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Why Is the Dormant/Delayed-Dormant Season Important in an IPM Program?

Dormant shoot of reproductive growth of peach.
Dormant shoot
Bud swell stage of peach bloom.
Bud swell
Green tip stage of peach bloom.
Green tip

The dormant season is a critical period for various pest management activities:

  • Several key insect and mite pests overwinter in orchards and are vulnerable to sprays.
  • Because leaves are off the tree, good spray coverage is easier to obtain.
  • Beneficial insects and mites are less affected by sprays during dormancy.
  • Several pests are concentrated on the twigs and shoots, making dormant season an excellent time for monitoring and assessing their populations.

Dormancy is generally defined as the period from leaf fall until growth resumes in spring. Delayed dormancy is the period from the resumption of growth, indicated by bud swell until green tip.

Dormant versus delayed-dormant treatments. If the main target is San Jose scale, then a dormant timing (before bud swell) for treatment is usually best. Control of European fruit lecanium nymphs, peach silver mite, peach twig borer larvae in hibernacula, and fruittree leafroller egg masses is effective at either timing. European red mites (eggs), brown mites (eggs), and obliquebanded leafroller larvae are best controlled using delayed-dormant timing.

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

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