Agriculture: Pomegranate Pest Management Guidelines

Omnivorous Leafroller

  • Platynota stultana
  • Description of the Pest

    Omnivorous leafroller can be a significant pest. The larvae are cream colored with black or brown head capsules and resemble other leafrollers, except that they have white tubercles at the base of each bristle along the top of the abdomen. Omnivorous leafrollers are more common in interior valleys and Southern California mountain orchards, especially those next to vineyards, than in orchards in coastal areas or at higher elevations of the Sierra Foothills. Orchards may be invaded by omnivorous leafroller moths that develop on host plants outside the orchard. Infestations are often spotty, making monitoring difficult. They have three to four generations per year.

    The adult omnivorous leafroller is bell-shaped with blackish gray snoutlike mouthparts that protrude forward from the head. Forewings are dark, rusty brown with a tan tip. Size varies from 0.38 to 0.5 inch (9.7–12.7 mm). Omnivorous leafroller larvae overwinter in weeds. In spring, larvae complete their development, and moths emerge and lay shinglelike egg masses on leaves, which hatch after about 5 days. The larva does not roll leaves as its name suggests. Instead, it weaves a silk nest between two leaves, a leaf and a fruit, or where two fruit touch.


    On pomegranates, the larvae typically carve surface grooves where two fruit touch or where the larvae have tied a leaf to the fruit surface. Often the larvae tunnel into the fruit. If skin penetration occurs, pathogens may become established internally and grow on the arils with no visible, external symptoms. If the fruit is not culled before juicing, the product may be ruined.


    Insecticide sprays timed according to degree-day accumulations may be used. Mating disruption can be effective if started in February or early March when moths first fly. A second hanging of dispensers may be needed in late summer. Careful monitoring, including occasional fruit and foliage inspections, is critical to the success of these management tools.

    Biological Control

    More than 10 species of parasites have been recorded from omnivorous leafroller. However, seldom does mortality from these parasites exceed 10%. Predators such as lacewings, minute pirate bugs and spiders also feed on omnivorous leafroller larvae that are feeding on leaves. Biocontrol does not provide control of larvae that have entered fruit.

    Cultural Control

    During the first flight, adults oviposit on weed hosts near the orchards, so weed control early in the season reduces the second generation that may cause damage to pomegranate orchards. Manage orchard weeds during late winter. Disc clusters and weeds to bury overwintering larvae living on weeds in ground duff. During dormancy, prune out old fruit and destroy by flailing or shredding.

    Organically Acceptable Methods

    Applications of Bacillus thuringiensis, spinosad (Entrust), and the use of mating disruption are organically acceptable.

    Monitoring and Treatment Decisions

    • Monitor omnivorous leafroller adults with a minimum of 2 traps per block first placed in orchards at 5 to 6 feet high in the canopy around February 15 to 20.
    • For blocks over 20 acres use an additional 1 trap per 20 acres.
    • Check the traps at least one to two times per week until the first consistent moth catch (the biofix date).

    A treatment threshold based on trap moth catches has not been established. However, traps can be used to time a pesticide application.

    Mating Disruption

    If mating disruption is to be used, place pheromone dispensers out in February to early March or at the biofix. To ensure coverage through the long growing season, a second hanging of dispensers may be needed in the late summer (July). In some orchards, putting dispensers out once in mid-May, before the second-generation moth flight begins, can provide control.

    Pheromone dispensers will disrupt pheromone trap catches. Several times throughout the season, inspect foliage and fruit for leafrollers and damage to confirm that mating disruption is working. Several moths in traps can be an indication that pheromone disruption is not working.


    Timing insecticides using degree-days in pomegranate has not been studied but should resemble the timings that are used in stone fruits. Apply an insecticide about 700 to 900 degree-days (lower development threshold 48°F, upper threshold 87°F) after the first flight. If applying Bacillus thuringiensis, timing must be precise since Bacillus thuringiensis must be ingested to work and is most effective against small larvae. Bacillus thuringiensis has a short residual, should be applied twice about 7 to 10 days apart, is slow acting, and may not reduce numbers quickly.

    Continue monitoring trap catches weekly until the second-generation flight, about 1200 degree-days after the first flight in late June, treating 700 to 900 degree-days after the first flight.

    The third generation, in late July or early August, is most damaging to fruit. If earlier control measures were adequate, additional third generation measures should not be necessary, but if pheromone traps or fruit inspections indicate a continuing problem, additional sprays can be aimed at the third moth flight 700 to 900 degree-days after the flight begins. However, no insecticide is effective against larvae that have already entered the fruit.

    Common name Amount per acre REI‡ PHI‡
    (Example trade name)   (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.
      (Altacor) 3–4.5 oz 4 1
      (Delegate WG) 4–7 oz 4 1
      COMMENTS: Highly toxic to bees. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
      (Intrepid 2F) 8–16 fl oz 4 7
      (Lannate SP) 1 lb 48 14
      COMMENTS: Disruptive to natural enemies of mealybugs, caterpillars, soft scales, aphids, and other pests. Use of this pesticide may result in outbreaks of these pests. Methomyl is also toxic to bees and should not be applied when bees are actively foraging.
      (Entrust)# 1.25–2.5 oz
    (0.45–0.83 oz/100 gal)
    4 7
      COMMENTS: Highly toxic to bees. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
      (various products) Label rates 4 0
      COMMENTS: Least harmful to natural enemies. Bacillus thuringiensis is a stomach poison and must be consumed by the leafroller. Must be applied when larvae are small. A second or third spray may be required. Most effective if applied when weather forecasts predict 3 to 4 days of warm, dry weather. Larvae are more active and feed more in warm weather than in cooler or rainy weather.
      (Checkmate OLR)# 100–150 units
    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.
    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).
    Not applicable.
    * Permit required from county agricultural commissioner for purchase or use.
    Text Updated: 12/18
    Treatment Table Updated: 12/18