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Root Mealybugs

Arnold H. Hara,
CTAHR Dept. of Entomology, Hilo

Root mealybugs occur only on roots of their host plants. Because they are
undetected, occurring below-ground, root mealybugs can be a serious pest.
Currently, the Hawaiian Islands have 7 species of root or hypogaeic
mealybugs. The most pestiferous species have been the coffee root mealybug,
Geococcus coffeae, and Rhizoecus hibisci. Plant host range of these root
mealybugs are very wide, infesting grasses, palms, citrus, cyperus,
pineapple, coffee, mango and syngonium.

In pots, root mealybugs occur throughout the root mass; however, they are
concentrated between the root-ball and the pot. Infestations of root
mealybugs are noticeable only if the root-ball is removed from the pot. The
white waxy material is the most important sign of root mealybug infestation.
Mealybugs secrete lots of white waxy material that covers their bodies.
Female mealybugs lay eggs or give birth to live young (crawlers).If eggs are
laid, they usually hatch in less than 24 hours. Crawlers are the dispersal
stage and are highly mobile. Once the crawlers find a suitable site, they
settle down and begin to feed on roots with their sucking mouthparts. The
entire life cycle ranges from 2-4 months depending on the species. Adults
live from 27-57 days, also depending on species.

Prevention

Because the root mealybug is very difficult to control, every effort should
be made to prevent spread and establishment. The following practices are
recommended to prevent spread and establishment:

1.. Inspect roots of newly purchased plants for root mealybugs by removing
the pot.

2.. Avoid root-bound plants by re-potting as needed; root-bound plants
encourage mealybugs.

3.. Use clean pots and media; if infested wash with soap and water.

4.. Treat or remove infested plant hosts from your premises.

5.. Do not allow water from infested areas to drain into clean areas;
crawlers can be transported in water.


Control

Research by the University of Hawaii, CTAHR, has demonstrated that
insecticides and/or a hot water dip are effective treatments. Dursban WP
applied as a liquid drench and Marathon G are effective against root
mealybug. Watering plants prior to drench application will significantly
reduce problems with phytotoxicity. Consult the Cooperative Extension
Service, Hawaii Department of Agriculture or a reputable agrochemical
professional for a specific product registered for use. Submerging potted
Rhapis palms in 120° F (49° C) hot water until the internal root ball
temperature reaches 115° F(46° C) is 100% effective in killing root
mealybugs. Hot water at 120° F does not significantly affect potted
Rhapispalms.

For more information or a detailed report contact Arnold Hara in Hilo at
Ph: (808) 974-4105, Fax: (808) 974-4110 or e-mail: .


"Bob Walsh" wrote in message
...
I recently had an infestation of mites. I talked to Jerry Fischer at
Orchids
Ltd. and he said to use insecticidal soap three times three days apart on
all plants in the growing area. The problem seems greatly diminished, if
not
gone.

I will spray all the plants before bringing them in next fall.

Others have said just spraying mites with water is effective.
I like the soap. I want them dead.

Regarding the inside insects, put 3 quarts of water in a gallon container,
add one pint of alcohol and
one pint of orange 409. Spray weekly.

I was at an Orchid class recently and one of the speaker/vendors announced
that he had some plants with that he would no longer sell. He offered to
show all who wanted to see why. The plants were in clear plastic pots. He
had dropped one and when he picked it up and checked it for breakage he
noticed mealy bug larva on many of the roots. Sprays won't kill those.
unpotting, dipping and repotting will, but I wonder about the eggs.... Are
they laid topside or down around the roots as well?

Bob

"Minelli Family" wrote in message
...

"Dayton" wrote in message
...

Thanks. The biggest problem in spraying is that the plants are in a
closed room under flourescent and HID lights so ventilation is a real
problem during the winter (Maine where the low was -15° last week).
That's why I tried the Neem, it being a natural product. Will try some
of
the others, which I have all of for outdoor work, when I can open the
windows or take the plants outside. Was hoping that there might be a
magic bullet because the scale problem has been going on for a couple of
years. Every time I think they're gone, I turn around and they're back.


We have the same problem with meanly bugs and spider mites in a small
hobby greenhouse. No amount of spray, even systemic works for long. So
far the orchids have been spared, but we fear they'll get infested next.