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How to Manage Pests
UC Pest Management Guidelines
Apple
Woolly
Apple Aphid
Scientific name: Eriosoma
lanigerum
(Reviewed 8/06,
updated 8/06)
In this Guideline:
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Woolly apple aphids infest roots, trunks, limbs, shoots, and
occasionally fruit of apple trees. The bodies of these bark-feeding aphids are
completely covered by masses of white, wool-like, waxy materials. This aphid is
found in colonies on the aerial portions of the tree and on roots during
winter. The nymphs migrate up or down the trunk of infested trees during summer
and fall.
The main injury to young and mature trees is stunting due to the
formation of root galls. If
populations are high, honeydew and sooty mold will also be problems, and aphids
may enter the calyx end of fruit.
Woolly apple aphid is found throughout California's apple-growing
regions, and it is a major pest in coastal counties. It occasionally infests
pyracantha, hawthorn, and pear.
Resistant
Varieties/Rootstocks
Winter Banana is one of the most susceptible varieties to aerial galls.
Yellow Newtown fruit frequently has aphids in the calyx end. The Malling series
of rootstock numbers 106 and 111 are resistant to this pest.
Biological Control
Aphelinus mali is a parasite that can
completely control aerial colonies. In the absence of this parasite there can
be large increases of aerial colonies and woolly aphids may be found in the
calyx of the apple. Outbreaks of woolly apple aphid are most common following
the use of pyrethroids, which destroys its natural enemies.
Organically Acceptable
Methods
Resistant varieties and rootstocks as well as biological control are
organically acceptable methods.
Treatment Decisions
The delayed dormant application should control woolly apple aphids. A
summer application (late July to August) will only be required if the parasites
are disrupted. Foliage treatments may be necessary for young trees with severe
infestations.
| 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 (Preferred timing)
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| A. |
NARROW RANGE OIL |
4–6 gal |
1–1.5 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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. . OR . . .
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DIAZINON* 50WP |
2–4 lb |
0.5–1.0 lb |
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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.
Diazinon has been found in surface waters at levels that violate federal and state water quality standards. |
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| FOLIAGE SPRAY |
| A. |
DIAZINON* 50WP |
4 lb |
1 lb |
21 |
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MODE
OF ACTION: An organophosphate (Group 1B)1 insecticide.
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COMMENTS:
Applications made during the foliage season are very disruptive to
beneficials. Avoid drift and runoff into surface waters or choose alternative materials. |
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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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