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How to Manage Pests
UC Pest Management Guidelines
Floriculture and Ornamental Nurseries
Foliar-Feeding Mealybugs
Scientific names: Citrus mealybug: Planococcus citri
Madeira mealybug: Phenacoccus madeirensis
Longtailed mealybug: Pseudococcus longispinus
(Reviewed 1/04,
updated 1/04)
In this Guideline:
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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.
BIOLOGICAL CONTROL
Cryptolaemus montrouzieri, the
mealybug destroyer lady beetle, is an
effective predator of citrus and Mexican 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.
MONITORING and WHEN TO TREAT
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' body 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.
| Class |
|
Pesticide (commercial name) |
Manufacturer |
R.E.I.1 |
Comments |
| biological |
A. |
Beauveria bassiana
(BotaniGard 22 WP)
(BotaniGard ES) |
Emerald BioAg. |
4
12
|
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/PBO2
(PT 1100 Pyrethrum TR) |
Whitmire
MicroGen |
12 |
An aerosol. |
|---|
| B. |
pyrethrin/rotenone
(Pyrellin EC) |
Webb Wright |
12 |
|
|---|
| insect growth regulator |
A. |
azadirachtin
(Azatin XL Plus) |
Olympic |
4 |
Must contact insect. Repeated applications as necessary. Only
effective on immatures. Label permits low-volume application. |
|---|
| B. |
azadirachtin
(Ornazin 3%EC) |
SePRO |
12 |
Do not exceed 22.5 oz/acre/application. |
|---|
| C. |
s-kinoprene
(Enstar II) |
Wellmark |
4 |
Apply prebloom. Only effective on immatures. Also labeled for
low volume use. Do not apply through any type of irrigation system. |
|---|
| neonicotinoid |
A. |
imidacloprid
(Marathon 1G)
(Marathon II) |
Olympic |
12 |
Not to be used more than once every 16 weeks. Alternate with
insecticides that have a different mode of action to prevent development of
resistance to neonicotinoids. Do not apply to soils that are water logged or
saturated. Do not apply to bedding plants intended to be used as food
crops. |
|---|
| B. |
imidacloprid
(Marathon 60 WP) |
Olympic |
12 |
As above. Apply only as a drench. |
|---|
| oil3 |
A. |
clarified hydrophobic extract of neem oil
(Triact 70) |
Certis
|
4 |
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. Do not use through any type of irrigation
system. |
|---|
| B. |
horticultural oil
Ultra-Fine Oil
SafTSide
JMS Stylet Oil |
Whitmire MicroGen
Brandt
JMS Farms |
4
4
4
|
Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions.
|
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| organophosphate |
A. |
acephate
(Address) |
Dow |
24 |
Do not use through any type of irrigation system. |
|---|
| B. |
acephate
(Orthene T, T&O Spray) 75 WP |
Valent |
24 |
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. Do not use through any type of
irrigation system. |
|---|
| C. |
acephate
(PT 1300 Orthene TR) |
Whitmire MicroGen |
24 |
An aerosol for greenhouse use only. |
|---|
| D. |
chlorpyrifos*
(PT DuraGuard ME) |
Whitmire
MicroGen |
24 |
|
|---|
organophosphate/
pyrethroid |
A. |
chloropyrifos/
cyfluthrin*
(PT Duraplex TR) |
Whitmire MicroGen |
24 |
An aerosol. |
|---|
| pyrethroid |
A. |
bifenthrin*
(Attain TR) |
Whitmire MicroGen |
12 |
A fogger for greenhouse use only. |
|---|
| B. |
bifenthrin*
(Talstar Flowable) |
FMC |
12 |
Label permits low-volume application. |
|---|
| C. |
cyfluthrin
(Decathlon 20 WP) |
Olympic |
12 |
Label permits low-volume application. Do not use through any
type of irrigation system. |
|---|
| D. |
deltamethrin*
(DeltaGard) |
Bayer |
12 |
Do not use through any type of irrigation system. |
|---|
| E. |
fenpropathrin*
(Tame 2.4 EC Spray) |
Valent |
24 |
Label permits low-volume application. Do not use through any
type of irrigation system. |
|---|
| F. |
fluvalinate
(Mavrik Aquaflow) |
Wellmark |
12 |
Label permits low-volume application. Also labeled as a cutting
dip at 5 fl oz/100 gal. Do not use through any type of irrigation system. |
|---|
| G. |
permethrin*
(Astro) |
FMC |
12 |
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. |
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UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Insects and Mites
K. L. Robb, UC Cooperative Extension, San Diego Co.
H. S. Costa, Entomology, UC Riverside
J. A. Bethke, Entomology, UC Riverside
M. P. Parrella, Entomology, UC Davis
Acknowledgment for contributions to the insects and mites section:
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
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