How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Amorbia is primarily a pest of avocado, but can also occasionally cause damage in citrus groves, primarily in southern California and the San Joaquin Valley. The larva has two dark horizontal lines on each side of its head and prothoracic shield that distinguish it from other caterpillars that occur in citrus. There are two to three generations a year.

DAMAGE

Amorbia larvae may feed on young fruit at petal fall. They also feed on new growth flushes, often rolling the leaves or tying leaves to fruit and feeding on the peel of young or maturing fruit and under the calyx. Damaged fruit often decays at the feeding site. Infestations generally occur in groves planted near avocado.

MANAGEMENT

Amorbia is generally managed by monitoring from petal fall through fall. Use selective (toxic to only a narrow group of insects) insecticides to preserve populations of natural enemies.

Biological Control
A variety of natural enemies attack egg, larval, and pupal stages of amorbia. One of the most effective egg parasites is the tiny wasp, Trichogramma platneri. Parasitized eggs are black. Mass releases of T. platneri are used for control in avocado. A tachinid fly and several parasitic wasps attack the larvae stages. The tachinid fly attaches its eggs near the head of the larva and the emerging maggots bore into the amorbia larva to develop inside.

Organically Acceptable Methods
Biological control and sprays of Bacillus thuringiensis and the Entrust formulation of spinosad are acceptable for use in organically managed citrus orchards.

Monitoring and Treatment Decisions
When monitoring for citrus thrips at petal fall, especially in groves near avocados, check under the button on the base of fruit for small amorbia larvae. Monitor larger larvae later in spring by looking for webbing and leaf rolls in young foliage and feeding damage on young and mature fruit located on the outside canopy.

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.	BACILLUS THURINGIENSIS ssp. KURSTAKI#
	(various)	Label rates (OC)	4	0
	RANGE OF ACTIVITY: Pests: narrow (caterpillars); Natural enemies: none
	PERSISTENCE: Pests: short; Natural enemies: none
	MODE OF ACTION GROUP NUMBER1: 11.B2
	COMMENTS: Can be used during bloom. Timing is important because of short residual period. Apply only during warm weather to control young, actively feeding worms. Use reduced wind velocity and drive 3 mph.
B.	CRYOLITE
	(Prokil Cryolite) 96	8–20 lb/acre (OC)	12	15
	(Kryocide) 96 WP	8–20 lb/acre (OC)	12	15
	RANGE OF ACTIVITY: Pests: intermediate (foliage feeders such as worms, katydids, and Fuller rose beetle); Natural enemies: few, if any
	PERSISTENCE: Pests: long, unless washed off by rain; Natural enemies: none to short
	MODE OF ACTION GROUP NUMBER1: 9A
	COMMENTS: Check label for variety. Use higher rate for larger trees. Slow-acting stomach poison that may take several days of warm weather to kill worms. Use reduced wind velocity and a speed of 3 mph. Do not exceed 90 lb/acre/season.
C.	SPINOSAD
	(Entrust)#	1.25–3 oz/acre (OC)	4	1
	(Success)	4–10 fl oz/acre (OC)	4	1
	RANGE OF ACTIVITY: Pests: narrow (thrips, orangeworms, katydids); Natural enemies: predatory thrips
	PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 5
	COMMENTS: Do not apply more than 0.45 lb a.i./acre/crop.
D.	CHLORPYRIFOS*
	(Lorsban) 4E	0.5–2 qt/acre (OC or A)	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
	COMMENTS: For use on all varieties. Do not apply more than twice/fruit year or make applications less than 30 days apart. During the bloom period, apply from 1 hour after sunset until 2 hours before sunrise. P.H.I. is 21 days for up to 7 pt/acre or 35 days for over 7 pt/acre.
E.	CARBARYL*
	(Sevin XLR Plus) 4F	2 qt/acre (OC)	12	5
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: long; Natural enemies: long
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on all varieties. During the bloom period, apply from 1 hour after sunset until 2 hours before sunrise. XLR Plus formulation is less toxic to honey bees than the 80S formulation when direct application to bees is avoided, and the spray residues have dried. Check with your local county agricultural commissioner regarding application restrictions during the bloom period.
F.	NALED
	(Dibrom) 8E	2 pt/acre (OC)	see comments	7
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on grapefruit, lemons, oranges, tangerines. This material is hazardous to bees. Do not apply during bloom. R.E.I. is 2 days for 1 pt or less/acre and 3 days for more than 1 pt.
G.	METHOMYL*
	(Lannate LV) 2.4	1.5–3 pt/acre (OC or A)	72	1
	RANGE OF ACTIVITY: Pests: broad (many insects) Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on grapefruit, lemons, oranges, tangerines, and tangelos. Apply as needed, except during daylight hours of the bloom period. This material is hazardous to bees. Do not apply during bloom.
H.	CARBARYL*
	(Sevin) 80S	2.5 lb/acre (OC)	12	5
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: long; Natural enemies: long
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on all varieties. This material is hazardous to bees. Do not apply during bloom or apply more than 25 lb per acre per crop.
**	A - Aircraft applications 5-20 gal water/acre.
	OC - Outside coverage uses 100–250 gal water/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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