Agriculture: Plum Pest Management Guidelines

Fruit Evaluation at Harvest

Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program.

Use monitoring form (PDF) with detailed treatment threshold information.

How to Sample

During the sorting process in the orchard randomly examine 100 fresh fruit from each bin for each variety. Distinguish damage caused by peach twig borer, obliquebanded and omnivorous leafrollers, codling moth, and San Jose scale.

Look for the presence of:

  • 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.
  • Look for the presence of live or parasitized San Jose scale and halos or spots on the fruit surface.

Record on a sampling form 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. Note that you may also see signs of ripe fruit rot.

Text Updated: 05/06