How to Manage Pests
UC Pest Management Guidelines
Dormant Shoot Sampling
In this Guideline:
shoot sampling is used to determine the need for a dormant treatment for the
control of San Jose scale, European fruit lecanium, and mite eggs (brown mite
and European red mite).
HOW TO SAMPLE (View photos for identification)
Take a sample between late November and mid-January.
Randomly select 20 trees from each varietal block in the
Choose 5 shoots randomly from the inside of each tree's
canopy near the main scaffolds for a total of 100 shoots.
Clip off a 3-inch section
from the basal portion of the shoot that contains
both 1- and 2-year old wood.
Using a hand lens or binocular microscope, examine the
section of the shoot and note the presence or absence of scales and parasitized
scales and mite eggs on a sampling
form . It is not necessary to
count the number of individual insects or mite eggs present, just identify the
pest and record whether it is present or not.
Note if scales have been parasitized. A
parasitized scale can be distinguished
from a live scale by a small hole in the tops of the scale covering. Parasitized
European fruit lecanium scales turn black. If
a large number of scales have been parasitized, minimize the use of insecticides
during the growing season, and use those that are not harmful to parasites so
that naturally occurring parasite populations will not be destroyed.
Use the Dormant Treatment Decision Table below to determine if
treatment is required and what to spray.
TREATMENT DECISION TABLE (% infested
|European fruit lecanium
||24% and below
|overwintering mite eggs
(brown mite and European red)
|20% and over
San Jose scale
||Harvested before June 15
||Harvested after June 15
||Oil at 6 gal/acre
||Oil at 2-6 gal/acre plus insect growth regulator1
Choice of Pesticides
pesticide depends on which pests are present at damaging levels and when
treatment is being applied. During the dormant season, oils alone are effective
against the white cap and black cap stages of San Jose scale, which are present
at this time, and will also control populations of mite eggs and provide
moderate control of fruittree leafroller eggs. Only the highest levels of San
Jose scale will require addition of an insect growth regulator. Other pests
such as peach twig borer and obliquebanded leafrollers will not be controlled
by oil during the dormant season. Environmentally sound insecticides such as Bacillus
(Altacor), diflubenzuron (Dimilin), and methoxyfenozide (Intrepid), however,
applied at bloom will control peach twig borer and leafrolling caterpillars.
Combining these bloomtime treatments along with a dormant oil application for
scales, mite eggs, and leafroller eggs is a good IPM strategy for many orchards.
Organophosphates applied during the dormant season for peach twig borer are particularly
vulnerable to run-off into waterways, are no more effective than reduced risk
products, and should be avoided. Never spray before an expected rainfall. If
you wish to treat peach twig borer during the dormant season, consider an environmentally
sound insecticide such as spinosad, spinetoram, or diflubenzuron. See the PEACH
TWIG BORER guideline.
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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