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How to Manage Pests
UC Pest Management Guidelines
Apple
Orange Tortrix
Scientific name: Argyrotaenia franciscana (formerly A.
citrana)
(Reviewed 8/06,
updated 8/06)
In this Guideline:
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Orange tortrix, also called apple skinworm, is a pest in California coastal areas. The moths are
0.5 inch long with tan to rusty brown forewings. The 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 a silken thread.
Orange tortrix is an occasional pest in apple orchards. The principal damage caused
by orange tortrix larvae is feeding on the surface of fruit, where they leave shallow, irregular scars. Generally
they feed within a fruit cluster; occasionally they tie a leaf to the fruit's surface and feed under it.
Orange tortrix 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. Two parasitic wasps, Apanteles aristolilae and Exochus sp.,
are the most common. Hormius basalis, an external parasite, also occurs. Brown
lacewing, Hemerobius pacificus, is a general feeder on orange tortrix.
Cultural Control
Thin fruit to one or two fruit per cluster to reduce available habitat and to increase exposure of larvae to
parasites, predators, and insecticides. Remove and dispose of mummy fruit to reduce overwintering orange
tortrix. Orange tortrix feeds on many weeds found in orchards, such as mustard.
Plant low-growing grass cover crops to reduce overwintering hosts of orange tortrix.
Organically Acceptable Methods
While rarely a significant pest in organic orchards, biological and cultural controls and sprays of Bacillus
thuringiensis and the Entrust formulation of spinosad are organically acceptable methods for pest control.
Monitoring and Treatment Decisions
Usually orange tortrix does not appear in apple trees until June when eggs from the first summer generation
are laid. Sample trees for larvae once a month in June, July, and August; take the first sample no later
than mid-June. Examine 10 trees of each variety in each block for 4 minutes each. Each larva found, whether
orange tortrix, apple pandemis, or eyespotted bud moth. Correlates to about 1% fruit damage at harvest.
| Common name |
Amount to Use |
P.H.I.+ |
| (trade name) |
(conc.) |
(dilute) |
(days) |
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| When choosing a pesticide, consider information relating to the impact
on natural enemies and honey bees and environmental impact. |
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| A. |
BACILLUS THURINGIENSIS ssp. KURSTAKI# |
| |
(various products) |
Label rates |
— |
0 |
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MODE OF ACTION: A microbial (Group 11.B2)1 insecticide. |
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COMMENTS: Least harmful to beneficials. Bt is a stomach poison and must be consumed by the
leafroller; therefore it is most effective when applied during warm, dry weather when larvae are actively
feeding. Most effective against young larvae. Requires more than 1 treatment; apply second application
7–10 days after first. |
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| B. |
SPINOSAD |
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(Entrust)# |
2-3 oz |
0.5-0.75 oz |
7 |
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(Success) |
6–10 fl oz |
2–3.3 fl oz |
7 |
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MODE OF ACTION: A microbial (Group 5)1 insecticide. |
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COMMENTS: To prevent the development of resistance to this product, rotate to a material
with a different mode of action after treating two consecutive generations. 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 |
— |
14 |
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MODE OF ACTION: An insect growth regulator (Group 18)1 insecticide. |
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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 (must be ingested to be effective). For each generation, begin applications at early
egg hatch before webbing and sheltering begin. Make a second application in 10–14 days. 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: Apple
UC ANR Publication 3432
Insects and Mites
J. L. Caprile, UC Cooperative Extension, Contra Costa County
L. R. Wunderlich, UC Cooperative Extension, El Dorado County
P. M. Vossen, UC Cooperative Extension, Sonoma and Marin counties
W. W. Coates, UC Cooperative Extension, San Benito County
H. L. Andris, UC Cooperative Extension, Fresno County
L. G. Varela, UC IPM Program, Sonoma County
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to the insects and mites section:
C. Pickel, UC IPM Program, Sutter and Yuba counties
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