Agriculture: Apple Pest Management Guidelines

Apple Pandemis

  • Pandemis pyrusana
  • Description of the Pest

    Apple pandemis is primarily a pest in Central Coast orchards where it occurs in higher populations in cooler years and in cooler locations. Pandemis overwinters as first instar larvae in apple buds. Larvae become active in spring as the buds open up. Larvae are green caterpillars with a straw- or gold-colored head.

    Orange tortrix larvae are similar in appearance to apple pandemis but only occur together in the orchard during the month of July. There are two generations a year.

    Damage

    Overwintered larvae feed on blooms and on the surface of young fruit, causing them to drop or resulting in scarring and distortion. Summer generation larvae feed on leaf tissue and cause windowpaning. This windowpane can be used to distinguish between apple pandemis and orange tortrix.

    Windowpaning may also be caused by eyespotted bud moth, however, especially in organic orchards. In addition, when apple pandemis tie leaves to fruit, they cause shallow feeding scars that are also similar to those caused by eyespotted bud moth.

    Management

    Control measures aimed against first-generation apple pandemis during bloom and petal fall are generally more successful than in-season sprays because summer-generation eggs are laid in rolled leaves and larvae are protected from sprays when they hatch.

    Biological Control

    The parasitic wasp Enytus eureka and a tachinid fly in the genus Actia have been found parasitizing apple pandemis larvae; neither is abundant.

    Organically Acceptable Methods

    Sprays of Bacillus thuringiensis, the Entrust formulation of spinosad, and kaolin clay are organically acceptable.

    Monitoring and Treatment Decisions

    Overwintering larvae can be controlled with a delayed dormant application of oil and insecticide; however, these sprays pose water quality concerns and may pose some risks to raptors, aquatic invertebrates, beneficials, and other nontarget organisms. If a delayed dormant spray is not applied, sample for apple pandemis between green tip and pink bud; examine 100 fruit clusters per block for larvae. Treat if there are any apple pandemis larvae in the sample.

    Monitor the summer generations once a month in June, July, and August in conjunction with orange tortrix and eyespotted bud moth: take the first sample no later than mid-June. Examine 10 trees of each variety in each block for 4 minutes each. Each larva found, whether orange tortrix, apple pandemis, or eyespotted bud moth, correlates to about 1% fruit damage at harvest.

    The threelined leafroller (Pandemis limitata) pheromone trap can be used to monitor apple pandemis. Although this can give you an idea of when moths are flying, it will not provide an accurate assessment of populations in an individual block because traps draw moths in from native vegetation as well as from orchard trees.

    Common name Amount per acre** REI‡ PHI‡
    (Example trade name) (conc.) (dilute) (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.
     
    PETAL FALL TO HARVEST
     
    A. METHOXYFENOZIDE
      (Intrepid 2F) 8–16 fl oz 4 14
      MODE-OF-ACTION GROUP NUMBER1: 18
      COMMENTS: Functions as a larvicide (must be ingested for it to be effective).
     
    B. SPINOSAD
      (Entrust)# 2–3 oz 0.67–1 oz 4 7
      (Success) 6–10 fl oz 2–3.3 fl oz 4 7
      MODE-OF-ACTION GROUP NUMBER1: 5
      COMMENTS: Apply at petal fall when larvae are present. To prevent the development of resistance to this product, rotate to a material with a different mode of action after treating two consecutive generations. Do not apply more than 3 sprays per season directed at leafrollers. Do not apply more than 9 oz/acre per crop of Entrust or 29 fl oz of Success/acre per crop. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
     
    C. CHLORANTRANILIPROLE
      (Altacor) 3–4.5 oz 4 5
      MODE-OF-ACTION GROUP NUMBER1: 28
      COMMENTS: Do not apply dilute applications of more than 200 gal/acre; use 100–150 gal/acre for best results.
     
    D. SPINETORAM
      (Delegate WG) 4.5–7 oz 4 7
      MODE-OF-ACTION GROUP NUMBER1: 5
      COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
     
    E. BACILLUS THURINGIENSIS ssp. KURSTAKI#
      (various products) Label rates 4 0
      MODE-OF-ACTION GROUP NUMBER1: 11A
      COMMENTS: Bacillus thuringiensis is a stomach poison and must be consumed by the leafroller; therefore it is most effective when applied during warm, dry weather when larvae are actively feeding. Most effective against young larvae. Requires more than 1 treatment; apply second application 7 to 10 days after first.
     
    F. KAOLIN CLAY#
      (Surround WP) 25–50 lb 4 0
      MODE-OF-ACTION: Unknown. An inorganic insecticide.
      COMMENTS: Serves primarily as a barrier to oviposition and/or to prevent larvae from entering the fruit so early application and good coverage are important. Make the first application when larvae are detected and reapply in 7 to 14 days in 100–200 gal water/acre. A total of 3 treatments per generation may be required to keep fruit completely covered during the egg-laying period.
     
    SUMMER
     
    A. METHOXYFENOZIDE
      (Intrepid 2F) 8–16 fl oz 4 14
      MODE-OF-ACTION GROUP NUMBER1: 18
      COMMENTS: Functions as a larvicide (must be ingested for it to be effective).
     
    B. SPINOSAD
      (Entrust)# 2–3 oz 0.67–1 oz 4 7
      (Success) 6–10 fl oz 2–3.3 fl oz 4 7
      MODE-OF-ACTION GROUP NUMBER1: 5
      COMMENTS: To prevent the development of resistance to this product, rotate to a material with a different mode of action after treating two consecutive generations. Do not apply more than 3 sprays per season directed at leafrollers. Do not apply more than 9 oz/acre per crop of Entrust or 29 fl oz of Success/acre per crop. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
     
    C. CHLORANTRANILIPROLE
      (Altacor) 3–4.5 oz 4 5
      MODE-OF-ACTION GROUP NUMBER1: 28
      COMMENTS: Do not apply dilute applications of more than 200 gal/acre; use 100–150 gal/acre for best results.
     
    D. SPINETORAM
      (Delegate WG) 4.5–7 oz 4 7
      MODE-OF-ACTION GROUP NUMBER1: 5
      COMMENTS:Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
     
    E. BACILLUS THURINGIENSIS ssp. KURSTAKI#
      (various products) Label rates 4 0
      MODE-OF-ACTION GROUP NUMBER1: 11A
      COMMENTS: Least harmful to beneficials. Bacillus thuringiensis is a stomach poison and must be consumed by the leafroller; therefore it is most effective when applied during warm, dry weather when larvae are actively feeding. Most effective against young larvae. Requires more than 1 treatment; apply second application 7 to 10 days after first.
    ** For dilute application, rate is per 100 gal water to be applied in 300 to 500 gal water/acre, according to label; for concentrate applications, use 80 to 100 gal water/acre or lower if the label allows.
    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.
    * 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).
    Text Updated: 03/09
    Treatment Table Updated: 10/15