1. UC IPM
  2. Agriculture
  3. Pear
  4. Sampling During Fruit Development
Agriculture: Pear Pest Management Guidelines

Sampling During Fruit Development

On This Page

During the fruit development season examine fruit and leaves for the presence of, or damage caused by, pear psylla, mites, mealybugs, caterpillars, aphids, sawfly (pearslug), thrips, and plant bugs.

Keep records of your observations (example form PDF).

How to Sample

Take weekly samples of shoots that contain a fruit cluster, one from the treetop and one at eye level, from each of 20 trees in a 20-acre block. Examine both leaves and fruit for pests.

Leaves

Use a 10 to 14X hand lens to examine 5 leaves per shoot (total of 200 leaves) for

  • Pear psylla (nymphs, eggs, and honeydew)
  • Mites
    • European red mite (on both top and eye-level shoots)
    • Twospotted and other webspinning spider mites (early season, primarily on eye-level shoots; later in season top and eye-level shoots)
  • Other pests
    • Aphids (russeting and honeydew)
    • Pearslug (eggs and larvae)
    • Pearleaf blister mite (damage)
    • Katydids (feeding damage and nymphs on trees and cover crop)

Fruit

Examine fruit for evidence of pests or damage:

  • Codling moth (stings and larval entries)
  • Obliquebanded leafroller (look where fruit touch)
  • Pear rust mite (russeting at calyx and stem ends)
  • Boxelder bugs (mostly in areas near riparian corridors)
  • Lygus bugs
  • Stink bugs (also do a 30-minute search for adults)

Decision Table

Sample type Pest Management decision

Leaves

 Pear psylla
  • If one or more shoots have psylla eggs or nymphs, treat according to the Pear Pest Management Guidelines.
European red mite
  • If 10 or fewer European red mites or eggs are found per 100 inspected leaves, don't treat.
  • If 11 to 50 are found, treat with oil according to the Pear Pest Management Guidelines.
  • If more than 50 are found, add a miticide with the oil according to the Pear Pest Management Guidelines.
Webspinning (e.g. twospotted) spider mites For Bartlett and Bosc varieties (thresholds for Asian pears and other varieties are generally higher):
  • If 1 to 50 mites per 100 leaves sampled, treat with oil according to the Pear Pest Management Guidelines.
  • If more than 50 mites per 100 leaves sampled, add miticide to oil according to the Pear Pest Management Guidelines.
Aphids
  • In cool springs, evaluate damage according to the Pear Pest Management Guidelines.
Pearslug
  • Spot treatments according to the Pear Pest Management Guidelines may be warranted for localized infestations.
Pearleaf blister mites
  • If present, plan to treat for this pest according to the Pear Pest Management Guidelines.
Katydids
  • Treatment may be necessary if foliage damage and nymphs are present on tree.

Fruit clusters

 Codling moth
  • If any eggs or larval entries are found, treat according to the Pear Pest Management Guidelines.
Obliquebanded leafroller
  • If more than two clusters out of 40 contain leafrollers, treat according to the Pear Pest Management Guidelines.
Pear rust mite
  • If two or more pears have rust mites or if any pear has more than 30 mites, treat according to the Pear Pest Management Guidelines.
Plant Bugs:
Consperse stink bug
  • If more than three fruit per 30 minute search show evidence of stink bug, treat according to the Pear Pest Management Guidelines.
Western boxelder bug
  • If bugs or damage are present, a spot treatment according to the Pear Pest Management Guidelines may be warranted.
Lygus bug
  • One damaged pear in 100 is cause for concern and calls for further sampling and evaluation of control need.

Important Links

Text Updated: 11/12
Feedback