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How to Manage Pests
UC Pest Management Guidelines
Pear
California Pear Sawfly
Scientific name: Pristiphora abbreviata
(Reviewed 2/07,
updated 3/8)
In this Guideline:
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California
pear sawflies overwinter as pupae in the soil. In early spring, adults emerge and lay eggs, which usually
hatch by petal fall. Larvae are about the same green color as the leaves and
are difficult to see because they rest inside the edges of the feeding area.
Sawfly larvae can be distinguished from moth larvae by their spherical head
capsule; moth larvae have flattened head capsules. Maturing larvae are about
0.5 inch long. There is only one generation per year and larvae are present in
trees during spring months only. The California pear sawfly can be
distinguished from the pear sawfly (i.e., the pear slug) by the lack of a slimy
coating covering its body.
These pests are foliage feeders and do not attack fruit. Most eggs
hatch by petal fall and larvae immediately begin feeding on leaf tissue in a
circular pattern within or along leaf edges, leaving round or oval holes.
Several larvae can consume an entire leaf, leaving only the midrib. In heavy
numbers sawflies are capable of defoliating orchards in several weeks, but this
rarely occurs in California.
The California pear sawfly is distributed throughout pear-growing
regions in the state but is a minor pest of pears. Generally it only affects
backyard trees or commercial trees where treatment was not applied during the
bloom period. Treat only if justified by monitoring results.
Monitoring
and Treatment Decisions
Inspect foliage for small holes at petal fall or shortly after. Randomly sample
one leaf on each of 100 trees in a block. If there are less than six infested
leaves per block, no action is necessary. If 6 to 24 leaves are found infested,
monitor the infestation weekly for further increases in numbers and damage.
When 25 or more of the sampled leaves are infested, either advance the first
codling moth cover spray or apply a treatment aimed at this pest.
| Common name |
Amount to Use** |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
(conc.) |
(dilute) |
(hours) |
(days) |
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| When choosing a
pesticide, consider information relating to impact
on natural enemies and honey bees
and environmental impact.
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| A. |
SPINOSAD |
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(Entrust)# |
2-3 oz |
0.5-0.75 oz |
4 |
7 |
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(Success) |
6-10 fl oz |
2-3.3 fl oz |
4 |
7 |
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MODE OF ACTION GROUP
NUMBER1: 5
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COMMENTS: To prevent
the development of resistance to this product, rotate to a material with a
different mode of action Group number after treating two consecutive
generations. Do not apply more than 9 oz/acre/crop of Entrust or 29 fl oz of Success/acre/crop. |
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UC IPM Pest Management Guidelines: Pear
UC ANR Publication 3455
Insects and Mites
L. G. Varela, UC IPM Program, UC Cooperative Extension Sonoma Co.
R. B. Elkins, UC Cooperative Extension Lake Co.
R. A. Van Steenwyk, Insect Biology, UC Berkeley
C. Ingels, UC Cooperative Extension Sacramento Co.
Acknowledgment for contributions to the insects and mites section:
C. Pickel, UC IPM Program, UC Cooperative Extension Sutter/Yuba counties
P. W. Weddle, Weddle, Hansen & Associates
P. Chevalier, United Ag Products, Ukiah; B. Knispel, United Ag Products, Kelseyville
T. Lidyoff, Purity Products, Healdsburg; G. McCosker, AgroTech, Kelseyville
B. Oldham, Ag Unlimited, Ukiah
D. Smith, Western Farm Service, Walnut Grove
J. Sisevich, AgroTech, Kelseyville
B. Zoller, The Pear Doctor, Inc., Kelseyville
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