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How to Manage Pests
UC Pest Management Guidelines
Apple
Green
Fruitworms
Scientific name:
Speckled green fruitworm: Orthosia hibisci
Humped green fruitworm: Amphipyra pyramidoides
(Reviewed 8/06,
updated 8/06)
In this Guideline:
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Immature larvae of both species are light green caterpillars. Mature
green fruitworms have green bodies and green heads. Speckled green fruitworms
have cream-colored lines down the back and sides of the body. Humped green
fruitworms are distinguished by a prominent hump on the last segment, bright
yellow lines on the side, and less distinct white lines on the back. They have
only one generation a year. Egg hatch extends from pink bud to
after petal fall.
Young green fruitworm larvae feed on leaves. Fruit feeding usually begins about petal fall and continues until larvae have completed their
development. At harvest, these fruit are misshapen and have large, roughened,
russeted cavities.
Green fruitworm populations in an orchard are usually spotty; often
they occur near borders where windbreaks and other trees serve as sources of
infestation. Delayed dormant treatments containing organophosphates applied for
other pests may control green fruitworms. In orchards where a delayed dormant
spray was not applied, green fruitworms can become a problem. Monitor to
determine need for treatment.
Organically Acceptable Methods
Sprays of Bacillus
thuringiensis and the Entrust formulation of spinosad are
organically acceptable.
Monitoring and Treatment
Decisions
Because
populations of green fruitworm are often spotty within an orchard, thoroughly
sample each block. Three sampling methods may be used: (1) Inspect 100 fruit
clusters for presence of worms; (2) Take 50 beating-tray samples, especially
around petal fall when larvae are easy to dislodge; (3) Inspect a block for a
half hour looking for damaged foliage and clusters. When one or more larvae per
100 clusters or 50 beating tray samples are found, treatment may be necessary.
| 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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| 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: Apply at bloom or petal fall.
Least harmful to beneficials. Bt is a stomach poison and must be consumed by
the caterpillar; 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 oz |
2–3.3 oz |
7 |
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MODE OF ACTION: A microbial (Group 5)1
insecticide.
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COMMENTS: Apply at pink bud or petal fall
when monitoring indicates larvae are present. 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. |
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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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| D. |
AZINPHOSMETHYL* |
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(Guthion) 50WP |
1 lb |
0.25 lb |
14 |
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MODE OF ACTION: An organophosphate (Group
1B)1 insecticide.
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COMMENTS: Apply at petal fall. Check the label for restricted entry intervals, which vary according to activity. |
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| E. |
DIAZINON* 50WP |
2 lb |
0.5 lb |
21 |
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MODE OF ACTION: An organophosphate (Group
1B)1 insecticide.
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COMMENTS: Apply during delayed dormancy or at petal fall. Avoid drift and tailwater runoff into surface waters. |
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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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