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How to Manage Pests
UC Pest Management Guidelines
Peach
Obliquebanded Leafroller
Scientific name: Choristoneura rosaceana
(Reviewed 3/06,
updated 3/06)
In this Guideline:
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Obliquebanded
leafroller overwinter as third-instar larvae under bud scales. The overwintered larvae
pupate in spring, and the first generation of adults emerges in late April or
May. Larvae are
yellowish green with brown to black heads. As they mature, larvae construct
tubular shelters from a single leaf. Adults are
reddish brown moths with dark brown bands on the wings. There are usually two
generations a year in the Sacramento Valley and up to three in the San Joaquin
Valley.
Infestations of obliquebanded leafroller can occasionally reach
damaging levels in peaches. Larvae feed on flower parts and on fruit early in
the season, causing deep
depressions that eventually become rough and russeted by harvest. Because of the high
cyanide content of peach leaves, larvae generally concentrate their feeding on
fruit; consequently, lower numbers of larvae may cause more damage in peaches
than in other crops. This leafroller is more damaging than fruittree
leafrollers because it has one to two summer generations.
Delayed dormant treatments and bloom time applications for other pests
help keep leafroller populations under control. However, regular monitoring
each season is important so that prompt action can be taken if damaging
populations develop. Throughout the season, watch for the presence of
leafrollers while monitoring for other pests. This is especially important in
orchards where bloom time sprays and pheromone confusion are used to control
peach twig borer and oriental fruit moth.
Biological Control
A number of parasites, including species of Macrocentrus, Cotesia (=Apanteles), and Exochus, attack
leafroller larvae. General predators such as lacewings,
assassin bugs,
and minute
pirate bugs may feed on eggs and larvae. Preservation of natural enemy populations is an
important part of keeping leafroller numbers low. Use selective materials that
are least disruptive of biological control when treating other pests.
Organically
Acceptable Methods
Organically acceptable management tools include biological control and
sprays of Bacillus thuringiensis or the Entrust formulation of
spinosad.
Monitoring
and Treatment Decisions Degree-day
calculator Degree-day table
Check the orchard in early spring (March–April) for the presence of
larvae and feeding damage on flowers (see EARLY SEASON MONITORING). If damaging populations are observed, a
number of environmentally friendly insecticides are effective in controlling
this pest, including Bacillus thuringiensis, spinosad
(Entrust, Success), and methoxyfenozide (Intrepid). The best timing for control
of overwintering larvae is at full bloom or early petal fall.
Pheromone
traps placed in the orchard in mid-April (see PHEROMONE TRAPS) will help to monitor the population levels of
this insect and provide information for management of the summer generations.
Based on research done in California pistachio orchards, begin accumulating
degree-days as soon as traps begin to catch moths using a lower threshold of
43°F and an upper threshold of 94°F. (For assistance in calculating
degree-days, see "Degree-days"). Make treatments between 600 and 1000 DD.
Take fruit samples every
other week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the
orchard and 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
(see FRUIT EVALUATION AT HARVEST). Record results
on monitoring forms for preharvest and harvest samples.
| Common name |
Amount to Use** |
P.H.I.+ |
| (trade name) |
(conc.) |
(dilute) |
(days) |
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| The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, impact on natural enemies and honey bees, and impact of the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact.
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| DELAYED DORMANT |
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| A. |
NARROW RANGE OIL |
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(Superior, Supreme) |
4–8 gal |
1.5–2 gal |
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MODE OF ACTION: Contact including smothering and barrier effects. |
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. . . PLUS . . . |
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SPINOSAD |
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(Entrust)# |
1.25–2.5 oz |
0.3–0.6 oz |
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(Success) |
4–8 oz |
1–2 oz |
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MODE
OF ACTION: A microbial (Group 5)1 insecticide.
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| BLOOM |
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| A. |
BACILLUS THURINGIENSIS ssp. KURSTAKI#
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(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)# |
1.71–2.5 oz |
0.43–0.6 oz |
14 |
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(Success) |
6–8 oz |
1.5–2 oz |
14 |
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MODE
OF ACTION: A microbial (Group 5)1 insecticide.
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COMMENTS: Most
affective when applied at petal fall. This product is toxic to bees for 3
hours following treatment; apply in the late evening after bees have stopped
foraging. Do not apply more than 29 oz/acre/year of Success or 9 oz/acre/year of Entrust. |
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| C. |
METHOXYFENOZIDE |
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(Intrepid) 2F |
8-16 oz |
2-4 oz |
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MODE OF ACTION: An
insect growth regulator (Group 18)1 insecticide.
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COMMENTS: Apply at
petal fall. Do not apply more than 16 fl oz/acre/application or 64 fl oz/acre/season. |
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| D. |
DIFLUBENZURON* |
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(Dimilin) 2L |
12 oz |
3 oz |
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MODE OF ACTION: An
insect growth regulator (Group 15)1 insecticide.
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COMMENTS: Include vegetable oil at the
rate of 1 qt/acre. Do not apply after petal fall. Do not exceed 2 applications in any given season. Allow 21 days between applications. |
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| AFTER BLOOM |
|
| A. |
BACILLUS THURINGIENSIS ssp. KURSTAKI#
|
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(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)# |
1.71–2.5 oz |
0.43–0.6 oz |
14 |
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(Success) |
6–8 oz |
1.5–2 oz |
14 |
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MODE
OF ACTION: A microbial (Group 5)1 insecticide.
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COMMENTS: This
product is toxic to bees for 3 hours following treatment; apply in the late
evening after bees have stopped foraging. Do not apply more than 29 oz/acre/year of Success or 9 oz/acre/year of Entrust. |
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| C. |
METHOXYFENOZIDE |
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(Intrepid) 2F |
8-16 oz |
2-4 oz |
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MODE OF ACTION: An
insect growth regulator (Group 18)1 insecticide.
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COMMENTS: Do not apply more than 16 fl oz/acre/application or 64 fl oz/acre/season. |
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| D. |
CARBARYL* |
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(Sevin) 80S |
5 lb |
1.25 lb |
1 |
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MODE
OF ACTION: A carbamate (Group 1A)1 insecticide.
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COMMENTS: May cause
increased spider mite problems; best used late in the season. Do not apply more than 7.5 lb/acre/season. |
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| E. |
PHOSMET |
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(Imidan) 70WP |
4.25 lb |
1 lb |
14 |
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MODE
OF ACTION: An organophosphate (Group 1B)1 insecticide.
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UC IPM Pest Management Guidelines: Peach
UC ANR Publication 3454
Insects and Mites
C. Pickel, UC IPM Program, Sutter/Yuba counties
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
J. K. Hasey, UC Cooperative Extension, Sutter/Yuba counties
K. R. Day, UC Cooperative Extension, Tulare Co.
Acknowledgment for contributions to the insects and mites section:
R. E. Rice, Kearney Agricultural Center, Parlier
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