Agriculture: Floriculture and Ornamental Nurseries Pest Management Guidelines

Armored Scale

  • California red scale: Aonidiella aurantii
  • Greedy scale: Hemiberlesia rapax
  • Oleander scale: Aspidiotus nerii
  • Oystershell scale: Lepidosaphes ulmi
  • San Jose scale: Diaspidiotus (=Quadraspidiotus) perniciosus
  • Description of the Pest

    The protective covering over armored scales is produced by molted skins and secretions from the scale. Unlike soft scales, the protective covering can be lifted off the body of the armored scale. High populations of these sucking insects give plant stems a crusty appearance. The first nymphal instar is called a crawler and has functional legs, while the remaining instars are attached to the leaf and do not move. Unlike soft scales, armored scales do not produce honeydew. Most armored scales have several generations a year.


    Along with the unsightly encrustations that are the bodies of the immobile scales, these scales inject toxic saliva that causes plants to decline.


    Biological Control

    Aphytis melinus is a commercially available parasite that is effective in controlling California red scale. For more information, see BIOLOGICAL CONTROL.

    Cultural Control

    Prune out and discard heavily infested plant parts. Exclusion of windblown crawlers can be accomplished by covering openings to the greenhouse with fine mesh screens.

    Monitoring and Treatment Decisions

    Carefully inspect new plants being brought into the production area to ensure that they are free of scales and other pests. Treat infested plants.

    Visual inspection of plants will help locate infestations and may permit localized treatments of hot spots. Treatment is generally warranted when scales are present. Optimum treatment timing is when crawlers are active; however, when there are overlapping, multiple generations, crawlers may emerge over a lengthy time, making multiple applications necessary.


    Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals

    Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact.

    Class   Pesticide (commercial name) Manufacturer REI1 Mode of action2 Comments
    botanical A. pyrethrin/PBO3
    (PT Pyrethrum TR)
    12 3/— An aerosol.
    insect growth regulator A. pyriproxyfen
    Valent 12 3 Do not apply more than 2 times per cropping cycle or per 6 months. Do not use through any type of irrigation system in California.
    B. s-kinoprene
    (Enstar II)
    Wellmark 4 7A Apply prebloom. Also labeled for low volume use.
    oil4 A. clarified hydrophobic extract of neem oil#
    (Triact 70)
    OHP 4 un Do not spray plants under stress. Target pest must be completely contacted with spray. Check label for list of plants that can be treated. May cause injury to flowers.
    B. horticultural oil5
    (Ultra-Fine Oil)
    (JMS Stylet Oil)
    JMS Farms


    Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions.
    organophosphate A. acephate
    (Acephate 97UP)
    24 1B  
    B. acephate
    (Orthene T,
    T&O Spray)
    Valent 24 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouses only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. Do not use through any type of irrigation system.
    C. acephate
    (PT 1300 Orthene TR)
    Whitmire MicroGen 24 1B An aerosol for greenhouse use only.
    D. malathion
    various 12 1B Not for greenhouse use.
    pyrethroid A. cyfluthrin
    (Decathlon 20WP)
    OHP 12 3 Label permits low-volume application.
    B. fluvalinate
    (Mavrik Aquaflow)
    Wellmark 12 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal.
    1  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.
    2 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).
    3 PBO = piperonyl butoxide
    4 Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs.
    5 Check with certifier to determine which products are organically acceptable.
    * Restricted use material. Permit required for purchase or use.
    # Acceptable for use on organically grown ornamentals.
    Text Updated: 05/10
    Treatment Table Updated: 05/10