Description of the Pest
Filbertworm is a native insect found throughout California and is an occasional pest of pomegranate. The small, bronze, copper, or reddish-brown moths emerge in late spring to early summer. The moth is characterized by a thin, brown band running across the top pair of wings.
After emergence, eggs are laid singly, hatching in 8 to 11 days. Eggs are scalelike, flattened oval in shape, and similar in appearance to codling moth eggs. Filbertworm eggs are white when newly laid and turn darker as hatching approaches.
Larvae overwinter in organic matter or soil, can reach 0.5 inch (1.3 cm) in length, and range from beige to pink with a dark brown to black head. Pupation occurs in a silk cocoon the next spring. One generation with a partial second has been observed in cool areas such as Oregon. However in warm areas of California, two generations per year is probable, with second-generation adults appearing in the fall.
Damage
Filbertworm can cause serious damage in pomegranates. Infestations have been seen in only a few orchards, most of which are in close proximity to alternate hosts, such as oak.
In July, the larvae bore into the fruit similar to codling moth, a close relative. Like codling moth damage, frass is often found at the entrance of the larval tunnels.
Management
Cultural control methods, such as removing old fruit, can help reduce filbertworm numbers. Pheromone traps will help you determine the timing of sprays.
Cultural Control
Remove all unharvested fruit, or disc fruit on the ground under, to prevent buildup of numbers in the orchard.
Organically Acceptable Methods
Cultural control methods and applications of spinosad (Entrust) are acceptable for use on organically grown pomegranate.
Monitoring and Treatment Decisions
Monitor with pheromone traps in orchards with a history of filbertworm problems. Place pheromone traps in the orchard and nearby oak trees in mid-April. Put two traps 5 to 6 feet high in the canopy in a 10-acre orchard, adding one more trap for every 5 additional acres. Check weekly, correctly identifying moths in case other moth species are caught.
At this time, there are no treatment thresholds. If moths are being caught in traps, make pesticide applications during the peak of the flight.
Looking for moth eggs can also be helpful to determine if numbers are high enough to treat. Treatment timing determined by looking for fruit stings from larval entrances is probably too late for control. However, larval stings can be useful to determine if the next generation may cause damage.
| 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. | ||||
| A. | CHLORANTRANILIPROLE | |||
| (Altacor) | 3–4.5 oz | 4 | 1 | |
| MODE-OF-ACTION GROUP NUMBER1: 28 | ||||
| B. | METHOXYFENOZIDE | |||
| (Intrepid 2F) | 8–16 fl oz | 4 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 18 | ||||
| C. | SPINETORAM | |||
| (Delegate WG) | 4–7 oz | 4 | 1 | |
| MODE-OF-ACTION GROUP NUMBER1: 5 | ||||
| COMMENTS: Highly toxic to bees. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. | ||||
| D. | METHOMYL* | |||
| (Lannate SP) | 1 lb | 48 | 14 | |
| MODE-OF-ACTION GROUP NUMBER1: 1A | ||||
| 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. | ||||
| E. | SPINOSAD | |||
| (Entrust)# | 1.25–2.5 oz (0.45–0.83 oz/100 gal) |
4 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 5 | ||||
| COMMENTS: Highly toxic to bees. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. | ||||
| F. | BACILLUS THURINGIENSIS ssp. KURSTAKI# | |||
| (various products) | Label rates | 4 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: 11A | ||||
| COMMENTS: Least harmful to natural enemies. Bacillus thuringiensis is a stomach poison and must be consumed by the filbertworm. Must be applied when larvae are small. A second or third treatment 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. | ||||
| ‡ | 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 are assigned by IRAC (Insecticide Resistance Action Committee). |
| * | Permit required from county agricultural commissioner for purchase or use. |
| # | Acceptable for use on organically grown produce. |