Agriculture: Plum Pest Management Guidelines

American Plum Borer

  • Euzophera semifuneralis
  • Description of the Pest

    The forewings of the adult moth are gray with brown and black markings. The wingspan is about 0.75 inch. Young larvae are white with a large, dark brown head. Mature larvae are about 1 inch long, dusky white, pinkish or dull green in color. Reddish orange frass, webbing, and gum pockets indicate their presence. They overwinter as mature larvae in a cocoon within the tree. There are three to four generations each year.


    Larvae bore into the tree leaving reddish orange frass and gum pockets. The boring is most damaging to the scaffold crotches or graft unions of young trees. Vigorous trees will heal over, but with heavy, prolonged infestations, scaffolds may break with wind or a heavy crop.


    Monitor young orchards in spring and summer for frass and gum pockets. If larvae are present, spray trees from 1 foot above the scaffold crotch to 1 foot below, two to three times during the growing season. The first application should be mid- to late April and subsequent applications at 6-week intervals to kill adults before they can lay eggs. Remove and destroy infested wood or heavily infested trees.

    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.
    A. DIAZINON* 50WP 1 lb/100 gal water 24 21
      COMMENTS: Do not exceed 4 lb diazinon 50WP/acre.
      (Sevin) 80S 3.75–5 lb/acre 12 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. 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.
    1 Rotate insecticides 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; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B. Mode-of-action group numbers for insecticides and miticides (un=unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee).
    Text Updated: 04/09
    Treatment Table Updated: 04/09