How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Citrus bud mite is very small, elongated and somewhat tapered at the posterior end, and has four legs at the front end near the mouth. Adult females lay about 50 eggs mostly in the bud scales of recent growth. Populations peak in summer, and summer and fall blooms are most likely to suffer damage.

DAMAGE

Citrus bud mite is primarily a pest of coastal lemons but in recent years has also been found in interior regions of southern California. The mites feed inside the buds, killing them or causing a rosettelike growth of the subsequent foliage and distortion of flowers and fruit, which may or may not reduce yield and/or fruit quality.

MANAGEMENT

Recent research has failed to show any consistent impact from bud mite feeding under current oil treatment regimes, especially in Lisbon lemons and is thought to be offset by the negative phytotoxic effects of oil. Research has also yet to be done to determine if abamectin plus oil treatments of bud mite are economically justified. To detect bud mites before damage occurs, check buds on green angular twigs from mid-spring to autumn. Collect one bud from each of 50 randomly chosen trees throughout the orchard. Dissect the buds under a microscope or use a 20X hand lens to determine the percent of buds infested with one or more live mites. As an alternative to dissecting buds, bud infestation can be estimated from infested fruit buttons. Collect one green fruit, about 1.25 to 2 inches in diameter, from 50 trees scattered throughout the orchard. Remove the button and record whether the button or the fruit beneath the button is infested with live bud mites. The relationship between fruit and bud infestations is not linear, but a fruit infestation of 15 to 20% indicates a bud infestation of about 45 to 50%.

No bud mite threshold had been established; levels as high as 80% bud infestation have failed to cause consistent or predictable economic losses. If a reduction in bud mite populations is desired, apply treatments 2 to 3 months before the bloom that is to be protected.

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.	FENBUTATIN OXIDE*
	(Vendex) 50W	1–2 lb/acre (LV)	48	7
	RANGE OF ACTIVITY: Pests: narrow (mites); Natural enemies: predatory mites
	PERSISTENCE: Pests: short; Natural enemies: short
	MODE OF ACTION GROUP NUMBER1: 12B
	. . . PLUS . . .
	NARROW RANGE OIL
	(415, 440)	10 gal/acre (LV)	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: Contact including smothering and barrier effects.
	COMMENTS: Do not apply during bloom. To help prevent development of resistance, alternate with dilute oil sprays. Potential of phytotoxicity to leaves, especially if applied during hot weather. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
B.	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)	0.25–1%	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: For use on all varieties. Apply in 500–1,000 gal/acre.
C.	NARROW RANGE OIL (UR 92%)
	(415, 440)	1.2–1.4% (TC)	4	when dry
	. . . or . . .
	NARROW RANGE OIL (UR 99%)
	(415, 435, 440, 455)	1.2–1.4% (TC)	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: Contact including smothering and barrier effects.
	COMMENTS: Can apply anytime between March and Nov. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
D.	CHLORPYRIFOS*
	(Lorsban) 4E	0.5 pt/100 gal (OC or 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)	0.5–1.4%	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: Contact including smothering and barrier effects; also improves translaminar movement and insecticide persistence.
	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 rust 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). P.H.I. 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.
**	LV - Low-volume uses 20–100 gal/acre.
	OC - Outside coverage uses 100–250 gal water/acre.
	IC - Intermediate coverage uses 250–600 gal/acre.
	TC - Thorough coverage uses 750–2,000 gal water or more/acre, depending on tree size.
+	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 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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