How to Manage Pests

UC Pest Management Guidelines

Citrus

Aphids

Scientific Names:
Black citrus aphid: Toxoptera aurantii
Cotton or melon aphid: Aphis gossypii
Spirea aphid: Aphis spiraecola

(Reviewed 2/17, updated 2/17)

In this Guideline:


Description of the Pests

The most common aphid on citrus in the coastal and intermediate districts of Southern California is the spirea aphid. In the San Joaquin Valley, the cotton or melon aphid is the most commonly found aphid on citrus. The three most common aphid species can be distinguished by color: spirea aphids are always bright green, black citrus aphids are shiny black, and the cotton aphid can range in color from yellow, to green, to dull black. A colony of cotton aphids is usually composed of several different color forms.

Most aphid species overwinter in the egg stage, and these eggs hatch in the spring into males and females that mate and produce live young. Subsequent generations do not require mating and produce live young that can result in a large increase in aphid numbers in a relatively short time.

Damage

Aphids feed on flower and leaf buds and on the underside of leaves (mainly feather growth), causing leaves to curl toward the stem. Spirea aphid, black aphid and cotton aphid can all transmit citrus tristeza virus. Aphids also secrete honeydew, which mainly comes from the excess sap ingested by the insect. Honeydew may be produced in sufficant quantities to cause objects to become sticky. This can eventually attract other pests such as ants or prevent leaves from acquiring proper sunlight for photosynthesis.

Management

Aphids are generally not a problem on citrus except on young trees or continually flushing varieties (varieties that continually have new leaf growth), because their numbers decline when the foliage hardens off and the natural enemies are very effective in controlling them. Natural enemies normally fully control aphids within 6 weeks and an insecticide application is rarely warranted. Treatment of aphids to prevent transmission of tristeza virus has been shown to be effective only if conducted over a large area (several miles in each direction) because aphids can fly long distances.

Biological Control

The principle parasites of aphids are braconids and chalcidoids (two families of parasitoid wasps). Lacewings, a number of coccinellid (e.g. lady beetles) and syrphid predators, parasites, and fungal diseases usually keep aphid numbers below damaging levels. A moderate number of aphids (about 40% of growth flushes infested) can be considered beneficial on mature trees because aphids and their honeydew provide a good food source for natural enemies of other pests early in the season when other hosts are not available.

Organically Acceptable Methods

Use biological control on organically managed citrus.

Resistance

Populations of cotton aphids in the San Joaquin Valley have been shown to have resistance to organophosphate, carbamate, and pyrethroid insecticides.

Treatment Decisions

On newly established trees and on new growth flushes on mature trees, it is not uncommon for aphids to cause curling of leaves and produce honeydew. Treatment is usually not warranted because citrus can tolerate extensive leaf curling without yield effects. Pesticide applications are reserved for special situations such as areawide treatment programs for managing citrus tristeza virus.

Common name Amount to use REI‡ PHI‡
(Example trade name) (type of coverage)** (hours) (days)
Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
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. CYANTRANILIPROLE
  (Exirel) 13.5–20.5 fl oz/acre (OC) 12 1
  RANGE OF ACTIVITY: Pests: psyllids, leafminer, aphids; Natural enemies: none
  PERSISTENCE: Pests: intermediate; Natural enemies: none
  MODE-OF-ACTION GROUP NUMBER1: 28
  ...PLUS...
  415 NARROW RANGE OIL 0.25–1% See label See label
  RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and 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: Do not make ground applications within 25 feet or air applications within 50 feet of water bodies. Do not exceed 61 oz of Exirel 200 SL or 0.4 lb a.i./acre of cyantraniliprole-containing products/acre per year. Apply by air in a minimum of 10 gallons/acre.
 
B. ACETAMIPRID
  (Assail 70WP) 1.1–2.3 oz/100 gal (OC) 12 7
  (Assail 30SG) 2.5–5.5 oz/100 gal (OC) 12 7
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
C. FLUPYRADIFURONE
  (Sivanto 200SL) 7–10.5 fl oz/acre 12 1
  RANGE OF ACTIVITY: Pests: sucking insects such as psyllids, soft scales and aphids; Natural enemies: parasitic wasps
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE-OF-ACTION GROUP NUMBER1: 4D
  COMMENTS: Safe for bees, and can be used during bloom. Do not exceed 28 fl oz Sivanto (0.365 lb a.i. flupyradifurone)/acre per year. Apply by air in a minimum of 10 gallons/acre.
 
D. THIAMETHOXAM
  (Actara) 3–4 oz/acre 12 0
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: long; Natural enemies: long
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
E. ABAMECTIN/THIAMETHOXAM
  (Agri-Flex)* 5.5–8.5 fl oz/acre 12 7
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 4A/28
  COMMENTS: Do not exceed a total of 8.5 fl oz of Agri-Flex or 0.047 lbs ai of abamectin containing products or 0.084 lb a.i. of thiamethoxam containing products per acre per growing season.
 
** OC - Outside coverage uses 100 to 250 gal water/acre.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) 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.
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).

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441

Insects, Mites, and Snails

E. E. Grafton-Cardwell, Lindcove Research and Extension Center, Exeter and Entomology, UC Riverside
J. G. Morse, Entomology, UC Riverside
D. R. Haviland, UC Cooperative Extension, Kern County and UC IPM Program
B. A. Faber, UC Cooperative Extension, Santa Barbara and Ventura counties

Acknowledgments for contributions to Insect, Mite, and Snails:
J. Barcinas, E.S.I., Corona, CA
R. Dunn, Badger Farming Co., Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
C. E. Kallsen, UC Cooperative Extension, Kern County
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
N. V. O'Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
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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