How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

This pest is known as the rust mite on oranges and the silver mite on lemons. It is an occasional pest in coastal areas of southern California and is a problem in some years in inland southern California growing areas. Citrus rust mite is about the same size as a bud mite and requires a hand lens to view; it is deeper yellow in color than the bud mite and wedge shaped. A generation may be completed in 1 to 2 weeks in summer, but development slows or stops in winter, depending on temperature.

DAMAGE

The rust mite feeds on the outside exposed surface of fruit that is 0.5 inch (1.3 cm) or larger. Feeding destroys rind cells and the surface becomes silvery on lemons, rust brown on mature oranges, or black on green oranges. Rust mite damage is similar to broad mite damage, except that somewhat larger fruit are affected. Most rust mite damage occurs from late spring to late summer.

MANAGEMENT

Citrus rust mite tends to occur together with BROAD MITE but usually in greater numbers. Both species thrive in warm, humid conditions. Monitor rust mite from early spring through summer. On orange trees, look for rust mites on young foliage in early spring; by late spring, most of the population will be on fruit. On lemon, rust mites are mostly on fruit throughout the season. To identify previous infestations, check outside fruit for scarred rind tissue. To assess current season levels, examine small green fruit on the inside of the canopy. A 10X to 15X hand lens is necessary to identify these minute mites. They usually feed in protected places, such as the stylar end of the fruit. When populations are high, the mites move over the entire fruit. No effective natural enemies are known, but general mite predators feed on rust mites at times.

Once you find one or more infested fruit and if rust mites were a problem the previous year, watch the orchard closely. Threshold levels depend on last year's rust mite problems and current market conditions. If the population increases quickly or if scarring appears, a treatment is generally required. In some cases, the infestation is localized and a spot treatment may be sufficient for control.

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.
A.	SPIRODICLOFEN
	(Envidor) 2SC	13 fl 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: 23
	COMMENTS: Works by contact with the mite so thorough coverage is important. Only one application per season allowed.
B.	DIFLUBENZURON*
	(Micromite) 80WGS	6.25 oz/acre (OC or IC)	12	21
	RANGE OF ACTIVITY: Pests: intermediate (katydids, peelminer, leafminer, grasshoppers); Natural enemies: predatory beetles
	PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 15
	COMMENTS: Not registered for use on lemons.
C.	ABAMECTIN*
	(Agri-Mek, etc.)	10 fl oz/acre (OC or IC)	12	7
	RANGE OF ACTIVITY: Pests: intermediate (citrus thrips, mites, leafminers); Natural enemies: predatory mites and thrips
	PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 6
	. . . PLUS . . .
	NARROW RANGE OIL
	(415)	0.25%	4	when dry
	MODE OF ACTION: Improves translaminar movement and persistence of insecticide.
	RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects/mites); Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: short
	COMMENTS: For use on all varieties. Apply in 50–200 gal water/acre. To avoid potential phytotoxicity of oil to the fruit, do not apply 30 days before or after a sulfur application and do not apply to small fruit (less than 1 inch in diameter) on a day when the ambient temperature has or is expected to exceed 95°F or when the relative humidity has or is expected to drop below 20%.
D.	MICRONIZED SULFUR#
	(Thiolux 80%)	20 lb/acre (OC or IC)	24	0
	RANGE OF ACTIVITY: Pests: broad (mites, citrus thrips); Natural enemies: most
	PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
	MODE OF ACTION: Not available.
	COMMENTS: For use on all varieties. Do not apply during or preceding high temperatures. Do not apply in any spray containing oil or within 21 days of a previous oil spray. May lead to citrus red mite or mealybug flareups.
E.	WETTABLE SULFUR#	45–60 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 or within 2 months of a previous oil spray. Do not apply oil 60–90 days after a sulfur treatment. Not recommended for use in the San Joaquin Valley.
F.	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.
G.	CHLORPYRIFOS*
	(Lorsban) 4E	9-12 pt/acre (OC to IC)	5 days	see comments
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short (low rates), intermediate (high rates); Natural enemies: short (low rates), intermediate (high rates)
	MODE OF ACTION GROUP NUMBER1: 1B
	. . . PLUS . . .
	NARROW RANGE OIL
	(415)	0.25%	4	when dry
	RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects/mites); Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: short
	MODE OF ACTION: Improves translaminar movement and persistence of insecticide.
	COMMENTS: Addition of chlorpyrifos to dilute oil gives faster control than oil alone, but rate of control for subsequent applications will diminish as resistance develops. It also causes thrips outbreaks, especially if used early season, and may lead to ridging of fruit. Apply this material in Sept.-Oct. only if several pests, such as citrus bud mite, citrus thrips, and ants, need to be controlled in addition to citrus bud mite. Do not apply chlorpyrifos in combination with spray oil when temperatures are expected to exceed 95°F (85–90°F in coastal areas). Preharvest interval is 21 days for up to 7 pt of chlorpyrifos/acre or 35 days for rates above 7 pt/acre. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
**	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/.

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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