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How to Manage Pests

UC Pest Management Guidelines

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Citrus

Yuma Spider Mite

Scientific Name: Eotetranychus yumensis

(Reviewed 9/08, updated 9/08)

In this Guideline:

Description of the pest
Damage
Management

Important links
Publication
Glossary

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 treatment. 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 impact of Yuma spider mite.

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

Monitoring and Treatment Decisions
In the San Joaquin Valley, check for Yuma spider mite in mandarins during July and August. Look for stippling of leaves and fruit that is associated with large amounts of webbing. On bearing trees, treat if fruit stippling is sufficient to inhibit proper fruit coloring and beneficial organisms are not already reducing mite densities. On young trees treat if leaf drop appears eminent.

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.

Summary of Important Links

Common name		Amount to Use	R.E.I.+	P.H.I.+
(trade name)		(type of coverage)**	(hours)	(days)

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) 50 WS	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: 25
	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.	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. Do not apply more than 62 oz/acre/season. 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: 10B
	COMMENTS: Do not apply more than once per year.

C.	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: 21
	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. Do not apply more than twice/year.

D.	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: 21
	COMMENTS: Do not make more than 2 applications/season and allow 14 days between applications. Use allowed under a Supplemental Label.

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: Make no more than 1 application/crop season. Application rate is 12-20 fl oz/acre (OC or IC) when horticultural spray oil is not used, and 18-20 fl oz/acre (OC or IC) when it is.

F.	WETTABLE SULFUR#	60 lb/acre (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: Not available.
	COMMENTS: For use on all varieties. Apply from Nov. thru May when monitoring indicates a need. Do not apply more than 6 lb/100 gal water. Do not apply during or preceding high temperatures. Do not apply sulfur within 2 months of a previous oil spray, and do not apply oil 60–90 days after a sulfur treatment. Not recommended for use in the San Joaquin Valley.

G.	PROPARGITE
	(Omite) CR	7.5–10 lb/acre (OC or IC)	42 days	28
	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, grapefruit, lemons. 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	10–15 lb/acre (OC or IC)	42 days	28
	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. 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. This material 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...
		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/acre or use more than 4 lb/acre/season.

I.	DICOFOL
	(Kelthane MF) 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
	MODE OF ACTION: UNC
	COMMENTS: For use on all varieties. Closed application system required with this material. Can cause secondary outbreaks of citrus red mites. Do not exceed 6 pt/acre.

**	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.
#	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 are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

IMPORTANT LINKS

PUBLICATION

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 County
P. A. Phillips, 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 County, 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
K. Godfrey, USDA Biological Control, Sacramento
D. Headrick, California Polytechnic State University, San Luis Obispo
B. Faber, UC Cooperative Extension, Ventura County
J. Kabashima, UC Cooperative Extension, South Coast Research and Extension Center

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