How to Manage Pests

UC Pest Management Guidelines

Citrus

Amorbia (Western Avocado Leafroller)

Scientific Name: Amorbia cuneana

(Reviewed 9/08, updated 6/13)

In this Guideline:


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. 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.‡
(example trade name) (type of coverage)** (hours) (days)

  Calculate impact of pesticide on air quality
 
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.
 
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
  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) 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: unknown
  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.
 
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
 
D. CHLORPYRIFOS*
  (Lorsban Advanced) 2–7 pt/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 per 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) 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. Check with your local county agricultural commissioner regarding application restrictions during the bloom period.
 
F. NALED
  (Dibrom 8 Emulsive) 2 pt/acre (OC) 48 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.
 
G. METHOMYL*
  (Lannate LV2.4) 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.
 
** 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 ("un"=unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441

Insects, Mites, and Snails

  • E. E. Grafton-Cardwell, Entomology, UC Riverside and Kearney Agricultural Center, Parlier
  • J. G. Morse, Entomology, UC Riverside
  • N. V. O'Connell, UC Cooperative Extension, Tulare County
  • P. A. Phillips (emeritus), 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 Co., 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
  • 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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