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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

American plum borer larvae bore in scaffold crotches of young trees.

Prune

American Plum Borer

Scientific name: Euzophera semifuneralis

(Reviewed 6/06, updated 4/09)

In this Guideline:

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.

DAMAGE

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.

MANAGEMENT

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 to kill adults before they can lay eggs. Shred or haul to the dump infested wood or heavily infested trees. The first application should be mid- to late April and subsequent applications at 6-week intervals.

Common name Amount to Use R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, impact on natural enemies and honey bees, and impact of the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. DIAZINON* 50WP 1 lb/gal water 24 21
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Do not exceed 4 lb diazinon 50WP/acre. Avoid drift and tailwater runoff into surface waters.
 
B. CARBARYL*
  (Sevin) 80S 3.75–5 lb/gal water 12 1
  MODE OF ACTION GROUP NUMBER1: 1A
 
+ 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.
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: Prune
UC ANR Publication 3464
Insects and Mites
C. Pickel, UC IPM Program, Sutter/Yuba counties
F. J. A. Niederholzer, UC Cooperative Extension, Sutter/Yuba counties
W. H. Olson, UC Cooperative Extension, Butte County
F. G. Zalom, Entomology, UC Davis
R. P. Buchner, UC Cooperative Extension, Tehama County
W. H. Krueger, UC Cooperative Extension, Glenn County
Acknowledgment for contributions to Insects and Mites:
W. O. Reil, UC Cooperative Extension Solano/Yolo counties

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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