• TABLE OF CONTENTS
HIDE
 Historic note
 Main














Group Title: Bradenton GCREC research report - University of Florida Gulf Coast Research and Education Center ; BRA19789-12
Title: Integrated management of the sweetpotato whitefly on commercial tomato
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00065235/00001
 Material Information
Title: Integrated management of the sweetpotato whitefly on commercial tomato
Series Title: Bradenton GCREC research report
Physical Description: 22 p. : ; 28 cm
Language: English
Creator: Schuster, David J
Gulf Coast Research and Education Center (Bradenton, Fla.)
Publisher: Agricultural Research and Education Center, IFAS, University of Florida
Place of Publication: Bradenton FL
Publication Date: 1989
 Subjects
Subject: Sweetpotato whitefly -- Control -- Florida   ( lcsh )
Tomatoes -- Diseases and pests -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 12).
Statement of Responsibility: David J. Schuster ... et al.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065235
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 63760652

Table of Contents
    Historic note
        Historic note
    Main
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
Full Text





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




Ipo







GULF COAST RESEARCH AND EDUCATION CENTER---. ..
IFAS, UNIVERSITY OF FLORIDA Central Science
5007 60th Street East Library
Bradenton, FL 34203

Bradenton GCREC Research Report BRA1989-12

University of Frlridn
INTEGRATED MANAGEMENT OF THE SWEETPOTATO WHITEFLY----- .
ON COMMERCIAL TOMATO

David J. Schuster, J. F. Price & J. B. Kring1
and
P. H. Everett2


INTRODUCTION

The sweetpotato whitefly has been noted in Florida since the
late 1800's but has only been considered a pest in the state
since late 1986 (Hamon and Salguero 1987). At that time it
was heavily infesting ornamental greenhouse and saranhouse
crops, particularly poinsettia. The insect was found heavily
infesting eggplant and cucurbits on the middle east coast in
the spring of 1987. By the fall of that year, the insect was
detected in all tomato growing regions of the state but was
present in relatively low numbers. The first outbreak of the
sweetpotato whitefly in Florida tomatoes began in the late
fall of 1987 in southwest Florida and continued in the spring
of 1988. In that season, losses were estimated to be at least
$15 million. Annual losses to tomato producers in Florida,
including increased control costs as well as direct fruit
losses, are conservatively estimated to be at least $25
million.

Reports on the biology and management of this pest on tomato
have been presented at the last two meetings of the Tomato
Institute (Schuster and Price 1987, Price et al. 1988). The
information presented in those reports will be summarized and
updated with new data in this report. It is stressed that any
management program for the sweetpotato whitefly must integrate
all available methods of control and must not rely solely upon
one control tactic.


Professor of Entomology, Associate Professor of Entomology
and Adjunct Professor, respectively.
Pacific Land Company, Immokalee, FL.








2

BIOLOGY

Sweetpotato whitefly adults are small insects about 1/32 inch
long with pale yellow bodies and white wings. They resemble
small flies but are more closely related to aphids since both
adults and immatures possess piercing-sucking mouthparts.
Adults prefer the undersides of upper leaves where they
deposit minute, cigar-shaped eggs. Newly hatching nymphs
called 'crawlers' have well-developed legs and are the only
mobile immature lifestage. After finding a suitable feeding
site on the lower surfaces of leaflets, the crawlers insert
their mouthparts, begin feeding and usually do not move again.
The subsequent nymphal stages are flattened, oval scales and
the final resting, or pupal, stage is more convex and
elliptical with large, conspicuous red eyes. Developmental
time from egg to adult on tomato is about three weeks at 80F
(Coudriet et al. 1985).

The host range of the sweetpotato whitefly includes over 500
species of plants including numerous weeds and cultivated
vegetable, agronomic and ornamental crops (Greathead 1986).
Vegetables most often attacked include those in the families
Solanaceae (including tomato, eggplant and pepper),
Cucurbitaceae (including cucumber, melons and squash) and
Malvaceae (including okra). Although the list of weed hosts
is extensive and includes numerous species found in Florida,
preliminary investigations reveal that a relatively small
number of species are infested with large numbers. These
species include spurge, ceasarweed, nightshade, morning glory,
hairy indigo and primrose willow.

DAMAGE

Both adult and nymphal sweetpotato whiteflies feed on the
lower surfaces of leaflets by sucking sap with their piercing-
sucking mouthparts. Chlorotic spots may appear around feeding
sites on the upper surfaces of leaflets, particularly on
succulent plants. Whitefly adults and nymphs produce honeydew
upon which sooty mold can grow. Heavily infested plants may
become unthrifty 'and may lose leaves. Direct feeding of
adults on fruit may result in small, raised spots about 1/16
to 1/8 inch in diameter. The spots are white on immature
fruit and remain yellow as fruit ripen. Worldwide, the
sweetpotato whitefly is best known as a pest of tomato for its
ability to transmit certain virus diseases.

In Florida, the most important damage on tomato associated
with the sweetpotato whitefly has been external, irregular











ripening of fruit and increased severity of internal white
tissue. Recent field cage studies in the fall of 1988 and
the spring of 1989 at Gulf Coast Research & Education Center
(GCREC) have confirmed these field observations. In cages in
which the sweetpotato whitefly was released and in which no
attempt to control the whitefly was made, symptoms of external
irregular ripening occurred. In cages in which no sweetpotato
whiteflies were released, no symptoms were apparent. In yet
other cages in which the whitefly was released but in which
an attempt to control the whitefly was made before external
fruit symptoms appeared, symptoms were greatly reduced.

Adults have been observed ovipositing on tomato flowers under
heavy infestations; however, greenhouse studies have not
confirmed a link between flower infestations and the
development of the irregular ripening disorder. Very few
immatures hatching from eggs on flowers survive.

The causative factors) of irregular ripening is(are) not
known at this time but may be due to a toxin or to a pathogen.-
In May of 1988, tomato plants grown whitefly-free at GCREC
were exposed to whitefly adults in tomato fields in southwest
Florida that were showing irregular ripening symptoms. Other
similarly grown plants were exposed to caged whiteflies from
the above field for two weeks. None of the plants produced
fruit showing irregular ripening symptoms.

Studies are underway at GCREC to isolate sweetpotato
whiteflies that do not cause irregular ripening of tomato.
If such a strain or strains can be isolated, transmission
studies will be conducted to elucidate the nature of the
irregular ripening disorder.

SCOUTING

Any management program of the sweetpotato whitefly should be
based upon the initial detection and subsequent monitoring of
populations. Information regarding the densities of adult and
immature stages indicates the success of current management
techniques and further indicates the need to switch or
intensify management techniques.

Since adult whiteflies are attracted to yellow surfaces, such
surfaces coated with a sticky substance have been used to trap
and monitor adults. Studies at GCREC and on a commercial
tomato farm have been conducted to evaluate effects of trap
type and height and the effects of the diurnal response of
adults on the numbers of adults captured. Flat traps placed











horizontally on the bed surface were equivalent to or better
than cylindrical traps placed vertically. Both flat and
cylindrical traps indicated similar population fluctuations.

Cylindrical traps placed at or near the soil surface captured
more adults than traps placed 22 or 44 inches above the soil
surface. However, later in the tomato season, traps placed
at 44 inches in tomato field middles captured more adults than
traps placed at 22 inches or at the soil surface. This
contrasted with the field edge where traps placed at or.near
the soil surface captured more late in the season.

Cylindrical traps monitored hourly at monthly intervals in
infested tomatoes indicated that captures peaked at about 0900
to 1000 hr regardless of the time of the year. Trap captures
in September or May were higher earlier in the day and tended
to remain higher later in the day than captures in November
or January. This diurnal variation in trap captures
complicates monitoring adults with sticky traps since, for any
specific field, traps would need to be placed in the field
after 0900 hr for retrieval that day or placed in the field
for some interval of 24 hr.

Returning to a sample site more than once on any given sample
date is obviously not time-efficient for scouting. Leaving
traps in the field for some multiple of 24 hrs is a viable
alternative; however, traps left for long periods of time may
accumulate a large amount of wind-driven soil or debris or
large numbers of other insects also attracted to yellow.

We currently recommend using either flat or cylindrical traps
placed in fields for 2-3 days, depending upon the scouting
interval. Traps on field edges should be placed at or near
the soil surface season-long. Traps placed in the interior
of the field should be placed at the soil surface when the
plants are small but should be raised as the plants grow.

The distributions of immature whiteflies on the undersides of
terminal leaflets on main stems and lateral stems have also
been evaluated at GCREC. The majority of immatures are
located on leaves six to nine counting from the top; however,
there is sufficient variation between the numbers of immatures
on leaflets on main stems and on leaflets of laterals and
between plants that further studies will be conducted.

Currently, we are recommending that estimates of densities of
immatures be made on the terminal leaflet of the 7th or 8th
leaf from the top of any stem. This corresponds to the same











leaf node recommended for evaluating leafminer larval
densities. Thus, we are recommending also that the three
terminal leaflets on one stem of each of the six contiguous
plants selected per two acres for estimating leafminer
densities be utilized for estimating whitefly immature
densities.

CULTURAL CONTROL

Management of the sweetpotato whitefly must be initiated
before an infestation occurs. Cultural manipulations of
tomato crops are not generally capable of exerting complete
control of the whitefly by themselves; however, when
integrated into a total management program, they can delay,
inhibit, avoid or reduce whitefly populations so that they
are more manageable.

Transplant Production

Sweetpotato whiteflies may infest a tomato crop by way of the
transplants or by other host plants growing in the vicinity
of the tomato crop. Thus, management must begin in the
transplant production facility and not in the field.
Production structures should be located away from infested
areas if possible and should be screened to exclude invading
whitefly adults. Our recent investigations have shown that
screening must be finer than 32 x 32 mesh but can be larger
than 64 x 64 mesh. The benefit of using screen this fine must
be balanced against the potential for heat build-up in the
facility due to reduced air flow. Where possible, alternative
cooling methods should be considered to alleviate this
concern.

Adults may enter production structures through open entry
ways. All access to structures should be kept closed or
screened and those that are used frequently should have a
double entry vestibule installed. Yellow sticky traps should
be placed within the vestibule to capture adults that have
penetrated the outside entry of the vestibule.

Workers moving into or among individual structures should
avoid wearing yellow clothing or transporting equipment of
this color since adults will be attracted to these surfaces
and could catch a ride into structures. Transplants should
be inspected prior to planting to ensure that they are free
of whitefly adults or immatures.











Land Preparation and Field Maintenance

Whitefly adults may also invade fields after they are planted
by migrating from infested weeds or crops. Fields should not
be established in or near infested weeds or crops. Land
preparation should be initiated at least a month before
transplanting and should include the destruction of weeds and
volunteers on non-crop areas including the immediate field
perimeter, ditches, roadways, fallow fields, etc. Frequent
disking of fields prior to fumigating will ensure ,that
volunteer plants and weeds do not become established long
enough to support whitefly populations. Weed management must
continue throughout the crop and should include non-crop areas
as well as the fields themselves.

Plastic Mulch

UV reflective plastic mulches (aluminum film laminated or
painted onto plastic film) have been evaluated at GCREC since
the fall of 1987 in anticipation of the sweetpotato whitefly
problem. These films are well-known for their ability to
repel alighting aphids and to delay the appearance of viruses
the aphids transmit. Our studies indicate that the effects
of aluminum mulch on whiteflies is not as great as the effects
on aphids (Schuster and Kring 1988). Nevertheless, the
mulches do result in fewer whitefly adults alighting on plants
and do delay the build-up of populations of immatures. They
are not sufficient in themselves to control the sweetpotato
whitefly but as an adjunct to other control measures can
contribute meaningfully to the overall management of the pest.

Post-harvest Activities

Sweetpotato whitefly populations continue to develop on crop
plants after commercial harvest is completed and can later
infest other crops or weeds. Weeds thus infested can serve
as reservoirs for tomatoes planted in the following season.
Whiteflies must be managed in fields opened for u-pick.

Once harvest activities are completed, it is imperative that
crops be destroyed immediately. Turning off irrigation water
is too slow in killing plants and permits the continued
development of whitefly populations. The application of a
contact herbicide rapidly kills vines and reduces the numbers
of sweetpotato whitefly adults emerging from treated foliage;
however, it does not eliminate emerging adults. An
insecticide or insecticidal combination that is toxic to both
adults and immatures (see Table 1) should be applied either











prior to or in conjunction with the application of a labelled
herbicide (see the discussion on weed management elsewhere in
these proceedings).

Observations this past spring suggested that whitefly adults
may migrate distances greater than those encountered in the
confines of a single farm. In one instance, the numbers of
adults captured on yellow sticky traps in a newly planted
tomato field were three to four times greater than what was
anticipated from previous experience. There were few or no
whitefly immatures present on the seedlings and they had been
in the ground less than two weeks. Furthermore, inspections
of weed hosts on the perimeter of the field revealed few
whitefly adults or immatures present. Therefore, it, was
concluded that the whitefly adults were not originating from
the field or the weeds and that the adults were migrating from
a nearby tomato field. The nearest such field was five miles
away and had been abandoned but not destroyed. When it was
finally treated with a herbicide, the numbers of adults
trapped in the newly planted field dropped to 1/3 or 1/4 of
their previous levels. Although this does not constitute a
clear cause and affect, it does suggest that adults may
migrate and that there should be a cooperative effort among
neighboring growers of all susceptible crops (not just tomato
crops) in managing the whitefly and its host plants.

Host Plant Resistance

No commercially available cultivars of tomato are known to be
resistant to either the sweetpotato whitefly or the associated
irregular ripening disorder. Fruit from heavily infested
cherry tomato plants appear to exhibit symptoms of the
disorder but eventually appear to ripen normally. Germplasm
derived from crosses between wild species of tomato and the
cultivated tomato has been developed at GCREC for resistance
to the leafminer and for horticultural characteristics. Some
of this germplasm also has demonstrated resistance to the
sweetpotato whitefly in the field. Unfortunately, this
germplasm is not horticulturally acceptable and will not be
available for commercial production for several years.

INSECTICIDAL CONTROL

In response to the threat of the sweetpotato whitefly to
ornamental crops and in anticipation of the development of
the problem on tomatoes and other vegetables, greenhouse and
laboratory screenings of insecticides were initiated in 1987
at GCREC. Poinsettia was chosen as the test plant since the











whitefly problem, as it existed at the time, was focused on
that crop. Insecticides selected for evaluation initially
included only those with some crop registrations but were not
restricted to those registered only on ornamentals.
Insecticides registered for vegetables only or vegetables and
ornamentals were also included. Thus, immediate
recommendations on currently available and legal insecticides
could be made. Subsequently, insecticidal combinations and
new insecticides have been evaluated in attempts to find
treatments for improved whitefly control on tomatoes. In the
trials, each insecticide or insecticidal combination was
evaluated for toxicity to adults, eggs (and hatching
crawlers), small and large nymphs and pupae. Poinsettia
remains the test plant so that the results of later
evaluations with new materials can be compared with the
results of earlier evaluations.

Results of these continuing evaluations are summarized in
Tables 1 & 2. Insecticides or insecticide combinations that
are currently registered for use on Florida tomatoes and that
produced > 90% mortality of at least one lifestage of the
whitefly are listed in Table 1. Of these products, only
Thiodan, Safer Insecticidal Soap and Thirethrin are registered
for greenhouse use. There apparently was a misconception that
the insecticides previously reported were the only ones
evaluated; however, approximately 50 insecticidal treatments
have been evaluated. Therefore the list of products evaluated
that aren't registered on tomatoes or that did not produce at
least 90% mortality of at least one whitefly lifestage are
presented in Table 2.

Beginning in the spring of 1987, insecticides which appeared
promising in the greenhouse and laboratory evaluations, new
insecticides and insecticides which were being promoted to
growers by commercial firms but had not yet been evaluated,
were evaluated on field-grown tomatoes by GCREC researchers
and cooperators. The results of these trials are presented
in Tables 3-10. Three of the trials were conducted on
commercial farms with two of them being conducted with
commercial application'equipment (Tables 4,5,7 and 8). Three
other trials using hand-held application equipment on smaller
plots at IFAS research centers were also conducted.

In every trial, at least one insecticide or insecticide
combination resulted in fewer whitefly immatures on foliage
compared to untreated checks. Although there were reductions
in the extent of irregular ripening, no treatment eliminated
the disorder. Symptoms of fruit from treated plots were much











more severe in small plot trials (Tables 3,6,9 and 10) than
in large plot trials (Tables 5 and 8). This was particularly
true in the small plot trial in a commercial field (Table 3)
where whitefly adults quickly re-infested plots after
spraying. Therefore, the severity of the disorder resulting
from specific treatments in small plots would be expected to
be lower when the treatments are applied to larger areas.

New insecticides or insecticides that had not been evaluated
in the greenhouse and laboratory trials that appeared
effective in controlling the whitefly in the field trials
include Brigade (a pyrethroid) (Table 10) and Endocide Plus
(a combination of Thiodan and Parathion) (Table 6). Agri-Mek
appeared ineffective in a small plot trial in a commercial
field (Table 3) but has since appeared effective in both small
plots (Table 6) and in large plots under commercial conditions
(Tables 7 & 8). In this latter situation, Agri-Mek was
alternated weekly with Thiodan. Guthion was effective against
small nymphs in the laboratory studies (Table 1) but was
ineffective in whitefly management in a field trial (Table 3).
Alternations of insecticides of. different classes (see
comments below) were evaluated- in commercial fields using
commercial application equipment and were found to result in
reduced populations of whitefly immatures and in reduced
irregular ripening (Tables 4,5,7 and 8).

There are a number of factors growers should take into
consideration when developing an insecticide program for their
farms. Before selecting and applying any insecticide, growers
should read the label thoroughly. The insecticide label is
the law and insecticides cannot be used contrary to the label.
Some of the insecticides listed in Tables 2-10 are not
registered on tomatoes and cannot be used. These insecticides
are included only to illustrate the scope of research
completed and the range of susceptibility of the sweetpotato
whitefly to a broad base of insecticides.

Thorough coverage of lower surfaces of leaves with
insecticides is essential, since all lifestages of the
whitefly occur on the 'undersides of foliage and since eggs,
sessile nymphs and pupae do not move and must be impinged by
contact insecticides. Since whiteflies are sucking pests,
only systemic insecticides are ingested. Vydate is the only
systemic insecticide listed in Table 1.

Resistance of the sweetpotato whitefly to organophosphate and
synthetic pyrethroid insecticides has been reported in
California (Prabhaker et al. 1985). In order to avoid or












inhibit the development of resistance in the insect in
Florida, it is recommended that insecticides of different
classes be selected and that they be alternated. Various
alternations including pyrethroids (Ambush, Asana XL), a
chlorinated hydrocarbon (Thiodan), potassium salts of fatty
acids (Safer Insecticidal Soap) and a carbamate (Vydate) were
effective in managing both the sweetpotato whitefly and
irregular ripening under commercial conditions in south
Florida (Tables 4,5,7 and 8).

Since all lifestages of the sweetpotato whitefly will probably
be present in tomato fields, growers should select
insecticides or insecticide combinations or alternations that
kill adults and immatures. Applications should be made weekly
when the insect first appears and increased to twice weekly
if populations increase. No action thresholds for timing
insecticidal applications are available at the present time.

Some of the insecticidal products listed in Table 1 and
evaluated in the field trials have restrictions on their
labels limiting the amount of active ingredient that can be
applied to a crop. These include Ambush, Asana, Pounce,
Pydrin, Vydate; Thiodan and the combination of Monitor and
Pounce. When applying insecticides frequently, one may need
to alternate among three or more different insecticides to
avoid exceeding label restrictions. Growers are again
encouraged to consult product labels before applying any
pesticide.

BIOLOGICAL CONTROL

Biological control of the sweetpotato whitefly has been
studied for many years at various sites around the world.
Several species of small parasitic wasps have been recovered
on various host plants in Florida. A biological control
project has recently been initiated at GCREC to identify and
evaluate such parasites occurring in Florida and elsewhere in
the Caribbean. Promising parasite species will be evaluated
for their ability to attack the whitefly on a variety of host
plants. Susceptiblity of promising parasites to selected
insecticides commonly utilized on tomatoes will be determined
so that the parasites can be integrated into existing pest
management programs. If promising parasites from the
Caribbean are found, they will be considered for release in
Florida to aid in management of the sweetpotato whitefly.

A pathogenic fungus has been recovered in the greenhouse and
may be effective in managing the sweetpotato whitefly in












transplant production facilities (Osborne, personal
communication). The fungus has not been recovered in the
field. It is still under investigation and is not
commercially available.

Although the sweetpotato whitefly has only been a pest of
Florida tomatoes for about a year and a half, it is likely to
continue as a problem for years to come. Integrating cultural
and insecticidal control tactics offers the best approach to
successfully managing the pest. Reliance soley .upon
insecticides could lead to the development of resistance in
the whitefly and compound an already bad situation.
Biological control and host plant resistance offer
encouragement for the successful long-term management of the
pest in the future.

PRECAUTIONS
Commercial products are mentioned in this publication solely
for the purpose of providing specific information. Mention
of a product does not constitute a guarantee or warranty of
the products by the Agricultural Experiment Station or an
endorsement over products not mentioned.

This publication also reports research involving pesticides.
It does not contain recommendations for their use, nor does
it imply that the uses discussed here have been registered.
All uses of pesticides must be registered by appropriate state
and federal agencies before they can be recommended.

ACKNOWLEDGEMENTS
The authors wish to acknowledge the many excellent research
efforts that are underway within the University of Florida,
IFAS and within the USDA-ARS but which are not specifically
mentioned in this report: Drs. K. R. Narayanan, H. H. Bryan
and R. T. McMillan of the IFAS Tropical Research & Education
Center, Homestead; Dr. L. S. Osborne of the IFAS Central
Florida Research & Education Center, Apopka; Drs. R. K.
Yokomi, J. P. Shapiro and K. A. Hoelmer of the USDA-ARS
Horticultural Research Lab, Orlando; and Dr. G. A. Leibee of
the IFAS Central Florida Research & Education Center, Sanford.

We wish also to acknowledge and express our appreciation to
our technical staff and to the IFAS Southwest Florida Research
& Education Center, ABC Farms, Pacific Land Co., Collier
Enterprises and IPM Consultants to the tomato industry for
their invaluable assistance and cooperation.













REFERENCES CITED

Coudriet, D. L., N. Prabhaker, A. N. Kishaba and D. E.
Meyerdirk. 1985. Variation in developmental rate on
different hosts and overwintering of the sweetpotato
whitefly, Bemisia tabaci (Homoptera: Aleyrodidae).
Environ. Entomol. 14:516-519.

Greathead, A. H. 1986. Host plants. Pages 17-25 In M. J.
W. Cook, ed. Bemisia tabaci--a literature survey on the
cotton whitefly with an annotated bibliography. C.A.B.
Int. Inst. Biol. Control. London. 121 pp.

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

Prabhaker, N., D. L. Coudriet and D. E. Meyerdirk. 1985.
Insecticide resistance in the sweetpotato whitefly, Bemisia
tabaci (Homoptera: Aleyrodidae). J. Econ. Entomol. 78:
748-752.

Price, J. F., D. J. Schuster and J. B. Kring. 1988.
Management of the sweetpotato whitefly on tomato crops in
South Florida. Univ. Fla., IFAS, Bradenton GCREC Res.
Rept. BRA1988-15. 6 pp.

Schuster, D. J. and J. F. Price. 1987. The western flower
thrips and the sweetpotato whitefly: new pests threatening
Florida tomato production. Univ. Fla., IFAS, Bradenton
GCREC Res. Rept. BRA1987-16. 7 pp.

Schuster, D. J. and J. B. Kring. 1988. Management of insects
on tomato with UV-reflective mulches. Pages 5-19 In Report
of tomato research supported by the Florida Tomato
Committee 1987-1988. Univ. Fla., IFAS, Gainesville. 69 pp.












13

Table 1. Pesticides registered for use on tomatoes that produced > 90% mortality of at least one
lifestage of the sweetpotato whitefly in greenhouse and laboratory evaluations. GCREC,
1987-89.


Effective against indicated life stagesz
Chemical class Unhatched Crawlers from Small Large
of compound Product eggs treated eggs nymphs nymphs Pupae Adults

Pyrethroid Ambush + ++++ ++ +++ + +++
Asana + ++++ ++ 4+ +
Pounce + +++ ++++ + + ++
Pydrin + +++ -

Organophosphate Guthion 2L + + + + +

Carbamate Lannate + ++ ++ ++ ++ ++++
Vydate L + ++++ ++ ++ +

Chlorinated
hydrocarbon Lindane + + + + + ++++
Thiodan + + ++ + ++++

Miscellaneous Safer Soap + + ++++ +++ ++++ +
Stylet Oil + +++ ++++ + + +

Combinations Monitor + Pounce + +++ +++ ++++ + ++++
Thiodan + Pyrenone + + ++ ++ + ++++


= 50-69%; and + =


ZPercent mortality was rated by the following: ++++ = 90-100X; +++ = 70-89%; ++
Less than 50%. A dash indicates that the lifestage was not evaluated.










14



Table 2. Pesticides evaluated in the Laboratory and greenhouse for control of specific lifestages of the
sweetpotato whitefly. These pesticides either are not registered for.use on tomato or did
not produce at Least 90% mortality against at Least one lifestage. GCREC, 1987-89.



Effective against indicated Life stages
Chemical class Registration Unhatched Crawlers Small Large
of compound Product statusz eggs from eggs nymphs nymphs Pupae Adults


Pyrethroid


Organophosphate














Carbamate


Chlorinated
hydrocarbon

Microbial
derivative

Miscellaneous


Danitol
Mavrik
Pyrenone
Talstar


Cygon
Diazinon
Dibrom
Disyston G
Dursban 50W
Dursban 20 MEC
Malathion
Monitor
Orthene
Plant Flume 103
Zotone

Dycarb
Vydate G
Sevin
Temik


Kelthane


Avid (Agri-Mek)


Amitraz
Apex
Margosan-0
Morestan
Natur'l Oil
Sulfur
UBI k840


Combination Ambush +
Butacidex
Asana +
Butacidex
Danitol +
Monitor
Danitol +
Orthene
Mavrik +
Apex
Talstar +
Orthene
Safer Soap +
Thiodan


.4
.4.

+*


+


+

+*+


+


.+

.4.




"+


+



+"


.4

.4


+~

+


'+4 .4+
.4 .4
+.+




+ +


+

+
+
+
* +

+
+
+


+

+
+


+ +


+4 +++ + ++


.4.4 +4+

~++
+ +
++

+++




+4 +~




.4+ +4.4

.4.4 +4.


+ +++









+ +++
+ +++


LA = some agricultural registrations other than registrations for vegetables; E = experimental or no
agricultural registrations; V = some vegetable registrations other than tomatoes; T = registered for use
on tomatoes; t = registered for use on Florida tomatoes only.
YPercent mortality relative to an untreated check were rated by the following: ++++ = 90=100%; +++ = 70-89;
++ = 50-69X; and + = Less than 50%. A dash indicates that the lifestage was not evaluated.
XButacide = activist or synergist.


"+


+"
'+4'
"+









Table 3. Influence of twice weekly applications of selected insecticides or insecticide combinations on the sweetpotato whitefly and irregular
ripening (IRR) on commercially-grown tomatoes. Immokatee, Spring 1988.z


No. sweetpotato whitefly immatures /ten-20 mm leaf disks
Amount/ Unhatched eggs Nymphs Pupae Emerged pupae Adult X
Treatment 100 gat 12 May 19 May 26 May 31 May 12 May 19 May 26 May 31 May 26 May 31 May 26 May 31 May ratingy IRR

Agri-Mek 0.15 EC 8 oz 51.1bcx 83.4c 128.6d 294.3c 21.6ab 55.3cd 116.5c 147.5c 12.1b 16.8b 12.3b 28.3c 4.3bc 76.0
Asana XL 0.66 EC 7 oz 40.7b 82.1c 56.3c 64.0b 19.Oa 34.5bc 34.1b 30.Ob 4.6a 2.8a 7.6ab 9.3ab 1.5a
Asana XL 0.66 EC 7 oz
+ Butacide 8 EC 6 oz 20.3a 13.6a 12.5a 15.Oa 15.6a 14.3a 8.8a 5.3a 1.6a 2.5a 6.8ab 9.0ab 1.1a 67.1a
Guthion 2L 2 pt 61.3bc 152.6d 228.4ed 352.3c 25.6ab 50.3cd 143.Oc 243.8cd 13.7b 18.0b 9.9ab 20.3bc 3.6b 77.2a
Thiodan 50 UP 1 Lb
+ Safers Soap 2 gal 15.5a 26.1b 27.5b 57.3a 14.5a 22.5ab 26.0b 29.8b 2.8a 7.0a 6.3a 5.8a 1.4a 81.2a
Check 67.8c 141.1d 277.8e 378.8c 31.4b 63.7d 183.1c 322.8d 17.3b 39.0c 10.9ab 30.3c 4.5c 72.8a


ZPlots were three, 15 ft. long rows replicated four times. Treatments were applied with a hand-held CO2 sprayer twice weekly for five weeks
beginning Apr. 28. The sprayer delivered 125 gpa.
YThe number of adults present at harvest were rated 1-5 for increasing abundance.
xMeans within columns followed by the same letter are not significantly different at the P = 0.05 level, Duncan's multiple range test.
.ln












Table 4. Evaluation of selected insecticides alternated at least weekly for management of the sweetpotato
whitefly on commercially-grown tomatoes. Imnokalee, Fall 1988.z


No. sweetpotato whitefly immatures/10 leaflets
Treatment Amount/ Crawlers Sessile nymphs
alternationy 100 gal 16 Nov 23 Nov 30 Nov 7 Dec 14 Dec 16 Nov 23 Nov 30 Nov 7 Dec 14 Dec

Ambush 2EC 8 oz
& Thiodan 3EC 2.5 pts 6.3ax 25.3a 16.7a 2.7a 44.3a 5.0a 2.3a 15.3a 9.3a 4.3a

Ambush 2EC 8 oz
& Thiodan 3EC 1.5 pts
+ Safers Soap 1 gal
+ Blendex' 1 pt 4.3a 20.7a 26.3a 15.0a 52.3a 2.0a 6.7a 25.7a 24.3ab 2.0a

Asana 0.66EC 6 oz
& Vydate 2LW 2 pts 11.3ab 29.3a 27.3a 27.0ab 50.3a 11.0a 10.3ab 16.3a 34.3ab 4.0a

Control 17.3b 33.7a 53.0b 64.0b 91.3b 12.0a 24.3b 44.0a 97.7b 12.7b


ZTransplants were set Sept. 9 in six, 560 ft long plots replicated three times. Treatments were applied
with a commercial, 6-row sprayer on Sept. 27; Oct. 4,11,18 and 25; Nov. 1,8,15,22 and 30; Dec. 2,6,9,13,
16,20,23, and 27. The sprayer delivered 40-100 gpa.
An "&" indicates an alternation of treatments and a "+" indicates a tank mix combination.
xMeans within columns followed by the same letter are not significantly different at the P = 0.05 level,
Duncan's multiple range test.
wThe rate of Vydate 2L was increased to 3 pts for the last six sprays.









Table 5. Evaluation of selected
whitefly and irregular
from Table 4).z


insecticides alternated at least weekly for management of the sweetpotato
ripening (IRR) on commercially-grown tomatoes. Immokalee, Fall 1988 (continued


Un~ awnetmtatn uhitpfiv nunneiiO Leafle


Average IRR ratinqx
As First Second Third Season


alternationy 100 gat 16 Nov 23 Nov 30 Nov 7 Dec 14 Dec harvest harvest harvest average

Ambush 2EC 8 oz
& Thiodan 3EC 2.5 pts 0.3a" 1.3a 0.3a 4.0a 9.3ab 1.1a 1.6a 2.0a 1.6a

Ambush 2EC 8 oz
& Thiodan 3EC 1.5 pts
+ Safers Soap 1 gal
+ Blendex 1 pt 0.7a 1.0a 2.0a 3.7a 1.3a 1.1a 1.1a 2.0a 1.6a

Asana 0.66EC 6 oz
& Vydate 2Lv 2 pts 1.3a 2.0a 0.7a 4.0a 7.7ab 1.0a 1.0a 2.3b 1.6a

Control 8.3a 4.3a 3.0a 7.7a 20.Ob 1.4b. 2.2b 2.6c 2.1a

'Transplants were set Sept. 9 in six, 560 ft long plots replicated three times. Treatments were applied with
a commercial, 6-row sprayer on Sept. 27; Oct. 4,11,18 and 25; Nov. 1,8,15,22 and 30; Dec. 2,6,9,13,16,20,23, and
27. The sprayer delivered 40-100 gpa.
YAn "" indicates an alternation of treatments and a "+" indicates a tank mix combination.
XFruit were rated 1 to 4 for increasing severity of symptoms.
wMeans within columns followed by the same letter are not significantly different at the P = 0.05 level, Duncan's
multiple range test.
VThe rate of Vydate 2L was increased to 3 pts for the last six sprays.


Treatment


Amornt/












Table 6. Impact of insecticidal products on management of the sweetpotato whitefly and irregular ripening (IRR) on tomato.
SWFREC, Immokalee, Fall 1988.z


No. sweetpotato whitefly immatures/l0 leaflets
Amount/ Crawlers Sessile nymphs Pupae IRRy
Insecticide 100 gal 23 Nov 16 Dec 27 Dec 23 Nov 16 Dec 27 Dec 23 Nov 16 Dec .27 Dec rating

Agri-Mek 0.15EC 8 oz 7.5abx 4.2a 3.8a 4.0a 15.8a 7.8a 0.5a 3.0a 1.5ab 3.0a

Endocide Plus EC
(Endosulfan 2EC +
Parathion 1EC) 1 qt 5.2ab 6.5ab 2.8a 1.8a 9.0a 3.5a 0.2a 0.2a 1.2ab 3.3a

Rotacide 5EC + 5 pts
Butacide 8 oz 12.5ab 16.2c 11.0a 2.5a 28.2a 13.2ab 1.Oa 3.5a 2.0ab 3.4a

Thiodan 3EC 2.5 pts 1.5a 3.5a 4.8a 0.8a 7.5a 4.8a 1.0a 0.8a 0.8a 3.1a

Control 15.0b 11.0b 9.2a 9.5b 54.8b 24.8b 2.0a 3.0a 2.5b 3.4a


ZTransplants were set Sept. 15 in three, 20 ft. Long plots replicated three times. Treatments were applied with a 3-row,
tractor-mounted plot sprayer on Sept. 30; Oct. 9,18, and 25; Nov. 10,16 and 25; Dec. 3,7,9,15,20 and 23. The sprayer
delivered 50-100 gpa.
YFruit were rated 1 to 4 for increasing severity of symptoms.
XMeans within a column followed by the same letter are not significantly different at the P=0.5 level, Duncan's multiple
range test.











Table 7. Management of the sweetotato whitefly on commercially-grown tomatoes with twice weekly alternations of insecticides.
Imnokalee, Spring 1989.


Treatment

alternationy

Agri-Mek 0.15 EC
& Thiodan 3EC

Agri-Mek 0.15 EC
& Thiodan 3 EC

Ambush 2 EC
& Thiodan 3 EC

Asana XL 0.66 EC
& Thiodan 3 EC

Asana XL 0.66 EC
& Vydate 2 L

Check


Amount/

100 gal

8 oz
2.5 pts

4 oz
2.5 pts

8 oz
2.5 pts

6 oz
2.5 pts

6 oz
3 pts


21 Feb


10.7ax


6.7a


15.7a


5.3a


4.0a

61.0b


7 Mar


12.3a


7.0a


25.0ab


7.0a


18.3ab

39.0b


No. sweetpotato whitefly imnatures/l0 leaflets
Crawlers Sessile nymphs

21 Mar 4 Apr 18 Apr 2 May 21 Feb 7 Mar 21 Mar 4 Apr


17.3a 14.Oa 73.3a 232.Oa 9.0a. 0.3a 35.7a 25.0a


11.7a 18.3a 90.3a 159.3a 4.0a 1.3a 33.7a 22.7a


19.3a 11.3a 133.7a 125.Oa 6.0a 5.0a 21.3a 22.3a


11.0a 14.3a 43.Oa 67.0a 1.7a O.Oa 25.7a 15.7a


24.3a 17.7a 94.7a 247.7a 1.3a 0.7a 51.3a 31.0a

46.Ob 45.7b 243.3b 1160.7b 53.7b 12.Oa 195.Ob 95.Ob


ZTransplants were set Jan. 24 in six, 560 ft. Long plots replicated three times. Treatments were applied with a commercial, 6-row sprayer
on Jan. 27 and 30; Feb. 3,7,10,14,17,21 and 28; Mar. 3,8,11,14,17,21,24,28 and 31; Apr. 4,7,11,19,25 and 28. The sprayer delivered 40-
100 gpa.
YInsecticides were alternated for each spray.
XNeans within a colunn followed by the same letter are not significantly different at P = 0.05, Duncan's multiple range test.


18 Apr


29.7a


37.3a


53.7a


9.0a


30.3a

127.7b


2 May


139.3a


137.3a


116.7a


40.3a


162.3a

954.3b











Table 8. Management of the sweetpotato whitefly and irregular ripening (IRR) on comnercially-grown tomatoes with twice weekly alternations of
insecticides. Imnokalee, Spring 1989 (continued from Table 7).z


No. whitefly pupae/ External fruit IRRX Internal fruit
Treatment Amount/ 10 leaflets Rating X unmarketable fruit white tissue rating

alternationy 100 gal 21 Mar 4 Apr 18 Apr 2 May 18 Apr 3 May Total 18 Apr 3 May Total 18 Apr 3 May Total

Agri-Hek 0.15 EC 8 oz
& Thiodan 3 EC 2.5 pts 1.7av 4.0a 3.0a 11.0a 2.0a 2.lab 2.1a 0.6a 9.6ab 7.0b 3.lab 3.8b 3.5a

Agri-Hek 0.15 EC 4 oz
& Thiodan 3 EC 2.5 pt 0.7a 9.0ab 6.7a 13.Oa 2.0a 2.2b 2.1a 0.Oa 13.1b 6.5b 2.9a 3.8b 3.3a

Ambush 2 EC 8 oz
& Thiodan 3 E 2.5 pts 1.7a 9.3ab 8.0a 7.0a 2.0a 2.lab 2.1a 0.Oa 7.5ab 5.lab 3.lab 3.8b 3.5a

Asana XL 0.66 EC 6 oz
& Thiodan 3 EC 2.5 pts 0.Oa 5.3ab 1.3a 3.3a 2.0a 2.0a 2.0a 0.Oa 4.2a 2.4a 3.0ab 3.4a 3.5a

Asana XL 0.66 EC 6 oz
& Vydate 2 L 3 pts 0.3a 5.3ab 3.7a 10.0a 2.0a 2.1ab 2.1a 0.3a 9.8ab 5.4ab 3.0ab 3.8b 3.5a

Check 12.3b 26.7b 11.0a 95.3b 2.0a 2.8c 2.4b 2.7b 54.0c 31.2c 3.3b 4.3c 3.9b

ZTransplants were set Jan. 24 in six, 560 ft. Long plots replicated three times. Treatments were applied with a commercial, 6-row sprayer on
Jan. 27 and 30; Feb. 3,7,10,14,17,21 and 28; Mar. 3,8,11,14,17,21,24,28 and 31; Apr. 4,7,11,19,25 and 28. The sprayer delivered 40-100 gpa.
IYnsecticides were alternated for each spray.
XFruit were rated 1 to 4 for increasing severity of symptoms. Fruit rated 3 or 4 were considered unmarketable. Percent data were transformed
arcsin of the square root of the proportion prior to analysis but are presented in the original scale.
WFruit were cut transversely and rated 1 to 5 for increasing severity of white tissue.
vMeans within a column followed by the same letter are not significantly different at P = 0.05, Duncan's multiple range test.











Table 9. Twice weekly alternations of insecticides for management of the sweetpotato whitefly, leafminers and irregular ripening (IRR) on tomato.
SUFREC, Immnokalee, Spring 1989.z


External Internal
No./10 leaflets fruit IRRX fruit
Sweetpotato whitefly immatures Leafmines X white
Treatment Amount/ Crawlers Sessile nymphs Pupae Large Small unmarketable tissue
alternationy 100 gal 25 Apr 8 May 25 Apr 8 May 25 Apr 8 May 25 Apr 8 May 25 Apr 8 May Rating fruit ratingw

Ambush 2 EC 8 oz
& Thiodan 3 EC 2.5 pts 16.8aV 59.5a 24.8a 59.2a 2.5a 11.8a 18.2b 12.0bc 5.5a 5.0a 2.2ab 14.4ab 3.6abc

Monitor 4 EC 1.5 pts
+ Ambush 2 EC 6.4 oz
& Thiodan 3 EC 2.5 pts 30.0ab 32.8a 43.8ab 24.2a 2.5a 5.5a 14.2b 13.0bc 9.5abc 8.5a 2.1a 7.9a 3.2a

Monitor 4 EC 2.0 pts
& Agri-Mek
0.15 EC 8 oz 63.5ab 221.5b 114.2c 125.5a 9.8ab 28.5b 3.8a 2.0a 4.5a 2.2a 2.4bc 25.1bc 4.0cd

Monitor 4 EC 2.0 pts
& Ambush 2 EC 8 oz 31.2ab 47.2a 51.8ab 68.2a 5.5a 10.8a 21.0b 13.5bc 12.5bc 6.0a 2.1a 10.6a 3.4ab

Monitor 4 EC 2.0 pts
& Thiodan 3 EC 2.5 pts 62.8ab 85.0a 103.8bc 57.8a 5.8a 10.2a 14.8b 7.5ab 7.0ab 5.0a 2.1a 11.9ab 3.7bc

Check 73.2b 360.5c 100.2bc 334.Ob 16.8b 35.Ob 22.Ob 16.0c 14.8c 8.8a 2.5c 33.6c 4.2d


ZTransplants were set Feb. 15 in three, 20 ft. Long plots replicated four times. Treatments were applied with a 3-row, tractor-mounted plot
sprayer on Mar. 13,16,20,23,27 and 31; Apr. 3,6,10,13,17,20,24 and 27; May 1,4,8,11,16 and 19. The sprayer delivered 40-80 gpa.
YAn "&" refers to alternations of insecticides and a "+" refers to tank mixes.
xFruit were rated 1 to 4 for increasing severity of symptoms. Fruit rated 3 or 4 were considered unmarketable. Percent data were transformed
arcsine of the square root of the proportion prior to analysis but are presented in the original scale.
wFruit were cut transversely and rated 1 to 5 for increasing severity of white tissue.
vMeans within a column followed by the same letter are not significantly different at the P = 0.05 level, Duncan's multiple range test.














Table 10. Evaluation of pyrethroid insecticides for control of the sweetpotato whitefly and irregular
ripening (IRR) on tomato. GCREC, Bradenton, Spring 1989.z


No. sweetpotato whitefly
Amount/ imnatures/10 Leaflets External fruit IRRY
Treatment 100 gal Crawlers Sessile nymphs Pupae Rating X unmarketable fruit

Amno 2.5 EC 3 oz 370.2bx 269.0a 36.5ab 3.1b 71.4b

Brigade 10 WP 9.6 oz 45.8a 29.5a 2.2a 2.6a 45.5a

Pounce 3.2 EC 6 oz 463.8b 210.3a 23.2ab 3.1b :75.9b

Check 668.2c 753.0b 56.5b 3.4c 87.3c

'Transplants were set Feb. 1 in three, 20 ft. long plots replicated four times. Treatments were applied
with a 3-row, high-clearance sprayer on Mar. 27; Apr. 12, 19 and 26; May 3, 10, 17 and 24. The sprayer
delivered 60-100 gpa.
YFruit were rated 1 to 4 for increasing severity of symptoms. Fruit rated 3 or 4 were considered un-
marketable. Percent data were transformed arcsine square root of the proportion prior to analysis but data
are presented in the original scale.
XMeans within a column followed by the same letter are not significantly different at the P = 0.05 level,
Duncan's multiple range test.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs