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How to Manage Pests

UC Pest Management Guidelines


Citrus mealybug colony.

Floriculture and Ornamental Nurseries

Foliar-Feeding Mealybugs

Scientific names:
Citrus mealybug: Planococcus citri
Madeira mealybug: Phenacoccus madeirensis
Longtailed mealybug: Pseudococcus longispinus

(Reviewed 3/09, updated 6/10)

In this Guideline:


DESCRIPTION OF THE PESTS

Mealybugs are slow-moving sucking insects that have a loose, waxy coating on the body, which gives them their "mealy" appearance. The citrus mealybug is heavily and evenly covered with white, powdery wax, except for a faint narrow streak down the middle. It has short, wax filaments along the sides and hind filaments that are about one-fourth as long as the body. Both the citrus mealybug and the Mexican mealybug lay eggs in ovisacs (eggs are within masses of cottony wax). The Mexican mealybug can be distinguished from the citrus mealybug by four rows of thinly waxed depressions down the back. The longtailed mealybug has four long terminal wax filaments, which it holds parallel to the axis of the body; it also gives birth to live young. Mealybug infestations often occur underneath foliage and in hidden areas within dense foliage.

DAMAGE

Mealybugs remove sap from plants, which can cause yellowing of leaves and decline in vigor. Mealybug ovisacs and excreted honeydew are unsightly. Honeydew supports the growth of black sooty mold fungi and attracts ants; ants may then carry mealybugs to uninfested plants and tend them for honeydew, as well as protect them from natural enemies.

MANAGEMENT

Biological Control
Cryptolaemus montrouzieri, the mealybug destroyer lady beetle, is an effective predator of many mealybugs and other ovisac-forming sucking insects (such as green shield scale). Larval mealybug destroyers themselves look like large, faster-moving mealybugs, but are readily distinguished by their chewing mouthparts. Leptomastix dactylopii, a parasite of citrus mealybugs, is also commercially available. Effective predators or parasites of longtailed mealybugs are not yet commercially available. For more information, see BIOLOGICAL CONTROL.

Monitoring and Treatment Decisions
Carefully inspect plants being brought in to start a new crop to ensure that they are free of mealybugs and other pests. If necessary, treat infested plants.

Regularly inspect plants for signs of honeydew (i.e., glistening, sticky leaves) and ant activity. Well-established infestations containing females with ovisacs are much more difficult to control with either systemic or contact insecticides than new infestations because reproducing adults usually stop feeding and the females' bodies or the wax secretions help protect eggs or crawlers.

TREATMENT

Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals
Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact.

Class   Pesticide
(commercial name)
Manufacturer R.E.I.1 Mode of action2 Comments

  Calculate impact of pesticide on air quality
biological A. Beauveria bassiana#
(BotaniGard 22 WP)
(BotaniGard ES)
Laverlam 4 Treat every 7 days while insects are active. Do not tank mix with most fungicides and wait 48 hours after application to apply a fungicide.
botanical A. pyrethrin/PBO3
(PT Pyrethrum TR)
Whitmire
MicroGen
12 3/— An aerosol.
B. pyrethrin/rotenone
(Pyrellin EC)
Webb Wright 12 3/21B  
insect growth regulator A. azadirachtin
(Azatin XL)
OHP 4 un Must contact insect. Repeat applications as necessary. Only effective on immatures. Label permits low-volume application.
B. azadirachtin
(Ornazin 3%EC)
SePRO 12 un Do not exceed 22.5 oz/acre/application.
C. s-kinoprene
(Enstar II)
Wellmark 4 7A Apply prebloom. Only effective on immatures. Also labeled for low volume use.
neonicotinoid A. acetamiprid
(TriStar) 70WSP
Cleary 12 4A Apply as a foliar spray.
B. dinotefuran
(Safari) 20G
Valent 12 4A Can be applied as a drench or foliar spray.
C. imidacloprid
(Marathon 1G)
(Marathon II)
OHP 12 4A Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops.
  (Marathon 60 WP)       As above. Apply only as a drench.
D. thiamethoxam
(Flagship) 25WG
Syngenta 12 4A Can be applied as a drench or foliar spray.
oil4 A. clarified hydrophobic extract of neem oil#
(Triact 70)
OHP

4 un Do not spray plants under stress. Target pest must be completely covered with spray. Check label for list of plants that can be treated. May cause injury to flowers.
B. horticultural oil5
(Ultra-Fine Oil)
(SafTSide)
(JMS Stylet Oil)

Whitmire
MicroGen
Brandt
JMS Farms

12
4
4




Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions.
organophosphate A. acephate
(Acephate 97UP)
United
Phosphorus
24 1B  
B. acephate
(Orthene T, T&O Spray)
Valent 24 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse, only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses.
C. acephate
(PT 1300 Orthene TR)
Whitmire MicroGen 24 1B An aerosol for greenhouse use only.
D. chlorpyrifos*
(PT DuraGuard ME)
Whitmire
MicroGen
24 1B  
organophosphate/
pyrethroid
A. chloropyrifos/
cyfluthrin*
(PT Duraplex TR)
Whitmire MicroGen 24 1B An aerosol.
pyrethroid A. bifenthrin
(Attain TR)
Whitmire MicroGen 12 3 A fogger for greenhouse use only.
B. bifenthrin*
(Talstar Professional)
FMC 12 3 Label permits low-volume application.
C. cyfluthrin
(Decathlon 20 WP)
OHP 12 3 Label permits low-volume application.
D. deltamethrin*
(DeltaGard)
Bayer 12 3  
E. fenpropathrin*
(Tame 2.4 EC Spray)
Valent 24 3 Label permits low-volume application.
F. fluvalinate
(Mavrik Aquaflow)
Wellmark 12 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal.
G. permethrin
(Astro)
FMC 12 3 Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, diffenbachia and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year.
1  Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing.
2 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
3 PBO = piperonyl butoxide.
4 Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs.
5 Check with certifier to determine which products are organically acceptable.
* Restricted use pesticide. Permit required for purchase or use.
# Acceptable for use on organically grown ornamentals.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Insects and Mites
J. A. Bethke, Entomology, UC Riverside
Acknowledgment for contributions to Insects and Mites:
K. L. Robb, UC Cooperative Extension, San Diego County
H. S. Costa, Entomology, UC Riverside
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
M. P. Parrella, Entomology, UC Davis

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