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How to Manage Pests
UC Pest Management Guidelines
Citrus
Mealybugs
Scientific Names:
Citrus mealybug: Planococcus citri
Citrophilus mealybug: Pseudococcus calceolariae
Longtailed mealybug: Pseudococcus longispinus
Comstock mealybug: Pseudococcus comstocki
(Reviewed 9/08,
updated 9/08)
In this Guideline:
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Mealybugs are soft, oval, flat, distinctly segmented, and covered
with a white, mealy wax that extends into spines (filaments) along the body
margin and the posterior end. The species differ mainly in the thickness and
length of the waxy filaments. Citrus mealybug, the most common species,
has a pinkish body that is visible through the powdery wax. The filaments
around its margins are not appreciably longer at the posterior end. The Comstock mealybug primarily occurs on lemons in the San Joaquin Valley and has a thicker wax
cover than the citrus mealybug. In addition, it has two spines at the posterior
end, about one-quarter the length of the body. The other two mealybug species
are usually not a problem in citrus because they are kept at low population
levels by parasites.
Female mealybugs lay
several hundred eggs on the leaves, fruit, or twigs; eggs for some of the species are laid in
cottony egg sacs. Newly hatched nymphs are light yellow and free of wax, but
soon start to excrete a waxy cover. There are two to three overlapping
generation a year. Mealybugs are often found between clusters of grapefruit,
especially in groves tended by ants.
Mealybugs extract plant sap, reducing tree vigor, and excrete
honeydew, which gets on plant surfaces and provides a surface upon which sooty
mold grows. If a cluster of mealybugs feeds along a fruit stem, fruit drop can occur. Damage is most severe in spring and fall.
Mealybugs are primarily managed by conserving their natural enemies
and reducing ant populations and dust problems. Treatment is rarely required.
Biological Control
Parasites provide good control of the citrophilus, longtailed,
and Comstock mealybugs if they are not destroyed by treatments for other pests.
Native predators include lady beetles, lacewings,
and syrphid
flies. An introduced
predator of the citrus mealybug, the mealybug destroyer,
Cryptolaemus montrouzieri, is a voracious feeder of the
pest in both the larval and adults stages. Its larvae resemble a mealybug but
are about twice as large as the adult citrus mealybug females. The adult is a
small beetle with dark brown wing covers and a light brown head and prothoraic
shield. Because Cryptolaemus does not
survive the winter well, it can be purchased from commercial insectaries in
early spring and released in orchards where citrus mealybugs were a problem the
previous year. Release about 500 Cryptolaemus per acre.
Organically Acceptable Methods
Biological control, including the release of Cryptolaemus
montrouzieri, is acceptable in organically managed citrus groves.
Monitoring
and Treatment Decisions
If a heavy population of mealybugs must be reduced quickly, a
treatment can be applied, but release Cryptolaemus about 2 weeks
after to reestablish biological control.
| Common name |
Amount to Use |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
(type of coverage) |
(hours) |
(days) |
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| The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used. |
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| A. |
CRYPTOLAEMUS MONTROUZIERI# |
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(Mealybug destroyer) |
500/acre |
NA |
NA |
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RANGE OF ACTIVITY: Pests: narrow (mealybugs); Natural enemies: none |
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PERSISTENCE: Pests: intermediate, does not survive winters well; Natural enemies: none |
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COMMENTS: Release in
early spring in orchards where citrus mealybugs were a problem the previous year. |
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| B. |
CHLORPYRIFOS* |
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(Lorsban) 4E |
0.75 pt/100 gal (TC) |
5 days |
see comments |
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RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most |
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PERSISTENCE: Pests: short
(low rates), intermediate (high rates); Natural enemies: short (low rates), intermediate (high rates) |
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MODE OF ACTION GROUP
NUMBER1: 1B |
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COMMENTS: For use on all
varieties. Do not apply during bloom or make second application within 30
days; do not exceed 2 applications or 12 pt/acre/year. Preharvest interval is 21 days up to 7 pt/acre and 35 days above 7 pt/acre. |
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. . . PLUS . . . (optional) |
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NARROW RANGE OIL |
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(415) |
1.2–1.4% |
4 |
when dry |
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RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects/mites); Natural enemies: most |
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PERSISTENCE: Pests: short; Natural enemies: short |
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MODE OF ACTION: Contact including smothering and barrier effects. |
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COMMENTS: Use highest
dosage of oil for July or Aug. applications. Caution: Serious
hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval. |
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UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Insects, Mites, and Snails
E. E. Grafton-Cardwell, Kearney Agricultural Center, Parlier
J. G. Morse, Entomology, UC Riverside
N. V. O‘Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
C. E. Kallsen, UC Cooperative Extension, Kern County
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgments for contributions to Insect, Mites, and Snails:
J. Barcinas, E. S. I., Corona, CA
R. Dunn, Badger Farming County, Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
H. Griffiths, E. S. I., Corona, CA
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
T. Roberts, E. S. I., Corona, CA
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA
K. Godfrey, USDA Biological Control, Sacramento
D. Headrick, California Polytechnic State University, San Luis Obispo
B. Faber, UC Cooperative Extension, Ventura County
J. Kabashima, UC Cooperative Extension, South Coast Research and Extension Center
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