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How to Manage Pests

UC Pest Management Guidelines

Larva of peach twig borer.


Early Season Monitoring

(Reviewed 6/10, updated 6/10)

In this Guideline:

Monitor the orchard early in the season as trees come into bloom to help detect potential pest problems early.

1. Monitor the orchard for plant bug and stink bug (view photos).

2. Monitor trees for the presence of peach twig borers, fruittree leafrollers, or obliquebanded leafrollers, katydids, and western flower thrips (view photos). Examine flowers and leaves on 2- to 3-year-old branches located at head height on each of 50 trees as you walk through each varietal block.

  • For peach twig borers and leafrollers, pull off a few flowers and examine for feeding, holes, or the presence of caterpillars.
  • For katydids, spend about 30 seconds examining leaves for feeding damage.
  • For thrips, examine blossoms from each tree by slapping a shoot with five to ten blossoms against a yellow card or look for the immature stages within the blossoms.

Montoring at this time will let you know the effectiveness of the dormant or bloom treatment and alert you to the need for additional treatment.

Pest What to look for Treatment threshold
katydids Katydid feeding consists of small holes in the center of young leaves. If any of the leaves examined show signs of feeding, treat.
western flower thrips Thrips in the blossoms. If a single immature thrips is found, treat.
. . . or . . .
If two blossoms out of 50 sampled have adult thrips, treat.
peach twig borer larvae At this time peach twig borers feed at the base of flowers where they bore into the calyx, creating small holes. They may also enter the tips of shoots causing them to wilt (see SHOOT STRIKE MONITORING). If any are present, a treatment is necessary at first flight.
fruittree leafroller, obliquebanded leafroller Fruittree leafroller and obliquebanded leafrollers feed on blossoms as well as young foliage and begin to tie leaves together. Thresholds have not been determined.



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
General Information
W. J. Bentley (Crop Team Leader), UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
R. A. Duncan, UC Cooperative Extension Stanislaus County
S. Johnson, Pomology, Kearney Agricultural Center, Parlier
J. A. Roncoroni, UC Cooperative Extension, Napa County

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