruit stippling is sufficient to inhibit proper fruit coloring and natural enemies are not already reducing mite densities. On young trees, spray trees if leaf drop appears imminent.

In the Coachella and Imperial valleys, treat if needed to prevent leaf drop. Yuma spider mite can be controlled with sulfur during the period between October and March 15, or with miticides during the remainder of the year.

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. 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.
 
B. 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.
 
C. 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.
 
D. FENPYROXIMATE
  (Fujimite XLO) 2–4 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. 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.
 
F. WETTABLE SULFUR# Label rates (OC or IC) 24 0
  RANGE OF ACTIVITY: Pests: narrow (mites and citrus thrips); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE OF ACTION: unknown
  COMMENTS: For use on all varieties. Apply from Nov. through May when monitoring indicates a need. Do not apply more than 6 lb per 100 gal water. Do not apply during or preceding high temperatures. Do not apply sulfur within two months of a previous oil spray, and do not apply oil 60 to 90 days after a sulfur application. Not recommended for use in the San Joaquin Valley.
 
G. 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
  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. This pesticide does not work well in cool weather.
 
H. FENBUTATIN OXIDE*
  (Vendex 50WP) 0.24–0.5 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. 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/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.
* 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 (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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