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How to Manage Pests
UC Pest Management Guidelines
Apple
Obliquebanded
Leafroller
Scientific name: Choristoneura
rosaceana
(Reviewed 8/06,
updated 8/06)
In this Guideline:
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Obliquebanded
leafroller overwinter as third instar larvae under bud scales. Larvae are yellowish green with
brown to black heads. As they mature, larvae construct tubular shelters from a
single leaf. There are two generations a year. Periodically, localized
infestations of obliquebanded leafroller occur and the larvae of the summer
generation can cause serious damage in July and August. Obliquebanded
leafroller is rarely a pest in Central Coast orchards.
Larvae feed on flower parts and on fruit early in the season,
causing deep depressions that eventually become rough and russeted by harvest.
Damage from the summer generation is usually more serious and results in superficial
skin tunnels or small holes near the stem portion of the fruit.
Obliquebanded leafroller can occur in orchards in spring and summer.
Summer damage is most commonly seen in orchards where a switch is made to the
use of highly selective materials (including mating disruption) against codling
moth that do not control obliquebanded leafrollers.
Biological Control
The parasitic wasp Macrocentrus iridescens
has been observed attacking obliquebanded leafroller larvae in the Central
Valley and in Central Coast and North Coast apple orchards.
Organically Acceptable
Methods
Sprays of Bacillus thuringiensis and the Entrust
formulation of spinosad are organically acceptable.
Monitoring and Treatment
Decisions
The best time to treat obliquebanded leafrollers is in spring, around
pink bud, before the larvae are sheltered under leaves and between fruit
clusters. Apply materials before bees are placed in orchards or after they are
removed. Control overwintering larvae with either a delayed dormant application
of oil and insecticide or a bloom
application. If orchards have experienced damage from this pest in previous
years or if leafrollers were observed in spring, also monitor the summer
generation. Take fruit and leaf cluster samples at pink bud and in July and
August. Tentative thresholds are two or more live larvae in a 100 fruit cluster
sample in spring, and four or more in summer.
| Common name |
Amount to Use |
P.H.I.+ |
| (trade name) |
(conc.) |
(dilute) |
(days) |
|
| When choosing a
pesticide, consider information relating to the impact
on natural enemies and honey bees and environmental impact.
|
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| DELAYED DORMANT |
| A. |
NARROW RANGE OIL |
4 gal |
1.5 gal |
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MODE OF ACTION: Contact including smothering and barrier effects. |
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.
. . PLUS . . .
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CHLORPYRIFOS* |
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(Lorsban) 4EC |
Label rates |
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MODE
OF ACTION: An organophosphate (Group 1B)1 insecticide.
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COMMENTS:
Avoid drift and runoff into surface waters or choose alternative materials.
Chlorpyrifos has been found in surface waters at levels that violate federal and state water quality standards. |
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| BLOOM |
| A. |
SPINOSAD |
| |
(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: Most
effective when applied at petal fall. 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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| B. |
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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| 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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