Description of the Pest
An armored scale, the California red scale is similar to olive scale and resembles a small encrustation on the plant. The adult female has a thin, circular shell, 0.10 inch (2.5 mm) in diameter. The reddish body color is visible through the shell. When mature, females produce 100 to 150 eggs. Crawlers hatch and emerge from under the female cover at a rate of two to three per day. Crawlers move around to find a suitable place to settle and can be spread about by wind, birds, or picking crews. There are several generations a year.
Damage
California red scale does not discolor fruit, which distinguishes its damage from that of olive scale and oleander scale. All parts of the olive tree are infested. Infested fruit are rendered worthless.
Management
California red scale is effectively controlled by parasitic wasps in most areas of the state except the San Joaquin Valley. In areas where it causes damage, particularly where citrus is grown nearby, monitoring for this pest will help to determine if treatments are necessary. Control ants in the orchard because they disrupt biological control (for more information, see ANTS).
Biological Control
California red scale parasites include Aphytis melinus and Comperiella bifasciata. Aphytis parasites leave small, round exit holes in the scale's cover whereas Comperiella bifasciata has a larger, more irregular exit hole. Where insecticides such as carbamates (IRAC Group 1A), organophosphates (1B), and pyrethroids (3) are used, biological control will be disrupted. Be sure to monitor scale populations if disruptive insecticides are used.
Organically Acceptable Methods
Biological control and certain oil sprays are acceptable to use in an organically certified crop.
Monitoring and Treatment Decisions
In the San Joaquin Valley, monitor red scale by examining fruit, twigs, and leaves for scales, or by applying double-sided sticky tape to branches and examining it for crawlers. Treat the first brood in late May and June or the second brood in late July and August. Apply first brood treatment when scale crawlers are seen moving on to the fruit. Treating scales between broods in early July is not recommended. A postharvest treatment is also effective.
| Common name | Amount to use** | 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. | ||||
| POSTBLOOM (LATE MAY THROUGH JUNE WHEN CRAWLERS ARE PRESENT) | ||||
| A. | NARROW RANGE OIL# | |||
| (Organic JMS Stylet Oil, etc.) | Label rates | 4 | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: Effective against light to moderate infestations, especially when used in conjunction with pruning to open the orchard canopy. Most effective when applied against the crawler stage. Spray at night or early morning if temperatures are expected to exceed 90°F during the day. Check with certifier to determine which products are organically acceptable. | ||||
| B. | PYRIPROXYFEN | |||
| (Esteem 0.86EC) | 13–16 fl oz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 7C | ||||
| COMMENTS: Insect growth regulator. Has no activity on adult stage, but hatching of eggs laid by treated adults will be suppressed. Most effective when applied against the crawler stage. Use higher rate for heavy scale pressure. | ||||
| C. | NARROW RANGE OIL | |||
| (various products) | 1.5 gal | 4 | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: For heavy to severe infestations, add the following insecticide to the oil spray. Spray at night or early morning if temperatures are expected to exceed 90°F during the day. | ||||
| . . . plus . . . | ||||
| CARBARYL* | ||||
| (Sevin SL) | 5.0–7.5 qt | 12 | 14 | |
| MODE-OF-ACTION GROUP NUMBER1: 1A | ||||
| COMMENTS: Do not exceed 2 applications per year. This material is very destructive to most natural enemies. To protect honeybees, apply only during late evening, night, or early morning when bees are not present. Do not spray directly nor allow drift onto blooming crops or weeds where bees are foraging. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. | ||||
| SUMMER (JULY 15–AUGUST) | ||||
| A. | NARROW RANGE OIL# | |||
| (Organic JMS Stylet Oil, etc.) | Label rates | 4 | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: Effective against light to moderate infestations, especially when used in conjunction with pruning to open the orchard canopy. Most effective when applied against the crawler stage. Spray at night or early morning if temperatures are expected to exceed 90°F during the day. Check with certifier to determine which products are organically acceptable. | ||||
| B. | PYRIPROXYFEN | |||
| (Esteem 0.86EC) | 13–16 fl oz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 7C | ||||
| COMMENTS: Insect growth regulator. Has no activity on adult stage, but hatching of eggs laid by treated adults will be suppressed. Most effective when applied against the crawler stage. Use higher rate for high scale numbers. | ||||
| C. | NARROW RANGE OIL | |||
| (various products) | 1.5 gal | 4 | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: For heavy to severe infestations, add the following insecticide to the oil spray. Do not apply any oil between August 20 and harvest to olives used for Spanish or green-ripe processing due to fruit spotting. Spray at night or early morning if temperatures are expected to exceed 90°F during the day. | ||||
| . . . plus . . . | ||||
| CARBARYL* | ||||
| (Sevin SL) | 5.0–7.5 qt | 12 | 14 | |
| MODE-OF-ACTION GROUP NUMBER1: 1A | ||||
| COMMENTS: Do not exceed 2 applications per year. This material is very destructive to most natural enemies. To protect honeybees, apply only during late evening, night, or early morning when bees are not present. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. | ||||
| POSTHARVEST (OCTOBER–NOVEMBER) | ||||
| A. | NARROW RANGE OIL# | |||
| (Organic JMS Stylet Oil, etc.) | Label rates | 4 | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: Effective against light to moderate infestations, especially when used in conjunction with pruning to open the orchard canopy. Most effective when applied against the crawler stage. Spray at night or early morning if temperatures are expected to exceed 90°F during the day. Check with certifier to determine which products are organically acceptable. | ||||
| B. | NARROW RANGE OIL | |||
| (various products) | 1.5 gal | 4 | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: For heavy to severe infestations, add the following insecticide to the oil spray. Spray at night or early morning if temperatures are expected to exceed 90°F during the day. | ||||
| . . . plus . . . | ||||
| METHIDATHION* | ||||
| (Supracide 25WP) | 2 lb | 48 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: 1B | ||||
| COMMENTS: Use with or without oil. Application of methidathion with, or closely following, a fungicide containing lime will negate the insecticide's effectiveness. The application of this material should precede the application of fungicides containing lime. Do not apply more than 12 lb/acre per year. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. To protect honeybees, apply only during late evening, night, or early morning when bees are not present. | ||||
| ** | Amounts per 100 gal water (except where otherwise stated), using 400-500 gal solution per 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. |
| * | Permit required from county agricultural commissioner for purchase or use. |
| # | Acceptable for use on organically grown crops. |
| 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). |