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UC Pest Management Guidelines


Colony of California red scale.

Olive

California Red Scale

Scientific Name: Aonidiella aurantii

(Reviewed 1/08, updated 1/09)

In this Guideline:


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.

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.

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** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to the impact on natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
Postbloom (Late May through June when crawlers are present)
A. NARROW RANGE OIL# 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 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) 80S 1–1.25 lb 12 14
  MODE OF ACTION GROUP NUMBER1: 1A
  COMMENTS: Do not exceed 2 applications/year. This material is very destructive to most natural enemies. 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# 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. Do not apply any oil between August 20 and harvest to olives used for Spanish or green-ripe processing because of the risk of fruit spotting. 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 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) 80S 1–1.25 lb 12 14
  MODE OF ACTION GROUP NUMBER1: 1A
  COMMENTS: Do not exceed 2 applications/year. This material is very destructive to most natural enemies. 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# 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 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/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.
 
** Amounts per 100 gal water (except where otherwise stated), using 400-500 gal solution per acre.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) 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). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Olive
UC ANR Publication 3452
Insects and Mites
F. G. Zalom, Entomology, UC Davis
P. M. Vossen, UC Cooperative Extension, Sonoma County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
M. W. Johnson, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
G. S. Sibbett, UC Cooperative Extension, Tulare County
L. Ferguson, Pomology, UC Davis

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