Description of the Pest
Larvae are white to pinkish caterpillars with brown to black heads. Adult moths have gray wings with a copper spot on each wing tip. After overwintering as mature larvae in silken cells under loose bark on the tree, moths emerge from March to May. Adults mate and lay eggs; larvae feed on small fruit. A second generation appears in June and often a third one in August, depending on temperatures.
Damage
Fruit feeding by the codling moth has resulted in a high percentage of unmarketable fruit in some orchards. Codling moth larvae usually tunnel all the way to the pits of fruit; extrusions of frass or excrement are often found at the entrance of the larval tunnels.
Management
Codling moth is a pest in plums in the San Joaquin Valley that can be controlled with a single treatment timed using pheromone traps and degree-days.
Biological Control
An important egg and larval parasite is the braconid wasp, Ascogaster quadridentata. Natural enemies do help control codling moth but are unable to keep it below economic injury because it spends most of its larval stage inside the fruit, where it is protected from predators and parasites.
Cultural Control
Remove abandoned or unsprayed apple, pear, plum, apricot, and walnut trees near the plum orchard.
Monitoring and Treatment Decisions
Pheromone traps, degree-days (DD), and twilight temperatures are used to monitor codling moth activity. Soon after bud break or by March 15, place pheromone traps in your orchards to determine first moth emergence. See PHEROMONE TRAPS for more details and record results on a sampling form. The first biofix is the first date that moths are consistently found in traps and sunset temperatures have reached 62°F. To predict egg hatch, begin accumulating degree-days (DD) from the biofix, using a lower threshold of 50°F and an upper threshold of 88°F. Remove trapped insects from the trap bottom after you count and record information on the monitoring form .
Population levels of codling moth vary greatly from one area to another and from one variety of plums to another. If codling moth has caused damage in previous years, consider treating for this pest.
First generation egg hatch
Time the first spray for the beginning of egg hatch to kill emerging larvae 250-300 DD after the first biofix.
Second and third generation egg hatch
Use pheromone trap catches to detect an increase in flight activity around 1060 DD from the previous biofix, which signals the start of the next moth flight. If treatment is warranted, a single application is usually sufficient. Make this application when 250 DD have accumulated from the second or third biofix.
Calculate degree-days for codling moth in plum for your location using the codling moth pest model or degree-day table. To learn more about using degree-days to time insecticide applications, watch the degree-days video.
Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program. See FRUIT EVALUATION AT HARVEST. Record results on a monitoring form .
| Common name | Amount to use** | 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. | |||||
| A. | METHOXYFENOZIDE | ||||
| (Intrepid) 2F | 10–16 fl oz | — | 4 | 7 | |
| MODE OF ACTION GROUP NUMBER1: 18A | |||||
| COMMENTS: An insect growth regulator that provides 10 to 18 days of residual protection, depending on the rate of application and nut expansion. Kills young larvae but does not kill adult moths. It is a reduced risk insecticide that has little or no effect on beneficial insects and mites. Only use in orchards with low-to-moderate codling moth populations. Spray coverage is extremely important. Do not apply to large trees unless adequate spray coverage can be verified. Use no less than 100 gal water/acre for ground applications. Sprayer speed should not exceed 1.5 mph. The use of Latron B-1956, CS-7, or similar sticker/spreader is highly recommended. Apply at the beginning of egg hatch, which is earlier than organophosphate or carbamate insecticide timings. It is recommended that methoxyfenozide be applied at 200 DD after the first biofix. Do not apply more than 24 fl oz/acre/application or more than 64 fl oz/acre/season. | |||||
| B. | PHOSMET | ||||
| (Imidan) 70WP | 4.25 lb | 1 lb | 3 days | 7 | |
| MODE OF ACTION GROUP NUMBER1: 1B | |||||
| C. | CARBARYL* | ||||
| (Sevin) 80S | 3 lb | 1lb | 12 | 1 | |
| MODE OF ACTION GROUP NUMBER1: 1A | |||||
| COMMENTS: May cause increased spider mite problems; not recommended for routine use, especially early in the season. | |||||
| * | Permit required from county agricultural commissioner for purchase or use. |
| ** | For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate applications, use 80-100 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. |
| 1 | Rotate insecticides 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; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B. Mode-of-action group numbers for insecticides and miticides (un=unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). |
| — | Not recommended or not on label. |