Agriculture: Floriculture and Ornamental Nurseries Pest Management Guidelines

Root Mealybugs

  • Rhizoecus spp.
  • Description of the Pest

    Root mealybugs are belowground dwelling mealybugs that feed on the roots of plants. These mealybugs have a thin, uniform waxy coating and lack the terminal wax filaments typical of their foliar-feeding relatives.


    The only outward sign of root mealybug feeding may be a decline in the health of infested plants. When plants are removed from the pot, the whitish mealybugs feeding on the roots are then observed.


    Biological Control

    Biological control has not been investigated.

    Cultural Control

    Discard infected and surrounding plants. Control ants.

    Monitoring and Treatment Decisions

    Examine plant root balls when monitoring and when plants are declining. The presence of ants climbing on the plant can also indicate a problem with mealybugs. Rogue and discard infected plants. Treat with a soil drench or discard the surrounding plants.


    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.
    neonicotinoid A. imidacloprid
    (Marathon 1G)
    (Marathon II)
    OHP 12 4A Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops.  
      (Marathon 60 WP)       As above, but apply only as a drench.  
    organophosphate A. acephate
    (Acephate 97UP)
    United Phosphorus 24 1B  
    B. acephate
    (Orthene T,T&O Spray)
    Valent 24 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse, 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.
    pyrethroid A. bifenthrin
    (Talstar Professional)
    FMC 12 3 Label permits low-volume application.
    B. cyfluthrin
    (Decathlon 20 WP)
    OHP 12 3 Label permits low-volume application.
    C. fenpropathrin*
    (Tame 2.4 EC Spray)
    Valent 24 3 Label permits low-volume application.
    D. fluvalinate
    (Mavrik Aquaflow)
    Wellmark 12 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal.
    E. permethrin
    FMC 12 3 Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, diffenbachia and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year.
    A. cyfluthrin/imidacloprid
    OHP 12 3/4A  
    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 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.
    * Restricted use material. Permit required for purchase or use.
    Text Updated: 05/10
    Treatment Table Updated: 05/10