Agriculture: Citrus Pest Management Guidelines

Orange Tortrix

  • Argyrotaenia (=citrana) franciscana
  • Description of the Pest

    (View Caterpillar ID Key) (PDF)

    The larva of the orange tortrix is a greenish to straw-colored caterpillar with a straw-colored head and prothoracic shield. The major distinguishing characteristic between orange tortrix and omnivorous leafroller caterpillars is that the small mounds at the base of the bristles on the side and back of the omnivorous leafroller are white, whereas on the orange tortrix they are not.

    Orange tortrix larvae feed inside nests spun around plant parts. The larvae pupate in dense cocoons inside the nests and adult moths emerge in 8 days to 3 weeks, depending on temperature. Female moths lay 50 to 150 eggs on smooth surfaces such as stems, fruit, and the upper surface of leaves. In coastal areas, orange tortrix may have more than three generations a year, whereas in intermediate districts it has two or three. It is not a problem in the Central Valley.

    Damage

    Orange tortrix is primarily a pest on Valencias and navel oranges in Southern California. First generation orange tortrix larvae feed on leaves. Second generation larvae appear when the growth is hardening off and move preferentially to young fruit and feed around the button. This feeding causes only superficial scars. Later generations feed among clusters of ripening fruit, eating holes into the rind that allow decay organisms to enter; the fruit usually drops within 1 to 2 weeks.

    Management

    Manage orange tortrix by monitoring throughout spring and summer and applying insecticides when necessary. Use selective (toxic to only a narrow group of insects) insecticides to preserve natural enemies.

    Biological Control

    Several parasites and predators attack orange tortrix. The most common parasites are two wasps, Apanteles aristoteliae and Exochus sp. These wasps lay their eggs in tortrix larvae and the parasites develop within. Apanteles pupates in a white cocoon outside the dead larvae, whereas Exochus pupates inside the larva and emerges through a round exit hole.

    Organically Acceptable Methods

    Use biological control and sprays of Bacillus thuringiensis in organically managed citrus orchards.

    Monitoring and Treatment Decisions

    While orange tortrix larvae should be monitored throughout spring and summer, the period from May through July is especially important. At 7- to 10-day intervals, look for orange tortrix and evidence of parasitism mainly on the south and east quadrants of trees. If 15 larvae are found per hour of search on oranges and grapefruit, or 30 larvae per hour of search on lemons, an insecticide application may be warranted, depending on the level of parasitism.

    Common name Amount to use REI‡ PHI‡
    (Example trade name) (type of coverage)** (hours) (days)
    Not all registered pesticides are listed. 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. Always read the label of the product being used.
    A. BACILLUS THURINGIENSIS ssp. KURSTAKI#
    (various) Label rate (OC) 4 0
    RANGE OF ACTIVITY: Pests: narrow (caterpillars); Natural enemies: none
    PERSISTENCE: Pests: short; Natural enemies: none
    MODE-OF-ACTION GROUP NUMBER1: 11A
    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: 8C
    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. Use of Prokil Cryolite 96 allowed under a supplemental label.
    C. CARBARYL*
    (Sevin XLR Plus) 2–3 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.
    D. NALED
    (Dibrom 8 Emulsive)* 1–2 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. Do not apply during bloom.
    E. METHOMYL*
    (Lannate LV2.4) 1.5–3 pt/acre (OC or A) 72 (3 days) 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.
    ** A - Aircraft applications 5 to 20 gal water/acre.
    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.
    # Acceptable for use on organically grown produce.
    * 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 (un = unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee).
    Text Updated: 02/17
    Treatment Table Updated: 02/17