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How to Manage Pests
UC Pest Management Guidelines
Pear
Orange Tortrix
Scientific name: Argyrotaenia
franciscana (= A. citrana)
(Reviewed 2/07,
updated 3/8)
In this Guideline:
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Orange tortrix, also called apple skinworm, is an occasional pest of
pears in California. Moths are
0.5 inch long with tan to rusty brown forewings. Fully grown larvae are about
0.5 inch long, straw-colored to green, with light brown heads. They are active
and quickly wiggle backwards when disturbed, dropping to the ground or spinning
down on a silken thread.
Not a major pest of pears, the principal damage caused by orange tortrix larvae is feeding on the surface of fruit, where they
leave shallow, irregular scars. Generally the larvae feed within a cluster of
fruit; occasionally they tie a leaf to the fruit's surface and feed under it.
A minor pest of pears, orange tortrix occurs in mostly coastal areas
and is frequently controlled by parasites, especially in warm years when high
temperatures slow its development. In cool years, higher populations occur, and
natural enemies may not be able to hold populations below economically damaging
levels; additional control measures may be needed.
Biological Control
Several parasites and predators attack
orange tortrix. Normally these natural enemies keep orange tortrix under control.
When these beneficials are disrupted by pesticide treatments, however, orange
tortrix may become an occasional pest. Two parasitic wasps, Apanteles
aristolilae and Exochus sp., are the most common naturally occurring
enemies. Hormius basalis, an
external parasite, also attacks orange tortrix. Brown lacewing, Hemerobius pacificus, is a general predator of orange tortrix.
Cultural Control
Because it is present in orchards all year
long, orange tortrix feeds on many of the winter weeds that grow in orchards,
such as mustard.
Plant low-growing grass cover crops to reduce overwintering hosts of orange
tortrix.
Organically Acceptable Methods
Biological and cultural controls and
sprays of Bacillus thuringiensis and Entrust formulation of
spinosad are organically acceptable methods.
Monitoring and Treatment Decisions
Usually orange tortrix does not appear
in pear trees until June when eggs from the first summer generation are laid.
Sample trees for larvae once a month in June and July (see SAMPLING
DURING FRUIT DEVELOPMENT). Take the first sample no later than mid-June.
Continue monitoring in combination with other pests. Treat if between 1 and 2%
damage occurs on fresh market pears (check with cannery fieldman for damage
acceptable for processing fruit).
| Common name |
Amount to Use** |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
(conc.) |
(dilute) |
(hours) |
(days) |
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| The following materials are listed in order of
usefulness in an IPM program, taking into account efficacy and impact on natural enemies
and honey bees. When choosing a pesticide, also
consider information relating to environmental impact.
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| NOTE: Various
pyrethroids are also registered for orange tortrix control in California, but
are not recommended because they can cause severe mite problems and are not cost effective for control of orange tortrix. |
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| A. |
BACILLUS THURINGIENSIS ssp. KURSTAKI# |
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(various products) |
Label rates |
— |
4 |
0 |
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MODE OF ACTION GROUP NUMBER1: 11.B2 |
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COMMENTS: Least harmful to beneficials. Bt is a stomach poison
and must be consumed by the leafroller. Must be applied when worms are small.
A second or third treatment may be required. Most effective if applied when
weather forecasts predict 3 to 4 days of warm, dry weather. Larvae are more active and feed more in warm weather than in cooler or rainy weather. |
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| B. |
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: Do not apply more than 3 sprays/season directed at
leafrollers. Do not apply more than 9 oz/acre/crop of Entrust or 29 fl oz of Success/acre/crop. |
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| C. |
METHOXYFENOZIDE |
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(Intrepid) 2F |
16 fl oz |
— |
4 |
14 |
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MODE OF ACTION GROUP NUMBER1: 18A |
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COMMENTS: Functions both as an ovicide (when applied to eggs
and when eggs are laid on residues) and as a larvicide. (larvae must ingest
it for it to be effective). Treat at early egg hatch before webbing and
sheltering begin. Spray coverage is extremely important. Ground application
should use 200 gal water/acre with a sprayer speed of 1.5 mph. The addition of a spray adjuvant is recommended to enhance spray coverage. |
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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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