How to Manage Pests
UC Pest Management Guidelines
In this Guideline:
Preharvest fruit sampling will alert you to the
need to treat before harvest. (Be sure to check the preharvest interval of the
pesticide if treatment is necessary.) Monitor weekly beginning at color break
(when nectarines start to turn reddish).
How to Sample (view preharvest damage photos for identification)
Examine 100-200 randomly selected fresh fruit on
the tree (10–20 fruit on 10 trees) by looking at it on the tree and
rotating it slightly to detect damage caused by:
twig borer, oriental fruit moth, or larvae
San Jose scale, or parasitized San Jose Scale
bugs and plant bugs
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; be sure to keep a record for each block.
How to Sample (view harvest damage photos for identification)
the sorting process begins, examine 500 to 1,000 randomly selected fruit from
harvest containers. Plan to sample 500 fruit for each variety unless unexpected
damage is discovered, in which case increase the sample size up to a maximum of
1,000 fruit in order to thoroughly assess the damage. Distinguish damage caused
by peach twig borer, oriental fruit moth, and leafrollers, San Jose scale,
stink bugs, plant bugs, katydids, and thrips as well as brown rot, rust, and
Look for the presence of:
- Larvae or larval feeding
from peach twig borer, oriental fruit moth, or leafroller caterpillars.
- Peach twig borer : shallow feeding holes.
Over time these may appear as scabs.
- Oriental fruit moth : small entry holes that may
be difficult to see, especially if brown rot has invaded the site.
- Leafrollers: tunneling into
fruit; shallow holes or grooves in the fruit surface; this can sometimes be
difficult to distinguish from severe thrips feeding that was done just after
- Live or parasitized San Jose scale and halos or spots on the
- Scabs, pits caused by stink bugs, plant bugs, and katydids.
- Surface scarring caused by thrips feeding.
- Fruit rot. In many cases, this damage
may occur in conjunction with peach twig borer or oriental fruit moth damage or
other physical injury.
- Scab lesions on fruit are dark
spots and may have green or yellow halos. They are most commonly on the upper
surface and may merge to form large blotches.
- Rust lesions, which can resemble
stink bug damage but can be distinguished by the presence of spore masses in
the lesions, and lesions are often surrounded by halos.
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. Record the number of fruit with damage caused by
stink bugs, plant bugs, katydids, thrips, and note any indication of rust,
brown rot, and scab. Record results for harvest sample.
UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
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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