Description of the Pest
European fruit lecanium, also known as the brown apricot scale, occurs throughout the Central Valley. The adult female's domed shell is shiny brown, about 0.4 inch in diameter. Eggs are laid in spring and hatch from May to July. The young develop through the remainder of the season and overwinter on twigs and small branches as partly grown crawlers. There is one generation each year.
Damage
The chief injury is the production of honeydew that, in large amounts, can damage leaves and fruit. Sooty mold growing on the honeydew can cause blackened areas on leaves and fruit. For many years it was rare to see this pest due to the standard practice of applying oil during the dormant season. In recent years a reduction in the use of dormant sprays has caused this pest to be seen more often, though damaging levels are still not common.
Management
Natural enemies frequently keep lecanium scale below damaging numbers. If treatment is needed, oil during dormancy or delayed dormancy is the best treatment. Use dormant spur sampling to determine need for treatment.
Biological Control
Many natural enemies and summer temperatures consistently over 100°F help to control European fruit lecanium. Common predators include lady beetles (Chilocorus orbus, Hyperaspis spp., Rhyzobius lophanthae), lacewings, the predaceous sap beetle (Cybocephalus californicus), and predatory seed bugs (Phytocoris spp.). Parasites include, Coccophagus spp., Encarsia spp., and Metaphycus spp. Frequently, scales found during the growing season are heavily parasitized.
Organically Acceptable Methods
Naturally occurring biological control and certain oil sprays are organically acceptable.
Monitoring and Treatment Decisions
To determine if a dormant treatment is warranted, follow the sampling and treatment threshold guidelines in the section DORMANT SPUR SAMPLING. Examine scales during summer for parasitism before deciding to spray; if parasites are not present and treatment is necessary, a summer oil spray can be applied. When treatment is necessary, however, it is best to spray when leaves are off during the dormant or delayed dormant period. Oil alone is usually all that is required to manage this pest in the dormant season within an IPM program; the addition of another insecticide is necessary only when infestations are severe.
| 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. | ||||
| DORMANCY OR DELAYED-DORMANCY | ||||
| A. | DORMANT OIL such as: | |||
| DORMANT FLOWABLE EMULSION | 6 gal | 12 | 0 | |
| NARROW RANGE OIL# | 4 gal | See label | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: Oil alone can control moderate levels of scale and is often compatible with insecticides applied for other target pests. Check for compatibility with other insecticides or fungicides when used in a tank mix. Check with certifier to determine which products are organically acceptable. | ||||
| SPRING OR SUMMER | ||||
| A. | NARROW RANGE OIL# | |||
| (Omni Supreme) | Label rates | See label | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: Monitor before treating to determine if parasites are present. If scales are parasitized, a spray may not be necessary. Be sure that trees are well watered to avoid phytotoxicity. Works by contact activity only so good coverage is essential. Check with certifier to determine which products are organically acceptable. | ||||
| ‡ | 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 these two intervals is the minimum time that must elapse before harvest may occur. |
| * | Permit required from county agricultural commissioner for purchase or use. |
| # | Acceptable for use on organically grown produce. |
| 1 | Rotate pesticides 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; pesticides with a 1B group number should be alternated with pesticides that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee). |