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How to Manage Pests
UC Pest Management Guidelines
Apple
Fruittree
Leafroller
Scientific name: Archips
argyrospila
(Reviewed 8/06,
updated 8/06)
In this Guideline:
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Fruittree
leafroller overwinters in the egg stage in irregular masses of 30 to 100 eggs cemented over with a secretion.
Young larvae are light green caterpillars with black heads and are first seen
at bud break. The mature larva is about an inch long and has a green body and
black head. The black head helps distinguish fruittree leafroller from other
leafrollers. There is one generation per season.
The fruittree leafroller feeds principally on leaves, but also feeds
on blossoms, flower buds, and fruits during bloom. Tiny larvae work their way
into opening leaf buds to feed. Once the tree has leafed out, larvae tie up
leaves and live within leafrolls, feeding on leaves or fruit. Larvae damage
fruit in much the same way as green fruitworms, resulting in shallow cavities
in the fruit. Damaged fruits that remain on the tree develop deep bronze-colored scars with roughened,
netlike surfaces.
Generally fruittree leafrollers are the first caterpillars seen in
samples taken after green tip and have about 2 weeks to feed before the first
codling moth spray goes on. Young larvae are easiest to control because they
have not yet constructed a nest out of leaves, which protects them from
insecticides.
Biological Control
Natural enemies specific for fruittree leafroller are not known, but a
number of general predators, such as lacewing and
lady
beetle larvae,
and parasites feed on fruittree leafroller larvae. Although these natural
enemies help keep fruittree leafroller populations at low, nondamaging levels;
occasional outbreaks still occur, especially in the San Joaquin and inner
coastal valleys.
Organically Acceptable
Methods
Applications of approved narrow range oil, Bacillus thuringiensis,
and the Entrust formulation of spinosad are organically acceptable.
Monitoring
and Treatment Decisions
Fruittree leafroller usually is effectively controlled by a dormant oil
spray. Make an application thorough enough to cover egg masses. Check results
by sampling for leafrollers at green
tip.
Examine 100 fruit clusters per block. If no worms are found, resample in 1
week. If more than one worm is found, treatment before pink bud may
be necessary to prevent damage. Often infestations are usually confined to
small, localized areas of the orchard and can be spot treated.
| 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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| DELAYED DORMANT |
| A. |
NARROW RANGE OIL# |
6 gal |
2 gal |
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MODE OF ACTION: Contact including smothering and barrier effects. |
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COMMENTS: Check with certifier to determine which products are organically acceptable. |
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| B. |
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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| C. |
METHIDATHION* |
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(Supracide) 2EC |
3 qt |
1 qt |
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MODE OF ACTION: An
organophosphate (Group 1B)1 insecticide.
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| PINK BUD TO PETAL FALL |
| 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. 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: Apply 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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| 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 for it 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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