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Group Title: Bradenton GCREC research report - University of Florida Gulf Coast Research and Education Center ; BRA1989-9
Title: Successful management of sweet potato whitefly in commercial flower production
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Permanent Link: http://ufdc.ufl.edu/UF00065233/00001
 Material Information
Title: Successful management of sweet potato whitefly in commercial flower production
Series Title: Bradenton GCREC research report
Physical Description: 5 p. : ; 28 cm.
Language: English
Creator: Price, J. F ( James Felix )
Schuster, David J
Kring, James B. ( James Burton ), 1921-
Gulf Coast Research and Education Center (Bradenton, Fla.)
Publisher: Gulf Coast Research and Education Center, IFAS, University of Florida
Place of Publication: Bradenton FL
Publication Date: 1989
 Subjects
Subject: Sweetpotato whitefly -- Control -- Florida   ( lcsh )
Flowers -- Diseases and pests -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 4).
Statement of Responsibility: James F. Price, David J. Schuster and James B. Kring.
General Note: Caption title.
General Note: "July, 1989"
 Record Information
Bibliographic ID: UF00065233
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 63760467

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida




60


9CtOce

GULF COAST RESEARCH AND EDUCATION CENTER
IFAS, UNIVERSITY OF FLORIDA I 189
5007 60th Street East
Bradenton, FL 34203 Univ8Fiy fi forida

Bradenton GCREC Research Report BRA1989-9 JuT -1989

SUCCESSFUL MANAGEMENT OF SWEETPOTATO WHITEFLY IN
COMMERCIAL FLOWER PRODUCTION

James F. Price, David J. Schuster and James B. Kring~

INTRODUCTION

Sweetpotato whitefly began to menace Florida's flower industries in 1986
(Hamon and Salguero 1987, Price et al. 1987). Heavy losses occurred
during that first year. The sweetpotato whitefly now is present
throughout most of the year and threatens ornamentals in all parts of
Florida.. This article provides the basic information necessary to
understand sweetpotato whitefly management and provides specific steps to
achieve control.

Distribution

Only plants grown in tropical and subtropical regions were infested (Cock
1986) until sweetpotato whiteflies became established in greenhouse
ornamentals, where entire plants are moved among regions. When infested
plants arrive in temperate regions climatically unsuitable for the
sweetpotato whitefly, plants are often placed in greenhouses with suitable
climates. Movement of plant material within a newly infested region
further distributes the insect. The sweetpotato whitefly is found
throughout the tropical world and now is found in greenhouses in North
America, Europe and other temperate areas.

Damage

Sweetpotato whitefly is important to the ornamentals industry because of
the large number of crops it affects, the damage it causes to those crops,
and the human reaction to possible infestations. All living whitefly
stages and dead immature forms stay on leaves when the crop is sold.
Customers object to the appearance of plants with sweetpotato whiteflies.
Regulatory officials also object to the potential of insects infesting a
new location. The nymphal and adult stages of the whitefly produce
honeydews upon which sooty molds grow and also affect the appearance of
ornamental plants. In addition, whiteflies feeding on the foliage can
affect the color and growth of the plants.


1Associate Professor of Entomology, Professor of Entomology, and Adjunct
Professor, respectively.











Important flower crops on which the sweetpotato whitefly causes serious
damage, include poinsettia, gerbera daisy and hibiscus. Greathead (1986)
listed 506 host plants and many are ornamentals.

Sweetpotato whiteflies are capable of transmitting certain viruses to
plants. Fortunately, at the present time no viruses important to
ornamental production are known to be transmitted. As the sweetpotato
whitefly and ornamental crops remain together, this may change.

Biology and Appearance

Adult sweetpotato whiteflies occur on the undersides of host leaves. They
feed on plant juices with their piercing and sucking mouth parts. The
adult whiteflies are white, narrow and less than 1/16 inch long. Females
lay about 6-12 eggs per day on poinsettia leaves during the daylight hours
(Janssen and Price, unpublished data). The eggs are laid singly or in
small groups on the undersides of leaves. They are cigar shaped, placed
on end, are creamy white when young, turn light brown in about a day and
hatch after one week. A first stage nymph, sometimes called a crawler,
emerges from the egg, moves less than 1/8 inch and attaches itself to the
lower surface of the leaf where the nymph remains for one week. The
scale-like nymph sucks plant juices. The nymph continues to develop on
the lower leaf surface into a non-feeding stage, sometimes called the
pupa. During this period the insect changes from the scale-like nymph
into an adult whitefly that usually emerges between mid morning and early
afternoon.

Cultural Management

Various practices can prevent, delay or reduce the population. Following
is a list of practices to protect ornamental crops in Florida:

Purchase cuttings and liners known to be free of whiteflies.
Whitefly free stock will ensure that the crop is started free of the
insects from the onset. Reliable producers of propagative material
exist and should be used.

Plant crops in production facilities free of whiteflies. Adult
whiteflies can fly within the production facility from an older
infested crop to a younger crop free of the pest. To prevent such
contamination, new crops should be placed into production areas only
after a previous infested crop has been removed entirely and the
greenhouse fumigated. Removing the older hosts will remove all
immature whiteflies and many of the adults.

Remove weeds and other nonessential plants from the production area.
It is difficult to maintain adequate whitefly control on weeds and
other noncrop plants in and around the production facility. Since
whiteflies can move from these to crop plants, nonessential plants
should be eliminated.








Prohibit yellow clothing and equipment from being moved within the
production area. Whiteflies are attracted to yellow' clothing and
equipment. Do not use yellow in the production area except yellow
sticky cards.

Scouting and Chemical Control

Scouting a crop regularly and using yellow sticky cards provide
information about the first arrival of whiteflies and the success of
management practices. Sticky cards should be placed among susceptible
plants from the time they arrive. Scouts should check cards once or twice
weekly for adults caught in the sticky material. Adults on traps placed
among newly arrived plants indicate the plants may have entered with
whiteflies. Inspect plants for insect stages present and apply the
insecticides appropriate to kill them (Table 1). Repeat applications in
one week.

Where yellow sticky traps continue to catch adults over an extended period
due to reintroduction or poor control, an insecticide to kill adults and
another insecticide (or the same one) to kill nymphs should be applied
weekly until control is realized. Since most pesticides do not kill
pupae, young adults may be observed daily for about one week after
spraying.

Insecticide sprays must be applied to the undersides of leaves where all
stages of the sweetpotato whitefly live and they must contact the
insects. Whiteflies do not consume treated, leaf surface tissue and
immature whiteflies do not crawl long distances so they do not come in
contact with toxic particles. Therefore insecticides must be applied to
deposit toxic particles directly onto the insects. Good leaf coverage and
good insect control are difficult when plants are spaced closely and basal
leaves are close to the production surface. Whiteflies do suck plant
juices but few effective systemic insecticides are available for whitefly
control.

Insecticides should be chosen for their effectiveness in controlling the
whitefly stages present (Table 1) and for management of insect resistance
to insecticides. The latter is achieved when choices of insecticides are
rotated among chemical classes each generation (Sanderson, 1988), which
would be about once a month for the sweetpotato whitefly.

During 1987 and 1988, about 60 insecticides were tested at the University
of Florida, IFAS, Gulf Coast Research and Education Center in Bradenton,
for their usefulness in sweetpotato whitefly management. Table 1 presents
insecticides broadly registered for use on "flower crops" in Florida and
found by the authors to be effective for the indicated stage. These
selections offer at least one product from each of five chemical classes
that can be used in field production and one from each that can be used in
greenhouse production. Other insecticides, not evaluated, also may be
useful.

In order for pesticides to be used legally, the pesticide label must
permit its use on the crop intended. Only pesticides with labels
permitting use in greenhouses are legal for that environment. Whenever a










pesticide new to one's production system first is used, the pesticide
should be tested on a small portion of the target crop and observed for
adverse crop effects.

The sweetpotato whitefly is expected to continue to be a problem for
Florida growers for years to come. However, informed producers will be
able to manage the whitefly and continue to produce high quality crops.

ACKNOWLEDGEMENT

The authors wish to acknowledge the support of American Floral Endowment,
Florida Ornamental Growers Association, Gloeckner Foundation and Ecke
Poinsettias toward research reported herein.

REFERENCES CITED

Cock, M. J. W. 1986. Bemisia tabaci--A Literature Survey on the Cotton
Whitefly with an Annotated Bibliography. C.A.B. Internat. Inst.
Biol. Control. London. 121 pp.

Greathead, A. H. 1986. Host plants. Pages 17-26 in M. J. W. Cock, ed.
Bemisia tabaci--A Literature Survey on the Cotton Whitefly with an
Annotated Bibliography. C.A.B. Internat. Inst. Biol. Control.
London. 121 pp.

Hamon, Avas B. and Victor Salguero. 1987. Bemisia tabaci, sweetpotato
whitefly, in Florida .(Homoptera: Aleyrodidae: Aleyrodinae). Fla.
Dept. Agric. & Consumer Services Entomol. Circ. 292. 2 pp.

Price, James F., David J. Schuster and Don E. Short. 1987. Recent
advances in managing the sweetpotato whitefly on poinsettia. Fla.
Ornam. Growers Assoc. Newsletter 10(5):1-4.

Sanderson, John P. 1988. Whiteflies: Chemical control and insecticide
resistance. Pages 162-71 in A. D. Ali, ed. Proc. Fourth Conf. on
Insect and Disease Management on Ornamentals. Soc. Amer. Florists.
Alexandria, Va. 214 pp.










Table 1. Insecticides broadly registered for use on "flower crops" and
found by the authors to be effective for control of sweetpotato
whitefly.


Permitted
Chemical Class and Product Site of Use


Found Effective against
Egg Nymph Pupa Adult


Organophosphate:
Plantfume 103
Dursban 50W


Synthetic Pyrethroid:
Talstar
Pounce

Macrocyclic Lactone:
Avid1


Potassium Salt of Fatty Acid:
Safer Insecticidal
Soap2


Chlorinated Hydrocarbon:
Thiodan


Greenhouse
Greenhouse
Field


Greenhouse
Field


Greenhouse
Field


Greenhouse
Field
Interiorscape


Greenhouse
Field


1. Avid label makes no claim for


control of whiteflies.


2. Safer Insecticidal Soap may be toxic to adult whiteflies directly
contacted by wet sprays.


X X




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