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How to Manage Pests

UC Pest Management Guidelines

French prunes.


Fruit Evaluation at Harvest

(Reviewed 6/06, updated 6/06)

In this Guideline:

Take a fruit damage sample in mid-July to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program. Fruit damaged by peach twig borer drops from the tree before harvest and would be missed in a later sample.


Randomly examine 1000 fresh fruit (40 fruit on 25 trees) for damage. These fruit could be picked from the tree or examined on the tree. Be sure to look high in the tree, especially on the south side. It takes about 15 minutes to examine 1000 fruit.

Examine fruit for damage from:

  • Larvae or larval feeding from peach twig borer, codling moth or other caterpillars.
    • Peach twig borer: shallow feeding holes; over time these may appear as scabs.
    • Codling moth: piles of frass at entrance holes; tunnel deep into fruit.
    • Leafrollers: tunneling into fruit; shallow holes or grooves in the fruit surface.
    • Green fruitworm: scarred and misshapened fruit.
  • San Jose scale: halos or spots on fruit surface. Also, look for presence of live or parasitized scale.
  • Brown rot.

Record on a monitoring form (100 KB, PDF) the number of fruit infested by larvae, type of larvae present or, if there are no larvae present, whether damage is surface feeding only or if the larvae penetrated the fruit. Record the number of fruit with live San Jose scale or parasitized San Jose scale as well as those with signs of brown rot.

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[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Prune
UC ANR Publication 3464
General Information
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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