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Proceedings: Fourth Meeting of the International Council on Lethal Yellowing
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Title: Proceedings: Fourth Meeting of the International Council on Lethal Yellowing
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Publication Date: 1980
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Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page 1
        Title Page 2
    Table of Contents
        Table of Contents 1
        Table of Contents 2
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Full Text

of the







Fort Lauderdale, Florida

August 13-17, 1979

Edited by
D. L. Thomas, F. W. Howard and H. M. Donselman

Published by
Agricultural Research Center
Institute of Food and Agricultural Sciences
University of Florida
Fort Lauderdale
for the
International Council on Lethal Yellowing

Publicaton FL-80-1




AUGUST 13-17, 1979


Broward County Board of Commissioners
City of Fort Lauderdale
International Palm Society

City of Lauderdale-by-the-Sea
City of Lighthouse Point
Rio Vista Civic Association

Mrs. John G. Wood, President FFGC, Inc.
Broward Garden Club
Evening Garden Club of Fort Lauderdale
Florida Federation of Garden Clubs, Inc., Dist. XI
Federated Garden Circles of Fort Lauderdale, Inc.
Cassia Garden Circle
Chorisia II Garden Circle
Hibiscus Garden Circle
Lake Placid Garden Club of Lighthouse Point
Men's Garden Club of Fort Lauderdale

Robert P. Cacner
Century Bank Hollywood, Florida
Delta Airlines
Arthur Donadio
Fort Lauderdale Chamber of Commerce
Hollywood Federal Savings & Loan Association
Landmark First National Bank of Fort Lauderdale
Carl L. Mayhue
Native Tan of South Florida
Voyager Sightseeing Train, Inc.
New Orleans Homes, Inc.
Real Estators of America, Inc.
City of Sunrise

W. B. Ennis, Jr., Chairman
L. Chiarappa, Secretary G. Martinez-Lopez
E. A. Addison D. H. Romney
M. Dollet H. Waters

W. B. Ennis, Jr.

H. G. Basham
H. M. Donselman
F. W. Howard

R. E. McCoy
D. L. Thomas
J. H. Tsai

Lewis E. Watson, Chairman
Woneta Bellevue Floyd Hull
Dwight Burkam Carl Mayhue
Gertrude Cole Michael Moore
Ilo B. Cox Marie Rey
Eason Dobbs John Schlegel
Robert Garvin E. Clay Shaw
Virginia Young

Mrs. E. M. Rey


Preface W. B. Ennis, Jr. .......... ....... .................................

Technical Summary of the Fourth Meeting of ICLY S. J. Eden-Green ....................... 1

An Evaluation of Lethal Yellowing Research Progress and Priorities P. Hunt ................... 3

Cocos Palm as a World Crop L. Chiarappa and P. Poetiray ................................. 5
Growing Plantation Coconut Palms (Abstract) D. H. Romney .............................. 6
Florida's Palms Who Needs Them? (Abstract) -H. M. Donselman ........................... 6

Insect Vectors of Procaryotic Plant Pathogens A. H. Purcell ............................. .. 7
Lethal Yellowing and Translocation in Palms M. H. Zimmermann......................... 7
Current Status of Spiroplasmas and Mycoplasmas Isolated from Plants and Insects T. A. Chen .... 7

An Approach to the Serological Study of the Mycoplasmas of Lethal Yellowing in the Coconuts in
West Africa M. Dollet, C. Saillard, O. Garcia Jurado, J. C. Vignault, D. Gargant, J. G. Tully
andJ. M. Bove .......................... ........... .. ....... ........... 8
Xylem Transport in Palms with Lethal Yellowing H. G. Basham and F. M. Eskafi................. 8
Phloem Ultrastructure of Palms with Lethal Yellowing D. L. Thomas. ........................ 8
Rapid Propagation of Date Palms through Tissue Culture B. H. Tisserat. ................... .. 8
Isozymes as Genetic Markers in Palmae B. H. Tisserat .................................... 9
The Distribution of Spiroplasmas within Infected Plants Varies During the Course of Infection -
D. B. Archer, J. Best and K. A. Plaskitt ........... ..... ...... .............. 9
Scanning Electron Microscopy of Aster Yellows Spiroplasma K. Maramorosch ................. 9

The Acholeplasmas: Biological Characteristics and New Developments in Host Distribution -
J G Tu lly .... .... ....... ...... ....... .. ... .. ... .... .. ..... ... ... .. ... .... .. .... 1 0
Acholeplasmas and Lethal Yellowing Disease I. Present Status S. J. Eden Green, J. G. Tully
and R. Townsend. .............. .......................................... 10
Acholeplasmas and Lethal Yellowing Disease II. Transmission Experiments S. J. Eden-Green,
P. G. Markham and R. Townsend ......... ................................. .. 10
Acholeplasmas and Lethal Yellowing Disease-Ill. Microbiological and Serological Studies -
R. Townsend, S. J. Eden-Green, P. G. Markham, D. B. Archer and M. F. Clark .............. 11
Isolation and Characterization of Mycoplasmas from Floral Surfaces -
R. E. McCoy and H. G. Basham ................................... .... ............. 11
ELISA for the Detection of Lethal Yellowing Agent in Diseased Coconuts S. F. Nome,
B. C. Raju and G. Nyland. .......................................................... 1 1
Multiplication of Spiroplasmas in Larvae of the Wax Moth, Galleria mellonella (L.) -
R. E. McCoy and M. J. Davis ............................. .......................... 1 2
Effect of Spiroplasmas on Growth Rate and Survival of Wax Moth Larvae -
R. V. Dowell and R. E. McCoy ................... ........ ......... ..... .. ......... 12
Isolation of Spiroplasmas from Leaf hoppers Exposed to Aster Yellows and X Disease -
B. C. Raju, A. H. Purcell and G. Nyland........................................ .. ... 12
Long Term Storage of the Aster Yellows Agent in Frozen Insects A. J. Smith .................. 12
Factors Affecting Maintenance in vitro of Aster Yellows Pathogenicity A. J. Smith ............. 12

Homopterans Feeding on Coconut Palms in Jamaica F. M. Eskafi. ................... ....... 13
Attempts to Transmit Coconut Lethal Yellowing Disease with Palm-Feeding Fulgoroidea
in Jamaica, 1977-79 A. J. Dabekand H. Waters .................................... 13
Attempts to Transmit Coconut Lethal Yellowing Disease with Cicadelloidea in Jamaica, 1977-79 -
A. J. Dabek and H. W aters ........................................................ 13
Lethal Yellowing Transmission Experiments with Myndus crudus Van Duzee F. W. Howard..... 13
The Leaf hopper Macrosteles fascifrons as a Host but Non-vector of X Disease Agent -
A. H. Purcell, J. Richardson and A. Finlay ............................................ 14
Progress in Search for Lethal Yellowing Vector(s) J. H. Tsai ............................ 14
Symptoms Produced by Plants in Response to Injection A. S. Alivizatos and R. Townsend ...... 14
Population Studies of Myndus crudus Van Duzee in Florida F. W. Howard ................... 15

Foliar Insecticide Applications Reduce Spread of Palm Lethal Decline F. W. Howard ........... 15
The Probable Origin of Lethal Yellowing and its Co-identity with Other Wilt Diseases of Coconut -
L. Chiarappa ......................... ........... .. ........ .... ................. 15
Did Lethal Yellowing Disease Originate in Malaysia? K. Maramorosch. ...................... 15
Field Resistance of Malayan Dwarf D. H. Romney ............... ...................... 15
Assessing Field Resistance to Lethal Yellowing in Coconut Varieties B. O. Been .............. 16
Ornamental Palms Resistant to Lethal Yellowing for Florida H. M. Donselman ................ 16

A Coconut Disease of Uncertain Etiology in Indonesia P. Hunt ............................. 16
Occurrence of Fusarium oxysporum and Gliocladium vermoeseni on Phoenix canariensis
in California- T. V. Feather, H. D. Ohrand D. E. Munnecke ............................. 16
Current IRHO Research on Intraphloemic Flagellated Protozoa Associated with Marchitez
in South America M. Dollet ................................................... 17
Preliminary Observations on the Control of Hartrot of Coconut by Insecticidal Application -
V. T.A alexander .................................................. ............ 17
Varietal Resistance Studies for Hartrot of Coconut V. T. Alexander. ......................... 17
Flagellated Protozoans in Coconut Palms in the Southwest of Colombia G. Martinez-Lopez,
O. JimenezandE. Mena-Tascon ..................................................17
Occurrence of Flagellated Protozoa in "Case 9" Disease of African Oil Palm in Colombia -
R. E. McCoyandG. Martinez-Lopez ................................. .............. 17
Preliminary Studies on Lethal Palm Blight J. K. Dunaway and D. G. Mead ................... 18
Pathogenicity Studies with Pseudomonas aeruginosa R. E. McCoy ........................ 18
Cadang-Cadang Disease of Coconut: Evidence for a Viroid Etiology J. W. Randles, J. S. Imperial,
P. Palukaitis, T. Hatta and G. Boccardo ................... .......................... 18
Advances in Coconut Cadang-Cadang Research -A. Bigornia, E. P. Pacumbaba, E. P. Rillo
and J. S. Imperial....................... ........................ .. ................ 18
Study on the Origin of the Bunch Rot Disease of Oil Palm (Elaeis guineensis) in Ecuador -
C. Garzo'n Florand E. Mora Carrillo ................ .............................. 19
Determination of the Causal Agent of Spear Rot of Oil Palm (Elaeis guineensis) in Ecuador -
C. Garzon Flor and M. FigueroaN .............................................. 19
Research on the Etiology of Blast of Oil and Coconut Palms M. Dollet ....................... 19
Addresses of Meeting Registrants ................................... ... ............. 20


The 4th Meeting of the International Council on
Lethal Yellowing (ICLY) was held at Fort Lauder-
dale, Florida, August 13-17, 1979. Participating
were eminent scientists from 16 countries who
have specific interest in the coconut palm either
as a world food crop or as an aesthetically im-
portant ornamental tree. In addition, scientists with
expertise in research on plant and animal
mycoplasma-induced diseases participated.
These Proceedings include generalized sum-
maries of the conference and abstracts of the
papers discussed at the meeting.
The ICLY was inaugurated in 1973 at Fairchild
Tropical Gardens during a conference on the
lethal yellowing disease of coconut palms. This 3-
day meeting was unique because it was the first to
bring together scientists of the United States,
Jamaica, Great Britain, and the Food and
Agricultural Organization of the United Nations to
devise a strategy for combating this devastating
disease threatening coconut palms throughout the
world. Since its inception, ICLY has steadily grown
in membership and international participation. A
second ICLY Conference was held at Kingston,
Jamaica in 1975, a third at Jupiter, Florida in 1977
and the fourth in 1979 at Fort Lauderdale, Florida.
The ICLY meetings have been continued bien-
nially because of the benefits that the scientists
working on this difficult disease gain from the
ideas and exchanges of information generated at
these meetings. The world-wide significance of
lethal yellowing is demonstrated by the par-
ticipation of scientists from the major coconut-
growing areas of the world. Also, the importance
attached to this research is reflected in the at-

Fort Lauderdale, Florida
February, 1980

tendance of internationally recognized scientists
from research institutions in the United States,
Great Britain, France and elsewhere. The ICLY-4
meeting was very successful in updating all the
participants on research progress, in generating
ideas on new research approaches, and in iden-
tifying priorities and areas for cooperation.
This meeting would not have been possible
without the sponsorship and liberal financial sup-
port of the City of Fort Lauderdale, the Broward
County Board of Commissioners and the In-
ternational Palm Society. Many other
organizations and individuals made generous con-
tributions and helped make the meeting a suc-
cess. Special recognition is due Mrs. E. M. Rey
who graciously contributed her time to consult
and assist in all aspects of the local arrangements
for the meeting. For all those who contributed to
the support and conduct of this meeting, all par-
ticipants join in expressing sincere appreciation.
Special thanks are due also to the governmental
organizations and others who sponsored the at-
tendance of scientists from the United States and
Copies of the Proceedings may be purchased at
U.S. $5.00 per copy post-paid from the In-
ternational Council on Lethal Yellowing,
Agricultural Research Center, University of
Florida, 3205 S.W. 70 Avenue, Ft. Lauderdale,
Florida 33314, U.S.A. The ICLY is an informal
association of researchers and other concerned
individuals, and those wishing to affiliate with it
should write to Dr. L. Chiarappa, ICLY Secretary,
FAO of the United Nations, Via delle Terme di
Caracalla, 00100 Rome, Italy.

W. B. Ennis, Jr.
Chairman of ICLY-4


S. J. Eden-Green

The International Council on Lethal Yellowing
(ICLY), which was established in 1973, promotes
research on lethal yellowing (LY) and related
diseases that pose a global threat to coconut and
other cultivated palms. The fourth biennial
meeting, which was sponsored by voluntary,
municipal and commercial organizations in
southern Florida, included some 55 papers given
by participants representing 16 countries. Subject
matter ranged from basic biology of mycoplasmas,
which are thought to be the causal agents of LY in
the Caribbean and West Africa, to status reports
on palm diseases associated with unrelated or
unknown agents in South America and the Pacific.
The introduction to the meeting highlighted the
unique contrast between coconut as a world crop,
and in particular its vital role as a source of food
and shelter in developing countries, and the en-
vironmental and commercial value of this and other
palm species as ornamentals in the south Florida
landscape. According to FAO statistics, world
copra production exceeded 5 million tons in
1978, but this figure represents only the amount
entering world trade and takes no account of
coconut products consumed or manufactured
locally. In India alone, it has been estimated that
over half a million people are dependent on the
coir fiber industry. By contrast, in south Florida,
where a recent survey showed that 89% of local
picture postcards featured coconut palms, LY is
estimated to have already caused over US $1
billion in losses to valuable ornamental palms, with
a further $3 million for removal of dead trunks.
Technical sessions commenced with
background reviews on aspects of the basic
biology of "yellows" diseases, their vectors and
the physiology of palms. Experimental data on the
three phases involved in transmission of
mycoplasmalike organisms (MLO) by insect vec-
tors (acquisition, latency and inoculation) were
reviewed by A. H. Purcell. Transmission was
viewed as the product of a sequence of
probabilities, one or more of which could limit the
efficiency of a vector under experimental con-
ditions. These concepts seemed particularly
relevant in view of the difficulty of transmitting LY,
as did an account of anatomical and physiological
features of palms that could affect acquisition and
transmission by vectors (M. H. Zimmermann). Cer-
tain predictions about the distribution of MLO in
palms following infection were made from con-
siderations of phloem transport mechanisms and
pathways; thus inoculation via mature fronds (the

most likely site) would appear to be most likely at
periods of slack turgor, when phloem pressure is
lowest, and would be followed by the trans-
location of MLO to sink sites such as developing
roots, leaves and inflorescences, but not to other
mature fronds. Older leaves would thus appear to
be unlikely acquisition sites for a vector. In the
final paper of this opening session, T. A. Chen
presented a current consensus on the nature and
interrelationships of Mollicutes cultured from plants
and insects. Despite earlier reports which laid
false hopes, only Spiroplasma citri and corn
stunt spiroplasma are universally accepted to be
cultivable plant pathogens. It is, however,
becoming increasingly clear that several other
strains of Spiroplasma, Mycoplasma and
Acholeplasma are widely distributed in flowers
and insects. The better characterized agents in-
clude a spiroplasma pathogenic to honeybees and
other insects (also present in some flowers), and
at least two strains from rabbit ticks, one of which
induces cataracts in suckling mice. Recent reports
(see below) suggest that several other
"yellows" diseases are associated with cultivable
spiroplasmas, but the biological significance of
these organisms is not yet clear.
Original research contributions opened with a
session on disease diagnosis and included two
papers on the application of enzyme-linked im-
munosorbent assay (ELISA) to detect
mycoplasmas in plants and insects. M. Dollet et
al. reported unsuccessful attempts to detect an-
tigens to several Acholeplasma spp. and S. citri
in diseased palm tissues, using techniques that
detected S. citri infection in periwinkle. The
possible etiological role of acholeplasmas in LY
was of particular interest in view of the recent
isolation of these organisms from palms (see
below). In the second report, S. Nome et al.
described the detection of spiroplasma infection
in several hosts, using antisera prepared against
spiroplasmas apparently cultured from aster
yellows (AY) and pear decline (PD) diseased plants.
Weakly positive reactions were claimed using
these antisera against LY-infected coconut tissue
from Florida and Jamaica. If substantiated, the im-
plications of this work will be considerable, and
the results provoked much discussion. Although
differing in biological characteristics, notably trans-
mission and ease of reisolation from plants, both
AY and PD spiroplasmas appear to be
serologically closely related to S. citri, and it was
thus surprising that no reaction was observed

against S. citri antisera included in the tests by
Dollet and co-workers.
Other reports in this session included ex-
perimental studies on translocation in LY-affected
palms (H. G. Basham and F. M. Eskafi) and phloem
ultrastructural changes in palms affected by LY (D.
L.Thomas); two papers by B. H. Tisserat on the
propagation of date palms through tissue culture
and the evaluation of isozymes as genetic markers
in Palmae; the distribution of S. citri in plants and
a description of scanning electron microscopy of
AY spiroplasma (K. Maramorosch).
A session on mycoplasma isolation and culture
commenced with four papers on the charac-
teristics and host distribution of acholeplasmas
and their association with LY diseased coconut
palms, by J. G. Tully, S. J. Eden-Green, P. G.
Markham, R. Townsend, D. B. Archer, and M. F.
Clark. Acholeplasmas were repeatedly isolated
from surface and rotting tissues of diseased palms
in Jamaica, and biochemical, serological and elec-
trophoretic characteristics of over 30 of these
isolates suggested that Acholeplasma axan-
thum, A. oculi, and possibly a new species were
represented. Transmission experiments indicated
that although some of these organisms were well
adapted to multiplication in insects, they were not
transmitted to plants. Antisera prepared against
representative isolates did not react with palm
tissues in ELISA tests, and the reported recovery,
shortly before the meeting, of further isolates from
palms affected by budrot disease (Phytophthora
palmivora) indicated that these oganisms are
probably plant epiphytes or saprophytes.
The isolation and characterization of
mycoplasmas and spiroplasmas from floral sur-
faces (R. E. McCoy and H. G. Basham) suggested
that an even greater diversity of acholeplasma,
mycoplasma and spiroplasma strains are epiphytic
in flowers. Much interest in this session centered
on the claimed isolation and demonstration of
pathogenicity, of spiroplasmas from leafhoppers
that had fed on aster yellows (AY) and Western X
(WX) diseased plants (B. C. Raju et al.). The
authors felt that their successful isolations, which
contrasted with previous failures at several
laboratories, lay in the choice of inoculum and
frequent subculturing to fresh media. The AY and
WX spiroplasmas were serologically and elec-
trophoretically closely related to S. citri, but dif-
fered in biological characteristics, notably plant
host and vector ranges, symptomatology in some
hosts, and their relative difficulty of reisolation
from plants. In view of the wide host range of S.
citri, some participants felt that there was a need
for caution in interpreting these results.
Other papers on mycoplasma isolation and
culture included two reports on the multiplication
of spiroplasmas in wax moth larvae (Galleria

mellonella) and their effect on the growth rate
and survival of this organism, which has potential
as a laboratory model for the study of non-
cultivable agents that infect arthropods; and fac-
tors affecting maintenance in vitro of
pathogenicity, and the long term storage of a non-
cultivable aster yellows agent (A. J. Smith).
Identification of a vector is one of the out-
standing problems in LY research, and mounting
evidence implicating the planthopper, Myndus
(= Haplaxius) crudus* was presented in sessions
on vectors and control. F. W. Howard described a
replicated trial, which followed encouraging
results obtained in a preliminary experiment, in
which some 20,000 adult M. crudus were collec-
ted from diseased areas and introduced to each of
five large cages containing test palms. Five cases
of disease had so far been noted in Veitchia
merrillii palms in four of the cages, with no
disease in five control cages which received the
same treatment without M. crudus. This is the
strongest indication yet that M. crudus is a vec-
tor of LY; the low rate of transmission suggests
that the proportion of insects transmitting in
natural populations from diseased areas is very
low and could explain the failure of earlier ex-
periments. Painstaking efforts to identify a vector
in Jamaica, using leafhoppers (Cicadelloidea) and
palm-feeding Fulgoroidea (A. J. Dabek and H.
Waters) had included a similar experiment, in-
volving about 20,000 M. crudus without ap-
parent positive results. Further transmission work
from the Florida group was reported by J. H. Tsai,
and two more papers by F. W. Howard described
statistically significant reductions over a fifteen-
month period in rates of disease spread and M.
crudus populations following biweekly ap-
plications of diazinon and dimethoate to Veitchia
palms, and correlations between the natural
distribution of M. crudus and the spread of LY in
Other papers on vectors and control included
observations on Macrosteles fascifrons as a
host, but non-vector of the X disease agent (A. H.
Purcell); symptoms produced in plants in response
to injection (A.S. Alivizatos and R. Townsend);
field resistance of Malayan Dwarf (D. H. Romney)
and assessing field resistance to LY in coconut
varieties (B. O. Been); and ornamental palms
resistant to LY for Florida (H. M. Donselman). The
very high field resistance of the Malayan Dwarf,

*Myndus crudus Van Duzee was referred to as
Haplaxius crudus (Van Duzee) in reports presented at
the fourth meeting of ICLY. More recently, J. P. Kramer
(Trans. American Entomol. Soc. 105:301-389)
synonymized Haplaxius Fowler with Myndus Stal. This
nomenclatural change has been incorporated in this

and high or intermediate resistance shown by
other varieties from Malaysia and the Far East,
was the basis of speculative papers by L. Chiarap-
pa on the probable origin of LY and its co-identity
with other wilt diseases of coconut, and a
Malaysian origin of LY (K. Maramorosch). A
coconut disease of unknown etiology in Sumatra,
described by P. Hunt provided further evidence
that coconut diseases with symptoms similar to
LY are endemic in that region. It was suggested
that obvious differences in epidemiology and symp-
tomatology of co-identical diseases in the Carib-
bean and Pacific regions could result from the
selection of a stronger background of resistance
genes in Pacific coconut varieties, together,
possibly, with different environmental or trans-
mission factors. There was, however, some
debate as to whether the bodies recently detect-
ed in diseased coconut samples from Malaysia
resembled MLO and also whether tetracyclines
had caused symptom remission in recently
treated hybrid palms in Indonesia. The differences
in disease symptomatology and epidemiology that
were described were, perhaps, sufficient to
suggest that even if MLO were involved, they
could be unrelated to, or could have evolved in-
dependently from those associated with LY.
The final sessions of the meeting concerned
emerging problems in palm culture, and included
reports on a decline of Phoenix canariensis in
California, associated with Fusarium oxysporum
and Gliocladium vermoeseni (T. V. Feather et
al.); research on the etiology of blast disease of oil
and coconut palm seedlings in West Africa (M.
Dollet); five papers on palm diseases (marchitez,
hartrot, and "Case 9") associated with the
flagellated protozoan Phytomonas; current IRHO
research in Ecuador (M. Dollet); preliminary ob-
servations on control by insecticides and on
varietal resistance in Surinam (V. T. Alexander);
occurrence in coconut palms in Southwest
Colombia (G. Martinez-Lopez et al.); and "Case
9" disease of African oil palm in central Colombia
(R. E. McCoy and G. Martinez-Lopez). A Florida
nurseryman, J. K. Dunaway, advanced a claim that
south Florida's palms (and several other plants)
were being attacked by Pseudomonas
aeruginosa, and offered to sell a secret remedy,
but controlled pathogenicity tests (R. E. McCoy)
showed that this organism was not pathogenic to
palms, even when massive inocula were applied to
internal tissues and tissue cultures. A review of
advances in research on coconut Cadang-Cadang
disease was presented by A. Bigornia et al. and
recent evidence for the viroid etiology of this
disease was described by J. W. Randles et al.
Two reports on the etiology of "Bunch Rot" and
"Spear Rot" of oil palm in Ecuador (C. Garzon Flor
et al.) concluded the scientific presentations.

P. Hunt
ODM, UK/LPTI Sub-Station

The introductory session of ICLY-4 served to
remind us of the diverse role that coconut palms
play in different countries. Lethal yellowing (LY) is
clearly a disease with strong, international im-
plications and perhaps we, as the International
Council for this disease, should consider seeking
funds from an international agency to undertake
necessary research. Presumably basic work will
continue in Florida, but it is not reasonable to ex-
pect the Florida taxpayer to undertake the
development of coconut varieties for commercial
copra production. If LY were to break out in a
country where the coconut is a subsistence crop,
it is very unlikely that such a country could afford
to conduct the research necessary to combat the
disease. Some form of international aid would have
to be sought. I can think of no better organization
than ours to seek international aid and I suggest
we should have a strategy ready.
The majority of the papers in the session on the
basic biology of the yellows diseases, on disease
diagnosis, and on mycoplasma isolation and
culture, did not deal with LY directly. The fact that
the discussions were centered around rickett-
sialike organisms, acholeplasmas, spiroplasmas,
and animal mycoplasmas, emphasizes the
recalcitrance of plant pathogenic mycoplasmalike
organisms (MLO), and especially the
"cocoplasma", to experimentation. However,
despite the many difficulties of LY research, con-
siderable progress has been made in the last two
A rapid and positive diagnostic test for LY was
an area of priority put forward at ICLY-3, and still
remains a high priority. From the encouraging
results presented at this meeting, it would seem
that a serological approach, probably relying on
the sensitivity and selectivity of ELISA, offers the
best hope for the needed test. However, any
refined serology must await the successful culture
of the "cocoplasma" or the development of a
technique for isolating it in quantity.
The culturing of the MLO associated with LY
was another high priority identified at ICLY-3, and
since so much hinges on the culture of this
pathogen, this goal should be the number one
priority in lethal yellowing research for the next
two years. The techniques that have been
described at this meeting for the isolation of the
aster yellows and X disease agents should be ap-
plied to LY using inocula from both palm material


and putative vectors that have fed on diseased
palms. Our newly acquired understanding of the
epiphytic nature of acholeplasmas, spiroplasmas,
and mycoplasmas should warn us of the likelihood
of finding such organisms in attempts to culture
the LY-MLO. The technique of using the wax moth
for the cultivation of spiroplasma is encouraging,
and this insect or others should be tested for their
ability to support growth of MLO.
The most exciting research directly related to
LY presented at the meeting was a report im-
plicating Myndus (= Haplaxius) crudus as a vec-
tor. The results are most convincing and should
stimulate much future work with this fulgorid.
However, we should not stop work on other in-
sects. Results indicate that this insect is an inef-
ficient vector, and perhaps more efficient vectors
exist which so far have eluded us. Researchers in
Jamaica should perhaps use Veitchia palms and
attempt to exactly simulate the conditions of the
successful Florida transmissions to determine
whether M. crudus is a vector of LY in Jamaica.
Myndus crudus should also be used in attempts
to transmit LY to other plants such as periwinkle.
The establishment of a MLO-free insect colony
would be useful in such experiments to overcome
the possibility of field-collected insects harboring
other MLO.
An additional priority of ICLY-3 was to intensify
breeding and screening for disease resistance in
palms. The breeding and screening of hybrids and
varieties of coconuts in Jamaica continues, and
there is substantial data available on their com-
parative resistance. It appears that there are many
coconut varieties and hybrids with adequate
resistance against LY that have potential utility as
ornamentals in Florida. For other palm species,
Florida workers should possibly select or breed
from the survivors of the LY attack.
The papers on the protozoan diseases of palms
and the Natuna disease, as well as references to
red ring and palm diseases of unknown etiology in
Southeast Asia and the Pacific, emphasize the
inadequacy of symptomatology as a diagnostic
tool. It was hypothesized that LY originated in
Southeast Asia and may exist now as several
strains throughout the world. It therefore seems
desirable to screen varieties against the various
pathogens causing coconut diseases of uncertain
etiology. This is especially important for varieties
being considered for breeding purposes or for in-
troduction to other parts of the world.Locations

such as the Caribbean, West Africa, India,
Southeast Asia, and the Pacific should be used,
and a large number of varieties should be tested.
Such a program would have to be funded by an in-
ternational organization such as FAO, but perhaps
it would be appropriate for ICLY to make the
proposal. With reference to the protozoan
diseases, the differential responses of coconut
varieties to hartrot in Surinam offers hope for af-
fected areas in South America. These trials should
be expanded and replicated in other countries as
At ICLY-3 a proposal was made to concentrate
effort in identifying hosts other than palms that
might carry the LY agent. However, until a means
of transmission is perfected or a specific
diagnostic test for the LY organism is developed,
this is an almost impossible goal.
Increased research on the physiology of
diseased palms was also designated as an area of
priority at ICLY-3. Since then some interesting ob-
servations have been made on the water relations
of palms with early symptoms, but we are still a
long way from understanding the disease
physiology of LY. Basic research in this field
should be continued.
Representatives of the International Palm
Society made a plea at ICLY-3 for methods of
verifying that LY cannot be spread by seed and of
assuring that healthy palms do not harbor the LY
pathogen. Unfortunately, present technologies of
disease diagnosis are not sensitive enough to
determine low percentages of infection, so at the
present time a positive statement cannot be made.
There is no indication from past research that LY
is seed transmitted or that the pathogen can
remain latent in healthy palms.
Areas of LY research that receive top priorities
for the next two year period should include the
1. Intensification of efforts to culture the MLO
from LY palms and suspected vectors.
2. Expansion of transmission studies with M.
crudus but continuation of investigations with
other candidate vectors.
3. Development of a reliable diagnostic test
for the LY agent.
4. Use of surviving ornamental palms in
Florida as sources for seed and breeding of
resistant varieties.

L. Chiarappa and P. Poetiray
FAO of the United Nations

The main purpose of this paper is to stress the
importance of the coconut palm in world
agriculture where this crop is valued for purposes
other than its ornamental use. The potential impact
of a disease like lethal yellowing must be
measured with this in consideration.
The total world area devoted to coconut produc-
tion is not known with certainty, but FAO con-
servatively estimates it to be over 6 million hec-
tares. Although approximately 90 per cent of this
area is in Asia and Oceania, coconuts are grown in
one form or another in most of the islands and
tropical coastal regions of Central and South
America, the Caribbean, and Africa. The produc-
tion statistics for these regions are based only on
copra entering world trade; thus there is no exact
figure to indicate the percentage of coconut
production that is consumed fresh or is locally
processed into other products. Total world copra
production entering international trade is now
estimated to be over five million metric tons per
annum and the trend in recent production is
shown in Table 1. In general, the world supply of
copra tends to remain fairly stable with any in-
creases in production offset by local consumption.
Prior to World War II, copra and coconut oil were
among the most important internationally traded
commodities because of their use in the manufac-
ture of soap, margarine and explosives. Since then
their relative importance has slightly decreased,
mainly because of the strong research and
marketing efforts in other oil producing crops such
as soybean, sunflower, and oil palm. This relation-
ship is shown in Table 2.
Table 1.
1969-71 1976 1977 1978

Latin America
Far East
Other Countries
World Total




sudden "green revolution" in coconut production
with a dramatic increase in acreage or in produc-
tion per unit area. Although rapid increases in
production are not anticipated, coconut growing
will continue to be important to world agriculture in
ways that are not reflected in world trade
Table 2.
(1,000 MT)
1946-66 1972-74 1977-78

2. Sunflower
3. Oil palm
4. Groundnuts
5. Cottonseed
6. Coconut
8. Olive
9. Palm kernel
10. Others





21,750 30,640 34,050

It is estimated that over fifty percent of the
world's coconut crop is consumed fresh. This
means that in tropical countries coconuts are very
important in the diet of millions of people who live
at a subsistence level. In addition coconut cake is
a valuable source of cattle and poultry feed which
in turn are important sources of meat, milk and
eggs in developing countries. Another important
product derived from coconut is "toddy", the
sweet juice which is tapped from coconut in-
florescences. This is fermented to produce
alcoholic beverages such as arrack or to produce
coconut vinegar. Both of these products are major
contributors to local revenues. Coconut oil is
valued because it belongs to the group known as
lauric oils that have a high proportion of glycerides
of lower fatty acids. It is among the least variable
of commercial fats and is preferred to other oils for
many edible products and for non-food uses such
as the manufacture of soap, glycerol, illuminating
oil and synthetic detergents. Desiccated coconut
is used in candy, cookies and cakes by the con-
fectionery and bakery industries.
The coconut palm is the source of many ad-
ditional products that are either important to local
economies or to the domestic life of inhabitants in
coconut growing countries. Coir fiber and coir


3,829 5,072 4,722 5,045

Pre-war World Copra Production = between
2,400 and 3,100 (1,000 MT).

While the other important oil crops are mostly
suited to large monocultures, coconut plantations
are and will remain a small-holder's crop for the
foreseeable future. Therefore we cannot expect a

products, derived from the husk of the coconut
fruit, form the bases of numerous small industries
that provide employment for many. For example,
over half a million people in the State of Kerala in
India are economically dependent on the coir in-
An estimated three million tons of coconut shells
are produced annually and are used for making
such things as drinking bowls, latex collecting
cups, scoops and smoking pipes. Shells are also
used as a fuel supply either directly or as charcoal.
This charcoal is a good raw material for the
production of activated carbon used for gas ab-
sorption, for bleaching, and for similar chemical
The trunk of the coconut palm is used for
building sheds and other structures. Leaves are
used for thatching or for making screens. The
midribs of leaflets are used for the construction of
lobster and fish traps or for making stiff brooms.
Coconut roots are utilized medicinally in decoc-
tions against fever or dysentery and are also used
in making mouth washes and gargles. These roots
can serve as toothbrushes when they are frayed
Certainly coconut contributes much to the sup-
port of life for many people, but its full importance
can only be assessed in light of other con-
siderations. Coconut palms can often grow and
produce in areas where no other crops can grow;
they are long-lived and need neither the care nor
the managerial skill required by other crops; and
the processing into copra, oil or cake requires
only simple, inexpensive tools which villagers
themselves can produce. This makes the coconut
ideal for subsistence farming.
Because coconut production can be achieved
with minimal inputs, little effort was expended in
the past to improve cultural practices or varieties.
In the 1930's Burkill (1) stated that "Nature gave
the coconut to man ready made, whereas
whatever excellence is possessed by most of his
other important food plants has been his reward
after ages of semi-conscious selection". This
opinion has changed substantially in recent years.
Coconut culture is well suited to considerable
modernization that would increase production.
This enhanced production would contribute
toward the solution of one of the many problems
of underdevelopment in the tropics. The revival of
interest in coconut production is reflected in-
ternationally through increased research for
coconut genetic improvement and improved
cultivation. FAO has greatly assisted in this en-
One of the most intractable problems to world
coconut production is that of coconut diseases
with undetermined or poorly-understood
etiologies, and of these, lethal yellowing is

probably the most serious. The International
Council on Lethal Yellowing was formed to help
promote international cooperation and coordinate
international efforts in finding solutions to these
disease problems. The results of the ICLY
meetings therefore have great significance
throughout the world where the coconut is the
"tree of life".
(1) Burkill, I. H. 1935. A dictionary of the economic
products of the Maylay Peninsula. Crown Agents, Lon-
don. (Reprinted 1965).

H. Romney, Coconut Industry Board, Jamaica.
Growing plantation palms requires tropical tem-
perature, adequate rainfall, good rooting space
and good farming practices. Factors to be con-
sidered are: (1) Choose a variety which is uniform-
ly high yielding, early bearing and resistant to
local pests and diseases. Since Tall varieties are
out-pollinated, mother-palm selection brings about
little improvement. Malayan Dwarf and its F1
hybrids begin to bear earlier than Tails, making
them a profitable choice. No new variety or hybrid
should be planted commercially until tested. Seed
production should be carried out by a responsible
agency. Plants should be always available, so that
the farmer is not tempted to use his own seed. (2)
Plant at the optimum density, i.e. 110-125
palms/acre for Malayan Dwarf and 75-85
palms/acre for Maypan hybrid. The higher den-
sities are used on poor soil or sunny sites, since
adjacent palms compete primarily for light. With
palms at lower densities, weed control costs in-
crease. Planting on a triangular rather than a
square layout increases palm density by 13%. (3)
Remove shade. Shade can retard onset of bearing
by 2 years and reduce yield of bearing palms sharp-
ly. (4) Control weeds. Weeds compete strongly
with palms, especially for moisture during dry
weather. The susceptibility of palms to
phenoxyacetic acid and related herbicides should
be recognized. (5) Fertilize. Most palms show an
economic response to N and K, and some soils
are deficient in Cl, Mg, S or Na. Potassium has an
effect on reducing leaf spot. There is a low in-
teraction between weed control and fertilizing.

Donselman, University of Florida, USA.
Southern Florida is the only area on the U.S.
mainland where coconuts and many other tropical
palm species can be grown. They are essential to
the tropical landscape that makes this region
unique. Lethal yellowing (LY) has destroyed a
large proportion of these palms. The potential im-
pact of LY on the environmental quality and on the
aesthetic appearance of southern Florida is

Moderator: R. E. Davis

PATHOGENS. A. H. Purcell, University of Cali-
fornia, U.S.A.
Understanding how certain insects transmit
plant disease agents can improve our recognition
of other vector-pathogen relationships and of the
reasons why some insects are efficient vectors of
these agents and others are not. A great diversity
of microorganisms are totally dependent upon in-
sects as hosts. In such cases, the microorganisms
are transmitted 'vertically' from parent to offspring
as in the sex-ratio organism of Drosophila, or
'horizontally' from insect to insect, as in the ter-
mites. Vector-borne plant pathogenic
microorganisms use plants as intermediaries for
horizontal transmission. The transmission process
in insects can arbitrarily be subdivided into three
consecutive phases: acquisition, latency and
inoculation. A number of aspects of the processes
in each phase can either promote or preclude suc-
cessful transmission. In the acquisition phase, for
example, the site, mode and duration of feeding,
host plant species, age of infection in the source
plant, temperature and seasonality can all directly
influence whether or not the pathogen is taken up.
The latency and inoculation phases can be
analyzed in a similar fashion. The net efficiency or
probability of transmission for any vector (or non-
vector) species can be interpreted as the product
of a chain of probabilities assigned to the
necessary components of the entire transmission

IN PALMS. M. H. Zimmermann, Harvard Forest,
The development of a disease often depends
largely upon translocation within a plant. Not only
the pathogen, but also its metabolites, may be
moved about within the plant. Investigation of
long-distance transport must begin with an
analysis of the layout of the plumbing system.
Although we have analyzed the vascular system
of the coconut palm partially, our knowledge is by
no means complete and we must depend upon
knowledge gained from the many other palm

species that we have investigated. Infection
probably takes place in a mature leaf; phloem trans-
port would then take the mycoplasmalike
organisms (MLO) to the roots on the one hand,
and to the developing inflorescences, fruits,
growing leaves and the apical meristem on the
other. The pathway to the apical meristem in large
palms is via a direct, more or less peripherally-
located pathway, and an indirect, more centrally-
located pathway. In small palms MLO transport is
probably only via the short path. When the apical
meristem is damaged the disease has become
fatal. Tetracycline injections can only be suc-
cessful so long as the apical meristem is intact.
Available evidence makes it very unlikely that MLO
are xylem-mobile, hence MLOs have no track into
mature leaves and foliar yellowing must be due to
xylem import of a toxic metabolite.

AND INSECTS. T. A. Chen, Rutgers University,
During the past 9 years, several spiroplasmas
have been isolated and cultured from yellows-
diseased plants, healthy plants, insects and ticks.
Spiroplasma citri and the corn stunt spiroplasma
have been proved to be plant pathogens.
Honeybee spiroplasmas have been shown to
cause a newly described disease of bee, and the
suckling mouse cataract agent can induce
cataracts in newborn mice or newborn rats. The
etiological association of spiroplasmas isolated
from several other yellows-diseased plants is not
clear because suitable vectors have not been
found. Recently, spiroplasmas and mycoplasmas
have been either observed or successfully
isolated from various flowers and insects, in-
dicating their wide range of habitats. Serological
tests and biochemical studies have demonstrated
that some of these isolates are closely related,
while others are quite different. Additional in-
vestigations of the natural occurrence of
spiroplasmas and mycoplasmas could contribute
to an enhanced understanding of the ecology of
these wall-free prokaryotes.

Moderator: D. L. Thomas

AFRICA. M. Dollet, C. Saillard, O. Garcia-Jurado,
J. C. Vignault and D. Gargant, IRHO/GERDAT,
France; J. G. Tully, National Institute of Allergy
and Infectious Diseases, USA; and J. M. Bove,
INRA, France.
Serological tests by the ELISA method were
carried out on samples of inflorescences and
roots from diseased coconuts from Togo. The
samples came from three diseased coconut palms
with (1) the early symptom of nut drop, (2)
yellowing of the lower leaves or (3) overall
yellowing, and from a healthy control palm in an
uncontaminated zone. The inflorescences had the
characteristic symptoms associated with the
presence of mycoplasmalike organisms (MLO).
The samples were tested against antisera of the
following strains: Acholeplasma axanthum S
743, A. oculi, A. modicum, A. granularum, A.
laidlawii PG 8 and Spiroplasma citri R8 A2.
The plant controls were Spiroplasma citri in-
fected and healthy periwinkles (Catharanthus
roseus). Only the periwinkles infected with
Spiroplasma citri gave a positive ELISA test with
the corresponding antiserum. Checks for possible
inhibition of the serological reactions by oxidation
of the ground coconut tissue were made by add-
ing grindings of healthy or diseased coconuts to
(1) sub-cultures of A. axanthum and A. laidlawii
cultures and (2) purified antigens of the different
strains of mycoplasma tested against their an-
tiserum. The results are discussed. Electron
microscopic examination of the phloem from these
same inflorescences revealed the presence of
low concentrations of MLO.

YELLOWING. H. G. Basham and F. M. Eskafi,
University of Florida, USA.
Evidence suggests a reduction in water trans-
port in palms with lethal yellowing (LY). Other
workers have reported reduced dye movement,
root damage and reduced leaf water potential in
palms with LY. We have found that the upward
directed transport of 32-P through roots, stems
and leaves in palms with LY is much less than that
in healthy palms. When the stem of a healthy palm
was injected with 1 mCi of 32-P, the activity in 1.5
cm leaf disks averaged > 100 CPM 30 min after
injection. Activity in leaf disks from a palm in an
early stage of LY was negligible for the duration of
the experiment (5 days). In other experiments,
significantly less xylem flow in diseased palms

was noted when isotope was supplied by root up-
take or injection into the rachis. Secondary roots,
which appeared healthy on visual examination,
were excised from a LY-diseased palm and their
tips placed in a 32-P solution. Uptake by these
roots was four-fold less than that by roots excised
from healthy palms. Stomata on green leaves of
diseased palms are generally ,closed, even at
times of the day when stomata on healthy palms
are open. These data suggest that xylem flow is
severely limited in palms with LY even in the early
stages of visible symptom development.

LETHAL YELLOWING. D. L. Thomas, University
of Florida, USA.
Mycoplasmalike bodies (MLB) were observed in
the sieve elements of 23 species of palms that
were dying from suspected lethal yellowing in-
fection. Some of the sieve elements from
diseased palms appeared normal except for the
presence of MLB. However, in many of the sieve
elements from infected tissues, the MLB were
dispersed in matrices which were not seen in con-
trol material. One matrix type varied in electron
density and had an amorphous to granular struc-
ture. A second matrix type, of moderate electron
density, had a definite fibrillar structure that
closely resembled P-protein. A distinct parietal
zone of clustered ribosomes often surrounded the
matrices. The presence of ribosomes in otherwise
mature sieve elements suggests an abnormal dif-
ferentiation in diseased phloem tissues. Sieve
elements from diseased palms appeared to un-
dergo a premature degeneration. The sieve
element contents, including MLB, became in-
creasingly electron-dense and lost ultrastructural
detail. At intermediate stages of degeneration,
MLB membranes and sieve element matrices
were barely discernible. In advanced stages of
degeneration, sieve elements were crushed and
their contents were electron-opaque. All stages of
phloem degeneration were commonly found in in-
dividual palms.

USDA, US Date and Citrus Station, USA.
The date palm (Phoenix dactylifera L.) is an
arborescent monocot that can be clonally
propagated on a limited scale by offshoots. Large
scale, rapid propagation of clonal date palms was
attempted by tissue culture. Asexual plantlets
were obtained from lateral buds, shoot tips, stem
and rachilla pieces, and excised embryos. Date

palm explants produced callus which was cultured
on a modified Murashige and Skoog medium con-
taining 3 mg/I of N-(A2-isopentyl)-adenine, 30
mg/I of 2, 4-dichlorophenoxyacetic acid and 3
g/l of activated charcoal. Transfer of callus to a
medium devoid of hormones enhanced the for-
mation of plantlets. Plantlets arose from callus
through an asexual embryogenesis process which
closely paralleled the zygotic development. Plant-
lets have been transferred to soil and are free-

PALMAE. B. H. Tisserat, USDA, US Date and
Citrus Station, USA.
Several polymorphic gene-enzyme systems
have been examined in the genus Phoenix with
the aid of starch gel electrophoresis. The genetic
control of leaf isozymes of alcohol
dehydrogenase, esterase, glutamate oxaloacetate
transaminase, phosphoglucose isomerase and
phosphoglucose mutase was studied. Genotype
material of seedling populations and their parents
came from a USDA date breeding project initiated
in 1948. The five enzyme systems were specified
by seven genes with 14 alleles, and the
segregation ratios of the parents and progeny
followed a predictable Mendelian inheritance. For-
ty-six female and 20 male date cultivars were
genotyped to provide single gene markers for the
date palm. Each cultivar showed distinctive
isozyme patterns. Isozyme composition may be
used with present taxonomic procedures to con-
firm the identities of cultivars. Polymorphic gene-
enzyme systems may be used for taxonomic and
genetic studies of Phoenix.

Best and K. A. Plaskitt, John Innes Institute, UK.
Enzyme-linked immunosorbent assay (ELISA)
has been used to detect Spiroplasma citri an-
tigens in artificially infected periwinkle. Periwinkle
stems were infected with S. citri by grafting, and
at intervals over a period of weeks, samples of
grafted shoot, ungrafted shoot and root were
taken and the amount of spiroplasma antigen in
the tissues estimated by ELISA. This was then
related to spiroplasma numbers by comparison
with ELISA tests on cultures. Spiroplasmas were
detected in the grafted shoots 5 days after graft-

ing, in ungrafted shoots after 8 days, and in roots
after 14 days. The appearance of S. citri in roots
coincided with a decline in the numbers of
spiroplasmas in the shoots. Electron microscopic
examination confirmed these findings. In shoots,
there was an exponential increase in spiroplasma
numbers to a maximum of 109 cells per gram of
tissue at fourteen days after grafting. This was
followed by a decline in numbers to about 106
cells per gram of tissue at twenty-eight days after
grafting. The number of spiroplasmas in roots
reached over 109 per gram of tissue and no
decline in numbers was observed for the duration
of the experiment.

Maramorosch, Rutgers University, USA.
The aster yellows spiroplasma ATCC 29747,
originally isolated in 1975 from naturally infected
lettuce and stored in liquid nitrogen (Kondo et al.,
1977) can be grown in liquid media or on agar.
Light and transmission electron micrographs
revealed a striking resemblance between ATCC
29747 and Spiroplasma citri. In liquid media,
helical and non-helical forms, as well as ring-like
structures and branched filaments were
predominant. On agar media typical fried-egg
colonies were formed. To determine the mor-
phology of the aster yellows spiroplasma on semi-
solid media, colonies were fixed in 3%
glutaraldehyde in 0.1 M cacodylate buffer,
dehydrated, and critical point dried. Scanning
electron microscope examination of gold-coated
specimens revealed that most colonies consisted
of rounded or elongated bodies in the center of a
colony and of a mycelium formed at the colony
periphery. In older colonies spiral forms were en-
countered and in rare instances twisted and
corkscrew forms were observed (Maramorosch,
1979). Connections between colonies were form-
ed by strands of the mycelium. Obviously the
ability to form spirals is an inherent characteristic
of members of the Spiroplasmataceae that can be
manifested not only in liquid but also in semi-solid
media. The beading and budding, frequently seen
in older colonies grown in broth, resembled forms
observed in the phloem of aster yellows-infected
plants. The aster yellows spiroplasma is con-
sistently associated with a rod-shaped, virus-like
particle that resembles the S. citri virus SpV-1
(Liss & Cole, 1979).

Moderator: S. J. Eden-Green

National Institute of Allergy and Infectious
Diseases, USA.
The acholeplasmas are a group of mycoplasmas
currently receiving unusual interest because of
their recent and repeated recovery from plants.
Their most distinctive property, a characteristic
which separates them from most other
mycoplasmas within the class Mollicutes, is their
lack of sterols as a growth requirement. At least
seven serologically distinct species have been
established within the genus Acholeplasma.
There are still problems in the classification of
these organisms, primarily because there are a
minimum number of unique biochemical markers
within the group, and technical difficulties arise in
preparing potent and specific antisera to individual
members. The distribution of acholeplasmas in
animal hosts is very extensive, with a few species
being found in almost all animal hosts examined.
Other acholeplasmas have been identified only in
a rather limited host range and only in specialized
tissues. On the basis of information obtained in
earlier studies (during 1935-40), which demon-
strated the occurrence of these organisms in
sewage and soil, they were considered to be true
saprophytes. This concept was modified in later
years when acholeplasmas were found frequently
in animal hosts, and their presence in soil was at-
tributed to contamination with animal excreta. The
recent isolation of these organisms from plantS'
where contact with vertebrate hosts is unlikely,
suggests that a return to the earlier concept of
these organisms as saprophytes might be in or-
der. The role of insect vectors in the transmission
of acholeplasmas from animal to plant sources
now poses a major question to be resolved in the
understanding of the epidemiology of the

Green, ODM Coconut Lethal Yellowing Team,
Jamaica; J. G. Tully, National Institute of Allergy
and Infectious Diseases, USA; and R. Townsend,
John Innes Institute, UK.
Since the reported isolation of Acholeplasma
axanthum from coconut phloem sap at ICLY-3,
more than 30 additional Acholeplasma isolates
have been recovered from crown tissues of
coconut palms affected by lethal yellowing (LY).

The highest isolation rate, 33% of samples from
two palms, was obtained by filtering macerated
palm tissues through 0.65)Jm pore filters into con-
ventional mycoplasma media supplemented with
10% serum, 0.01% Tween 80 and 0.1% bovine
albumin. No isolates were recovered from the
same batches of media inoculated via 0.22 um
filters. Most isolates were derived from decaying
tissues at the bases of expanded leaves and in-
florescences, and from rotting internal immature
leaf tissues. Several isolates were also recovered
from epidermal tissues scraped from the bases of
expanded leaves or spathes, and two were from
apparently healthy tissues. Metabolic and
serological tests on the uncloned isolates in-
dicated that about two thirds were strains of A.
axanthum and most of the remainder were
related to A. oculi. Gel electrophoresis protein
banding patterns showed general agreement with
these results, but suggested considerable
variation within the serological groups. These
results demonstrate that at least two
Acholeplasma species are associated with LY
diseased palms, either as epiphytes, saprophytes
or pathogens.

J. Eden-Green, ODM Coconut Lethal Yellowing
Team, Jamaica; P.G. Markham and R. Townsend,
John Innes Institute, UK.
Potential transmission of acholeplasmas to plants
was examined by monitoring the multiplication
of isolates injected into "yellows'.' disease vec-
tors. In preliminary tests using Dalbulus maidis,
two isolates attained titres of 108 colony forming
units (cfu) per insect in all insects sampled within 7
days of injection, but three other cultures per-
sisted or multiplied in only a few individuals. Twen-
ty-five isolates were subsequently tested
following injection into Euscelidius variegatus
and about a third multiplied to titres of ca. 108 cfu
per insect. These included representatives of both
the A. axanthum and A. oculi groups. Other
isolates declined and died in most leafhoppers but
sometimes persisted or multiplied in a few in-
dividuals. In some of these instances multiplication
or decline appeared to be related to the dose of
organisms injected. Repeated experiments with
representative cloned and uncloned isolates gave
consistent results. There was no evidence that
acholeplasmas were transmitted to plants on
which injected insects had fed; one transmission

was noted following membrane feeding on
sucrose solution but this could not be repeated.
Leafhoppers allowed to feed through membranes
on acholeplasma suspensions did not acquire
these organisms in a persistent manner. The
results suggest that acholeplasmas are well adap-
ted to multiplication in leafhoppers, probably in the
hemolymph, but are not readily acquired or trans-
mitted by them.

nes Institute, UK; S. J. Eden-Green, ODM
Coconut Lethal Yellowing Team, Jamaica; P. G.
Markham, D B. Archer and M. F. Clark, John Innes
Institute, UK.
More than 40 Acholeplasma isolates from
lethal yellowing-diseased palms have been
examined by one dimensional polyacrylamide gel
electrophoresis. Three groups could be identified
on the basis of pattern homology. Isolates in group
1 had many bands in common with A. axanthum,
while those in group 2 showed an entirely dif-
ferent pattern which had some similarities with A.
oculi. Group 3 comprised a single isolate whose
pattern was different from any of the seven
Acholeplasma type strains. This classification by
gel pattern was supported by evidence from
fluorescent antibody studies. Positive reactions
were observed between antiserum to A. axan-
thum and all group 1 isolates tested. Very weak
positive reactions occurred between group 2
isolates and antiserum to A. oculi. Triply filtered
clones derived from all isolates gave similar
results. Four representative clones were selected
for DNA hybridization studies. Preliminary results
showed significant homology between DNA from
A. axanthum and the two group 1 clones, but lit-
tle homology between DNA from A. axanthum,
A. laidlawii, A. oculi or A. granularum and the
clones from groups 2 and 3.

E. McCoy and H. G. Basham, University of Florida,
Six undescribed mycoplasma isolates were ob-
tained from floral surfaces of tropical and sub-
tropical plants in south Florida. These include five
non-helical forms (1. isolate L1 from Citrus
limon, 2. isolate GF1 from Citrus paradisi, 3.
isolate PP1 from Calliandra haematocephala,
4. isolate M1 from Melaleuca leucodendron
and 5. isolate S01 from Grevillea robusta,) and
one helical form (isolate PPS1 from Calliandra
haematocephala). All isolates have been triple

cloned and tested for growth at 30 and 37 C,
growth in serum-free media and growth in the
presence of arginine and digitonin. Colony mor-
phology, organism form and growth rates were
determined. Comparisons between isolates and
several previously described mycoplasmas have
been made with serological procedures (growth
inhibition, ELISA, radial diffusion and Ochterlony
tests) and by protein patterns determined by gel
electrophoresis. Results indicate that L1, GF1,
and PP1 are in the genus Acholeplasma and are
closely related to one another. M1 and SO1 are in
the genus Mycoplasma. PPS1 is a member of
the genus Spiroplasma and is distinct from the
only described species of the genus,
Spiroplasma citri. The presence of a range of
mycoplasma types on the flowers of several plant
species indicates that these organisms may be
rather widespread in nature.

COCONUTS. S. F. Nome, Consejo Nacional de In-
vestigaciones Cientificas y Tecnicas, Rivadania
1917, Buenos Aires, Argentina; B. C. Raju and G.
Nyland, University of California, USA.
The ELISA technique has been used to detect
spiroplasma infections in peach, cherry, pear, her-
baceous hosts and insects, and to detect lethal
yellowing (LY) infection in coconut samples from
Florida and Jamaica. Antisera prepared against
previously cultured spiroplasmas from plants af-
fected with aster yellows and pear decline were
used in our studies. Coconut meristem tissue was
macerated in a blender with phosphate buffered
saline (PBS) solution and subjected to low speed
centrifugation. The supernatant was centrifuged at
high speed and the pellet, resuspended in PBS
and Tween, was sonicated. Five>ug of 7-globulin
was used for coating micro-ELISA substrate
plates which were incubated for 4 hr at 36 C.
Coconut samples were added and kept for 1 8 hr
at 6 C. Enzyme labeled c/-globulin (alkaline-
phosphatase type VII; Sigma Chemical Co.),
diluted at 1 /500, was added and left for 4 hr at 36
C. The reaction with the substrate (p-nitrophenyl
phosphate; Sigma Chemical Co.) was ac-
complished at room temperature for 50 min.
Visual color reaction was observed after 30 min
and photometric measurement at 4.5 nm was
taken after 50 min. The E405 values for LY infected
coconut, using antiserum prepared against the
spiroplasma associated with pear decline, were
2.5 times higher than control values. No visual
color reaction was observed with healthy coconut
prepared the same way as diseased coconut. The
same technique might be of use in screening
possible host plants and vectors for the LY agent.

LONELLA (L.) R. E. McCoy, University of
Florida, USA; and M. J. Davis, Rutgers University,
Larvae of the Greater Wax Moth, Galleria
mellonella (L.) supported extensive multiplication
of several spiroplasma strains when injected with
2 Aul doses of spiroplasma broth cultures.
Spiroplasma multiplication in the insects was
monitored by darkfield examination of small
hemolymph samples taken by needle puncture.
Galleria are readily reared on an artificial medium
in the laboratory and have a wide temperature
range for growth. The life cycle is complete in less
than 2 weeks at 35 C. Multiplication rate of the
spiroplasmas in larvae hemolymph varied with the
spiroplasma strain injected. S. citri, G1 and SR3
spiroplasmas reached titers of ca. 108 spirals per
ml hemolymph after 7-10 days at 30 C, but
spirals were not detectable in hemolymph until at
least 48 hours after injection of these isolates.
However, the flower isolates 23-6 and PPS1
multiplied rapidly with titers approaching 107
organisms per ml hemolymph 12 hours after in-
jection and reaching 109 by 24 hours. Titers
remained at these levels for the life of the larvae,
and spiroplasmas were present in adult moths af-
ter pupation. Spirals observed in hemolymph were
short, active, and had one to three turn helices
without blebs or other degenerative signs.
Galleria mellonella has proven to be a good
host for a number of identified spiroplasmas. We
feel that this insect has potential to serve as a tool
for further studies of spiroplasma pathogenicity
and culture technique.

R. V. Dowell and R. E. McCoy, University of
Florida, USA.
Two .ul aliquots of the following media-grown
spiroplasmas were injected into 0.04 0.06g wax
moth larvae: Spiroplasma citri, SR 3, PPS1, G1
and 23-6. There was a direct relationship between
larval weight gain and survivorship. There was an
inverse relationship between spiroplasma titer and
weight gain, and between titer and survivorship.
The three spiroplasma isolates from flowers
(PPS1, 23-6, SR3) were highly pathogenic to the
host larvae. All adult moths issuing from infected
larvae were also infected.
cell and G. Nyland, University of California, USA.
Macrosteles fascifrons (Stal) and
Colladonus montanus (V.D.) were fed on Plan-
tago with aster yellows and on celery with X

disease, respectively. Three different strains of
aster yellows (DAY, SAY, TLAY) and the peach
yellow leaf roll strain of X disease were used.
Helical, motile, cell wall-free spiroplasmas were
isolated in cell-free medium (ME-1) from these in-
fective insects. No spiroplasmas were isolated
from leafhoppers fed on healthy plants. Twenty-
five to 50 insects were surface sterilized with
sodium hypochlorite, rinsed in sterile distilled
water and cut into small pieces in 20-25 ml of
broth medium. The medium was then passed
through a 0.45.,m membrane filter. Two-tenths
ml of this inoculum was added to 10 ml of broth
medium and incubated at 27-28 C. Subcultures in-
to fresh broth medium were made after 2 days.
Spiroplasmas were observed in the first sub-
cultures, but not in the primary inoculum, after 16-
22 days of incubation. All the isolates formed
"fried-egg" type colonies on agar medium. The
organisms survived at 36 C for 2 days, but not at
38 C or higher. Serological relationships of the
cultured organisms with other spiroplasmas were
studied by agar gel double diffusion, growth
inhibition and spiral deformation tests.
Serologically the isolated spiroplasmas were
closely related to Spiroplasma citri, but not to
the honeybee or tulip tree spiroplasmas (obtained
from R. E. Davis).

Smith and R. E. McCoy, University of Florida, USA.
Macrosteles fascifrons insects were allowed
to feed on aster yellows (AY) diseased asters for
3 weeks and then were collected and placed in-
side an air-tight container and frozen at -40 C. At
intervals up to two years, insects were recovered
and ground in a glycine-MgCI2 buffer at pH 7.5
and 600 mOs, giving a 10-2 dilution of insect to
buffer. Healthy Macrosteles fascifrons were im-
mediately injected with this extract and placed on
healthy asters. The inoculated plants were main-
tained at 27 C and typical AY symptoms appeared
within 15-30 days. These results confirm those of
Chiykowski (Can. J. Micro. 23:1038, 1977) on
long term storage of the AY agent.

A. J. Smith, University of Florida, USA.
In vitro longevity of the aster yellows (AY)
agent, isolated from the insect vector
Macrosteles fascifrons, was determined by an
infectivity assay. Insects were fed on diseased
asters for a minimum of 7 days, collected, and
ground in an isolation medium. The extract was in-
jected into healthy insects after it had incubated at
27 C for 0, 4, 8, 12, 24, 48, 72, 96 or 120 hours.
The isolation media were based on a glycine-

MgCI, buffer, the pH was varied between 6.5 -
8.0 at 0.25 unit intervals, and osmolarity was
tested at 400, 600, 800, 1,000 and 1,200 mOs.
The effects of various concentrations of spermine
and of sodium thioglycolate (a redox reagent)
were tested on longevity. Longevity in vitro was
greatest with a pH range of 7.0 7.5 at high

osmolarity (1,000 mOs). At pH values greater
than 7.5, regardless of osmolarity, survival of the
AY agent was minimal. The addition of the redox
reagent did not measurably affect survival,
whereas maintenance was increased from 48 to
72 hours with the addition of spermine.

Moderator: J. H. Tsai

PALMS IN JAMAICA. F. M. Eskafi, University of
Florida, USA.
Radioactive isotope 32-P was used to label 45
healthy non-bearing Jamaica Tall coconut trees
in Jamaica from January 15 to May 15, 1979 in
Caenwood during the dry season and in Plantain
Gardens during the rainy season. About 10,000
homopteran insects were trapped on and around
these palms by sticky, light, yellow and cone
traps. These homopterans were placed on X-ray
films daily for initial screening, and after 3 days of
exposure, the labeled insects were analyzed with
a gas-flow counter for radioactivity.
Autoradiographs of labeled insects were
evaluated by assigning a 1-10 visual index of in-
tensity. Homopterans were also collected by a D-
vac insect sampling machine from the un-
dergrowth and vegetation in the vicinity of the
coconut palms and were caged on radiolabeled
coconut leaflets. Among the insects which fed on
palms and which were caught in traps, 22 species
and seven genera have been tentatively identified,
and five specimens are unknown. Ten insect
species and one insect identified to genus fed on
radiolabeled leaflets when confined. The total
number of labeled insects of each species collect-
ed ranged between 1-26, with their radiation be-
tween 17-235 counts per minute; background
counts were between 12 and 38. Some species
that had high radioactivity have not been tested in
lethal yellowing transmission studies, or not
adequately tested. These include Dawnaria sor-
didulum (Muir), Idioderma varia (Van Duzee)
Typhlocybella minima (Baker), T. maculata n.
sp., Cedusa wolcotti (Muir), Cedusa sp.,
Agalliopsis tropicalis (?), and several species of
the genus Empoasca.

Dabek and H. Waters, ODM Coconut Lethal
Yellowing Team, Jamaica.
Further attempts to transmit the mycoplasma
associated with the lethal yellowing (LY) disease,
using field-collected, palm-feeding fulgorids, are

reported. Common species (such as Myndus (=
Haplaxius) crudus and Omolicna cubana), and
rarer species (such as Nymphocixea caribbea
and Otiocerus?sp.) of fulgorids were collected
directly from palm foliage at several sites in
eastern Jamaica where LY was active. Large
proportions of these fulgorids were collected
directly from diseased palms. Almost one-third of
the total of over 30,000 collected fulgorids were
screened for mycoplasma transmission by
allowing them to feed on periwinkle (Catharan-
thus roseus) before survivors were transferred
to coconut test palms. Samples of periwinkle
tissue which had received the fulgorids were
checked for mycoplasmalike bodies by electron

IN JAMAICA, 1977-79. A. J. Dabek and H.
Waters, ODM Coconut Lethal Yellowing Team,
Genera/species of the Cicadelloidea, collected
from the undergrowth of areas heavily infected
with lethal yellowing (LY), were screened for
natural transmission of plant mycoplasmalike
organisms (MLO) using periwinkle (Catharanthus
roseus) as an indicator plant. Two species,
Deltocephalus flavicosta and Ollarianus ball
(Euscelinea), transmitted MLO, as confirmed by
electron microscopy. On the basis of symptoms
produced on the periwinkle test plants, each
species transmitted a different type of MLO.
Ollarianus balli also transmitted MLO to
Cajanus cajan and to Rhynchosia minima, its
natural field host in Jamaica. Particular attention
was directed at these two insect species as
possible vectors of LY. Transmission tests to
coconut palms with the other members of the
Cicadelloidea were also conducted.

DUZEE. F. W. Howard, University of Florida, USA.
On the basis of its distribution, feeding habits
and host range, the planthopper Myndus (=
Haplaxius) crudus is suspected to be a vector

of lethal yellowing (LY) and the apparently iden-
tical lethal declines of 25 additional palm species.
The lethal palm declines, like LY, are associated
with mycoplasmalike organisms (MLO). To test the
hypothesis that M. crudus is a vector of these
diseases, an average of 18,565 planthoppers
were transferred from palms in LY-infected areas
to each of five cages containing healthy coconut
palms, Cocos nucifera L., and Manila palms,
Veitchia merrillii (Becc.) H. E. Moore. Palms in
five similar cages did not receive M. crudus in-
troductions. Manila palms in four of the five cages
with M. crudus contracted lethal decline. Elec-
tron microscopy confirmed the presence of MLO.
This experiment is still in progress.

OF X DISEASE AGENT. A. H. Purcell, J. Richard-
son and A. Finlay, University of California, USA.
The leafhopper Macrosteles fascifrons StSl
failed to transmit the X disease (XD) agent (peach
yellow leafroll strain) to celery after acquisition
feeding on diseased celery or following needle in-
jections of extracts of the XD agent. The relative
titer of the XD agent in previously injected M.
fascifrons was assessed at intervals over a
period of 35 days. The assay was done by in-
jecting noninfective Colladonus montanus (Van
Duzee), which then were evaluated individually for
transmission of XD agent to celery. Infectivity of
extracts prepared from M. fascifrons was not
detected before 25 or 37 days after the donor M.
fascifrons had been injected. Serial passage of
the XD agent via needle injection was demon-
strated in M. fascifrons for 3 passages. Further
passages resulted in the rapid death of recipient
leafhoppers. Electron microscopy of injected M.
fascifrons revealed mycoplasmalike organisms
surrounding the salivary glands, but not within the
salivary glands. Results indicate that the XD agent
can multiply in M. fascifrons, which is not a vec-
tor of this agent, possibly because of a salivary
barrier to the passage of the XD agent.

YELLOWING VECTOR(S). J. H. Tsai, University
of Florida, USA.
Myndus (= Haplaxius) crudus, Idioderma
virescens, Macrosteles fascifrons, Dalbulus
maidis, Spangbergiella vulnerata, Peregrinus
maidis, and Graminella spp were tested as vec-
tors of lethal yellowing (LY) on a variety of LY
susceptible palms in the last two years. A total of
51,422 M. crudus adults were given 1-3 day
acquisition access periods (AAP) on diseased
palms. At the end of AAP, 23,712 survivors were
transferred to 13 test palms. Another 53,305 M.
crudus adults were collected from LY areas and

directly released into four rooms containing 26
potted palms. A group of 573 M. crudus were in-
jected with crude sap and lyophilized meristem
tissue from infected palms and tested on three
potted palms. Of the total 6,680 M. fascifrons
given 5-9 day AAP, 3,212 insects were trans-
ferred either first to an intermediate host or direct-
ly to six potted palms. For alternate host tests, a
group of 2,544 M. crudus recovered after a 2-
day AAP on diseased palms were tested on four
periwinkle plants. Another group of 9,325 M.
crudus were tested on five periwinkle plants
without AAP.'1,551 M. fascifrons were injected
with phloem sap and lyophilized meristem tissue
from infected palms and tested on three potted
palms. Other transmission tests included 5,480 D.
maidis, 700 S. vulnerata, 1,500 P. maidis, and
1,510 Graminella spp on 13 potted palms. Thir-
ty-two /. virescens were collected from a LY area
and caged on a potted palm. So far eight test
palms have shown disease symptoms but
mycoplasmalike organisms were observed in only
two Pritchardia palms that were used in tests
with M. crudus. Because these two palms were
not continuously caged, more tests are in
progress. Investigation of eriophyid mites
associated with LY palms yielded no positive
R. Townsend, John Innes Institute, UK.
Three-week old plants of Nicotiana rustica
were injected in the midvein of the fifth or sixth
leaf wth turbid suspensions of Spiroplasma citri
or corn stunt spiroplasma in phosphate buffered
saline with 5% sucrose (PBS/sucrose). After 20
days at 21 C, plants exhibited severe stunting
resulting from the shortening of internodes.
Proliferation of lateral shoots was apparent.
Leaves were greatly reduced in size, thickened
and distorted, but not yellowed. Flowers, if form-
ed, were extremely small and discolored and
failed to produce seeds. Electron microscopy
revealed abnormal development of the vascular
tissues but no evidence of spiroplasma infection.
Spiroplasmas could not be cultured from these
plants nor their presence detected by enzyme
linked immunosorbent assay. Control plants in-
jected with PBS/sucrose only, subsequently
developed similar symptoms. Less severe growth
abnormalities were also apparent in plants injected
with S. citri in 5% sucrose or PBS alone. Symp-
toms were also produced in other plant species in-
cluding Datura stramonium and Lycopersicum
esculentum following injections of spiroplasmas
suspended in PBS/sucrose or PBS/sucrose
alone. Experiments to elucidate the particular
agent or conditions responsible for producing
these effects are in progress.

VAN DUZEE IN FLORIDA. F. W. Howard, Univer-
sity of Florida, USA.
In Florida, hundreds of thousands of coconut
palms have been destroyed by lethal yellowing
(LY) on the Florida Keys and on the lower east
coast of the mainland. To the north of the
generally infected area, and on the Florida west
coast, there are extensive coconut plantings in
which less than 10 LY cases have been reported.

To test the hypothesis that the population density
of the suspected LY vector, Myndus (=Hap-
laxius) crudus, is higher in heavily infected
areas than in relatively disease-free areas, com-
parative sampling was conducted during 1978
and 1979. The average number of M. crudus
was 37 times higher in samples from the LY-
infected areas than in samples from the relatively
disease-free areas. This information supports the
hypothesis that M. crudus is the vector of LY.

Moderator: F. W. Howard

Howard, University of Florida, USA.
An experiment was conducted in Hollywood,
Florida, in an area affected by lethal yellowing (LY)
and the lethal palm declines which are also
associated with mycoplasmalike organisms.
Manila palms, Veitchia merrillii (Becc.) H. E.
Moore, were given foliar applications of in-
secticides (diazinon AG 500 at 13 ml / 10 I, or
dimethoate 400 at 26.4 ml/10 I) biweekly for 15
months. Myndus (=Haplaxius) crudus Van
Duzee was the most abundant auchenorrhyn-
chous insect sampled from the leaves of Manila
palms. There were fewer M. crudus in samples
from palms treated with diazinon than in samples
from untreated palms (P<0.05). The rate of
spread of the disease declined significantly in the
diazinon and dimethoate-treated plots, but not in
the untreated plots (P< 0.05). The results suggest
that a leaf-feeding insect, possibly M. crudus, is
the vector of LY.

Chiarappa, FAO of the United Nations, Italy.
The origin of lethal yellowing is considered in
light of newly acquired information on endemicity,
geographic distribution of resistance genes, com-
parative morphology, physiology, symptomatology
and susceptibility of various coconut germplasm
introductions. The origin of certain groups of
varieties is traced back to geographical areas
where wilt diseases are endemic. An analysis of
the occurrence and behavior of wilt diseases and
of their response to oxytetracycline suggests a
single etiological agent causing various forms of
disease expression under different pathosystem
conditions. The implications of this new in-
formation are reviewed and the need of certain
research priorities are discussed.

IN MALAYSIA? K. Maramorosch, Rutgers Univer-

sity, USA.
Malaysian Wilt of coconut palms (bud rot) has
been described from the Bernam River district
(Sharp, 1928), Johore (Johnston, 1957) and
Sarawak, North Borneo (Maramorosch, 1964).
Flowering spikes of affected palms became
discolored with necrotic patches resembling
lethal yellowing (LY)-affected inflorescences.
Leaves turned yellow, bud tissues became
necrotic and evil smelling, nuts dropped
prematurely and palms died within 5 to 6 months.
Salmon-pink discoloration of stem tissues was ob-
served not only in diseased, but also in apparently
healthy trees in affected areas. In the past the
disease has been of no economic importance
because of its slow and limited spread. Recently
Malaysian Wilt has caused severe losses in newly
introduced hybrids but not in native palms. This
has revived the hypothesis that the disease might
have originated in Malaysia where native palms
became resistant to the disease agent
(Maramorosch, 1964). If a mycoplasma etiology of
Malaysian Wilt were confirmed, this hypothesis
could explain the origin of the LY disease as well
as the origin of Malayan Dwarf palm resistance. A
search for additional resistant breeding material in
Malaysia would therefore seem warranted.
H. Romney, Coconut Industry Board, Jamaica.
Of 1,096 Malayan Dwarfs planted between
1962 and 1967 in resistance trials in areas of
lethal yellowing (LY), 60 or 5.5% were lost to LY
by 1973. Losses to LY in all varieties were almost
complete by 1973. Selection of mother-palms and
roguing in the nursery commenced during the mid-
1960s. Thirteen agronomy experiments planted
with this improved planting material between
1966 and 1974, comprising a total of 2,876
Malayan Dwarfs, were exposed to LY for three to
11 years, and only nine palms (0.31%) died from
LY compared with 1.3% lost to bud rot and 2.3%
to other causes. It is presumed that the resistance
of the Malayan Dwarf population to LY in Jamaica
improved further as susceptible members died

and ceased contributing to seed. In a survey of
farmers' fields conducted between 1971 and
1979, 124 plots with 25 Malayan Dwarf palms
each were exposed to LY for three to eight
years. Only six palms (0.2%) died from LY com-
pared with 2.8% lost to bud rot and 1.8% to other
causes. Malayan Dwarf seed exported from
Jamaica comes from the same seed sources as
seed used in Jamaica. There are currently 4.58
million Malayan Dwarf palms in Jamaica.

Been, Coconut Industry Board, POB 204,
Kingston 10, Jamaica. Twenty-eight local and in-
troduced varieties were planted in resistance trials
throughout the main coconut growing areas of
eastern Jamaica soon after lethal yellowing start-
ed to spread in that region. Sixteen years later the
disease is still active at only one trial site. Ceylon,
Indian and Malayan Dwarfs, and King coconuts ap-
pear to be highly resistant; while Bougainville,
Cambodia, Malayan, Markham Valley, Panama,
Peru, Rotuma, Sarawak, Thailand and Yap Tails,
and Fiji Dwarfs seem to be less resistant. Highly
susceptible varieties are Indian, Jamaica and New
Hebrides Tails and Rangiroa Dwarfs; while the
less susceptible group comprises Ceylon, Fiji,
Rangiroa, Ranell, Samoa, Seychelles, Solomon,
Tahiti and Tonga Tails. In the absence of any

reliable inoculation technique, assessment of
resistance was based on natural infection which
occurred in the field.

University of Florida, USA. The resistance of palm
species to lethal yellowing (LY) is being deter-
mined by two methods. The first is by observation
of existing plants in diseased areas of Florida. Fair-
child Tropical Garden and the USDA Plant In-
troduction Station (Chapman Field), both in Coral
Gables, Florida, have a high diversity of palm
species that have undergone a great deal of
selective pressure by LY. Most species that are
highly susceptible to LY have been eliminated and
an estimate of LY resistance can be made for
those palms which remain. The second method of
evaulation is through the use of a one hectare trial
planting garden of over 200 palm species at the
Agricultural Research Center in Fort Lauderdale.
Research is underway to determine germination
methods, cultural requirements, and rate of
growth of these palms. Until a method of artificially
transmitting LY is developed, resistance will be
determined through exposure in LY infected
areas. Highly susceptible palms have been in-
terplanted with the test plants to increase the in-
cidence of LY in the trial.

Moderator: D. H. Romney

UK/LPTI Sub-Station, Indonesia.
A coconut disease of unknown etiology has
recently destroyed 13,000 local Tall trees on the
remote Indonesian island of Natuna (South China
Sea), and approximately 1,000 trees on Pulau Bin-
tan (near Singapore). The symptoms of sudden
nutfall, blackening of open and unopened in-
florescences, young spathe discoloration with
gummosis, spear leaf necrosis and rapid death
resemble, but are not identical with, those of lethal
yellowing. The upward progression of leaf
browning, often associated with rachis breaking,
resembles the condition associated with the
flagellated protozoan Phytomonas. A similar
(identical?) disease has started attacking coconut
palms on the Sumatran mainland near Pekan Baru.
Microorganisms were not seen by light micro-
scopy in samples of affected tissues from
these palms.

V. Feather, H. D. Ohr and D. E. Munnecke, Univer-
sity of California, U.S.A.
Recently, a serious disease has caused the
decline of many Canary Island date palms,
Phoenix canariensis, which are grown ex-
tensively as ornamentals in southern California.
The disease is characterized by reduction of tree
canopy, unilateral death of leaves, discoloration of
vessels and a general punky rot of affected leaf
and bud tissues. Two fungi, Fusarium
oxysporum and Gliocladium vermoeseni,
have been consistently cultured from leaves of
diseased trees located on the west side of the
coastal mountain range in Los Angeles, Orange,
San Diego, and San Bernardino counties. Both
fungi are pathogenic singly and in combination on
seedlings of P. canariensis and the true date
palm, P. dactylifera. Symptoms of the disease

are similar to those reported on P. canariensis in-
fected with F. oxysporum in France, Italy, and
Japan. Pure cultures of F. oxysporum have been
isolated from field-grown P. canariensis nursery
trees in the low desert on the east side of the
coastal mountain range in San Diego county. G.
vermoeseni was not isolated from these trees.
The occurrence of the disease in the low desert is
evidence that F. oxysporum is able to survive
and cause disease in hot, dry environments.

AMERICA. M. Dollet, IRHO/GERDAT, France.
On the west coast of Ecuador, between Santo
Domingo and the Pacific Ocean, coconuts suffer
from wilts generally suspected to be red ring
disease. However, our investigations show that in
about 80% of the cases, flagellated protozoa are
involved. In a survey of weeds near the affected
oil palm or coconut plantations in Ecuador, five dif-
ferent species of Euphorbia and one Asclepias
were found that harbored flagellates. Two species
of infected euphorbias, Euphorbia prostrata Ait.
(?) and Euphorbia foliolosa Boiss. (?) showed
disease symptoms. Euphorbia foliolosa is often
seen adjacent to palms in plantations. The other
species manifested no symptoms. Euphorbia
hirtella Boiss. (?) had a 90% infection rate in cer-
tain coconut plantations. Asclepias curassavica
L. is also a host to flagellates, but without symp-
toms. Chemotherapeutic trials have been made in
vitro and by injection in the diseased palms with
different products supplied by Rhone-Poulenc,
Vitry, France pentamidinee dichlorhydrate,
isometamidium chloride, stilbamidine isethionate)
and with Endrin, the insecticide used preventively
against marchitez in oil palms.

Landbouwprofstation, Surinam.
The symptoms of hartrot or fatal wilt of coconut
palms in Surinam are similar to those of lethal
yellowing. Flagellated protozoa are found in the
phloem of the diseased palms. In an attempt to
bring the incidence of the disease under control
by eliminating the possible vector(s), insecticides
such as Endrin and Sevin were applied
periodically to the base of the coconut palms, a
treatment that has given favorable results in oil
palms affected by flagellated protozoa in Surinam
and Colombia. However, preliminary results after
20 months of trials, indicate that none of the in-
secticides applied gave control of the disease in
coconut palms.

ROT OF COCONUTS. V. T. Alexander, Land-
bouwprofstation, Surinam.
The Malayan Dwarf coconut palm is susceptible
to hartrot or fatal wilt, based on trials conducted in
Surinam. Comparative variety trials for resistance
to hartrot indicated that Surinam Dwarf is the most
susceptible followed by Ceylonese Dwarf and
Malayan Dwarf. Maximum resistance is found in
Surinam Tall. The resistance of Surinam Tall may
have been due to selection of seedlings from
mother plants that had survived in an area that had
been infected for many years.

Martinez-Lopez, O. Jimenez and E. Mena-Tascon,
Institute Colombiano Agropecuario, Colombia.
Coconut palm, one of the most important crops
on the Pacific Coast of southwest Colombia, has
been seriously affected by the red ring disease.
As one of the control measures for the disease,
the Instituto Colombiano Agropecuario has been
testing and recommending the planting of cultivars
with resistance to red ring disease. This control
program is impaired by the outbreak of a new
disease in these cultivars. The symptoms of the
disease are characterized by brown discoloration
and wilting of the leaves, necrosis of in-
florescences and the spear leaf, brown
discoloration in the meristem, root rot, and death
of diseased palms. Observations of the diseased
palms indicated the presence of flagellated
protozoa that resembled the Phytomonas
protozoa found in association with hartrot disease
of coconut palm in Central and South America and
in one type of marchitez sorpresiva of African oil
palm, found in several countries in South America.
As in the other reports of Phytomonas in palms,
the pathogenicity of the flagellates has not been
determined and their mode of spread has not
been identified. The disease has not been a
problem in African oil palms grown in the area, but
further and more careful observations are
necessary. Myndus (= Haplaxius) sp, the vector
of a wilt disease of oil palms which is not
associated with protozoa, has not been observed
in this area.

IN COLOMBIA. R. E. McCoy, University of
Florida, USA; and G. Martinez-Lopez, Instituto
Colombiano Agropecuario, Colombia.
The "Case-9" disease of African oil palm occurs
near Puerto Wilches on the Magdelena River in
central Colombia. Young leaf base samples collect-
ed from diseased palms contained numerous

uniflagellated protozoa within the sieve elements
of the phloem. These appeared typical of the
Phytomonas seen in sudden wilt-diseased oil
palms and hartrot-diseased coconut palms.
"Case-9" is similar to sudden wilt in that the
primary response is a rapid collapse and "burn-
ing" of the foliage. However, significant dif-
ferences exist in the symptomatology and
epidemiology of these diseases and we have
followed the suggestion of O. Jiminez and A.
Reyes in differentiating "Case-9" from sudden

BLIGHT. J. K. Dunaway and D. G. Mead, Little
Green Acres Nursery, USA.
During this study Pseudomonas aeruginosa
was isolated repeatedly from diseased tissue. The
lethal palm blight in Florida appears to be initiated
by numerous factors, many of which must occur in
sequence to cause death of the tree. Preliminary
results indicate that adequate control of this
disease syndrome in palms is possible by the ap-
plication of chemicals.

sity of Florida, USA.
In 1978 Dunaway and Mead (Proc. Fl. St. Hortic.
Soc. 91:243) reported that the disease "lethal
palm blight" was affecting 50 species of palms in
south Florida, including the coconut cultivars
Jamaica Tall and Malayan Dwarf. It was inferred
that this disease was lethal yellowing. They
claimed the disease affected not only palms, but
avocados, snapbeans, and bananas as well. The
environmentally ubiquitous bacterium
Pseudomonas aeruginosa was isolated from
these sources and reported to be pathogenic to
palms. An isolate supplied by Dunaway and Mead
was verified as P. aeruginosa, clinical strain E-2
by M. N. Schroth of the University of California.
Twenty-four 3-year-old Malayan Dwarf and seven
35-foot Jamaica Tall coconut palms were
inoculated with suspensions of 70-100 million P.
aeruginosa cells per ml of phosphate buffered
saline. Inoculations were effected in the Malayan
Dwarfs by petiole injection (12 trees) and by
surgically exposing the tender spear leaf base and
injecting 8 ml of inoculum into the bud (12 trees).
The mature Jamaica Tails were inoculated by
drilling a 6 inch deep hole in the soft trunk tissue
just below the crown shaft and filling this with the
bacterial suspension. In addition, coconut in-
florescence tissue grown in tissue culture medium
was inoculated with P. aeruginosa. In no case
was any tissue damage attributable to P.
aeruginosa. After 2 months, P. aeruginosa was
isolated from all inoculated coconut tissues at-

tempted. After 4 months, no pathogenic effects
were visible at the inoculation sites or elsewhere
in the trees. In coconut tissue culture, P.
aeruginosa grew on the medium surrounding the
tissues and was readily re-isolated after several
weeks, yet no tissue damage was evident. It must
be concluded from these tests that the Dunaway
and Mead strain of P. aeruginosa, even under
severe inoculum pressure, has no pathogenicity
to coconut palm.

dies, J. S. Imperial, P. Palukaitis, T. Hatta and G.
Boccardo, The University of Adelaide, Department
of Plant Pathology, Glen Osmond, South Australia
Two RNA species (ccRNA, and ccRNA2) were
uniquely associated with the cadang-cadang
disease of coconut. Comparative studies showed
that nuclease digestion and thermal denaturation
kinetics of ccRNA, are similar to those of other
viroids. In denaturing formamide polyacrylamide
gels, the molecular weight of ccRNA1 was
estimated to be 63-73,000. When observed elec-
tron microscopically, ccRNA, appeared as cir-
cular single-stranded molecules comprising 310
3 nucleotides with an estimated molecular
weight of 105,000. Transmission of the two ccR-
NAs to young coconut seedlings was achieved
using total nucleic acid extracts from diseased
coconuts as inoculum. Fractionation by sucrose
density gradient centrifugation showed that in-
fectivity is associated with the fraction containing
ccRNAs only. Tritium-labelled DNA complementary
to ccRNA, (cDNA), was synthesized using S,-
nuclease cleaved polyadenylated ccRNA, as the
template for avian myeloblastosis virus reverse
transcriptase. A Rot/2 value 1 x 103 mol.s/I was
obtained in homologous hybridization ex-
periments, consistent with a unique RNA species
of approximate molecular weight 100,000. The
cDNA has been used as a probe for the detection
of ccRNA, in crude nucleic acid extracts from
diseased coconuts. The cDNA also allowed
detection of nucleotide sequences identical to
ccRNA, in oil and buri palms displaying cadang-
cadang-like symptoms.

RESEARCH. A. E. Bigornia, E. P. Pacumbaba, E.
P. Rillo and J. S. Imperial, Philippine Coconut
Authority, Philippines.
Although the cadang-cadang disease is restrict-
ed to the Philippines, it remains one of the most
destructive and complex maladies of the coconut
palm today. Recent epidemiological data con-
firmed the very slow spread of the disease, with a
rate of outward spread of less than 500 meters

per year within infected plots. Disease incidence
significantly declined over the last ten years in two
provinces. While the disease has a slow rate of
spread within infected plots, new sites of in-
fection from 50 to 100 km away from old in-
fections have been recorded. Insect and eriophyid
mite transmission trials have so far been un-
successful. The main insect groups under study
are Homoptera, Coleoptera, and Orthoptera.
Phytophagous mites, both vagrant and colonizing
on coconut palms, have also been used in tests.
Biochemical and mechanical transmission studies
point to a viroid nature of the pathogen. Two low
molecular weight ribonucleic acid (RNA) species,
with properties similar to known viroids, are
associated with the disease and recently were
shown to be infectious. Other studies being pur-
sued on the cadang-cadang RNAs include struc-
ture and molecular variation, optimum conditions
for mechanical transmission, screening for
resistance, host range, and relationships with
possible insect vectors.

IN ECUADOR. C. Garzo'n Flor and E. MoraCarrillo,
INIAP, Ecuador.
Research was conducted at the Experimental
Station of Santo Domingo, Ecuador, to determine
the causal agent of the bunch rot disease of oil
palms, and to determine the influence that artificial
pollination has on the incidence of the disease.
Colletotrichum sp, Fusarium sp, Rhizoctonia
solani, Botryodiplodia theobromae and an un-
determined bacterium were isolated from rotting
tissues. Fusarium sp was isolated most frequent-
ly. The disease was not induced by any of the
fungi or bacteria when they were used in
pathogenicity tests. The disease incidence was
greatest in artificially pollinated female in-
florescences when low quantity of pollen was
used. In order to reduce the incidence of bunch
rot, it is advisable to harvest every week as well as
to clean the plants twice or three times a year.

M. Figueroa N., INIAP, Ecuador.
The causal agent of the spear rot of oil palms,
Elaeis guineensis, occurring in the Santo

Domingo area, Ecuador, was investigated. Both
Fusarium roseum and Fusarium oxysporum
were isolated from diseased tissues but F.
roseum was found more frequently. Each of
these species reproduced the typical disease
symptoms on 30-day old seedlings inoculated un-
der green house conditions, but only after wound-
ing the inoculation site. Several fungicides, at
concentrations of 100 to 500 ppm of active
ingredient were added to the culture medium on
which both Fusarium spp were grown in vitro.
The systemic fungicides Bavistin, Benlate,
Derosal, Mertec, Saprol, and Vitavax-Thiram, even
at the lowest rate used, inhibited the mycelial
growth of F. roseum completely. The same
fungicides, except for Saprol and Vitavax-Thiram,
also inhibited F. oxysporum. Both Fusarium spp
were also inhibited by foliar protectant fungicides
like Samazin, Celaneb and Trimangol at all the con-
centrations tested. Some inhibition was produced
by Poliram M on F. roseum, and by Dikar on F.
oxysporum, but only at the highest rates used.

In 1959 Robertson attributed oil palm blast to a
mixed fungus infection. Blast was discovered on
coconut in the Ivory Coast in 1971. Early studies
indicated the role of an insect vector and further
experimentation demonstrated that Ricelia mica
(Homoptera, Cicadellidae) transmits blast to oil
palm and coconut. Trials of mechanical trans-
mission were undertaken in 1974, but without
positive results. The first electron microscopic
examinations showed rickettsialike organisms
(RLO) in the xylem of diseased palms. Trials of
blast transmission to herbaceous plants by
Recilia were carried out. Symptoms of wilting, in-
cluding progressive dwarfing of the flowers,
crinkling and yellowing of the leaves, followed by
the total disappearance of flowers and the
cessation of growth, were obtained on Catharan-
thus roseus. Electron microscopic examination
of these periwinkles revealed mycoplasmalike
organisms (MLO) in phloem tissues. The salivary
glands of Recilia are now being examined. The
role of the RLO and MLO found in the oil palm and
in periwinkle is discussed. Treatments with
tetracycline suggest a mycoplasma etiology.


*ALEXANDER, V. T. Landbouwprofstation,
POB 160, Paramaribo, Surinam, S.A.
*ARCHER, D. B. John Innes Institute, Colney
Lane, Norwich NR4 7UH, United Kingdom.
BARRANT, C. I. Coconut Industry Board,
POB 204, Kingston 10, Jamaica, W.I.
*BIGORNIA, A. E. Philippine Coconut Authority,
Diliman, Quezon City, Philippines.
*BOCCARDO, G. Laboratorio di Fitovirologia
Applicata del CNR, Via O. Vigliani 104,10122
Torino, Italy.
*CHIARAPPA, L. FAO of the United Nations, Via
delle Terme di Caracalla, 00100-Rome, Italy.
*DABEK, A. J. ODM Coconut Lethal Yellowing
Team/Coconut Industry Board, POB 204,
Kingston 10, Jamaica, W.I.
DELGADO DE GARAY, A. Impulsora Guerre-
rense del Coccotero, Londres 40, Mexico 6, D.F.
34032 Montpellier-Cedex, France.
*EDEN-GREEN, S. J. ODM Coconut Lethal
Yellowing Team/Coconut Industry Board,
POB 204, Kingston 10, Jamaica, W.I.
Ecuador, S.A.
GOODISON, A. Coconut Industry Board, 6100
Leonardo Street, Coral Gables, FL 33146, U.S.A.
GRIFFITH, R. Red Ring Research Division,
Centeno, Arima, Trinidad, W.I.
*HUNT, P. ODM,UK/LPTI Sub-Station, Solok,
Sumatera Barat, Indonesia.
*MARKHAM, P. G. John Innes Institute, Colney
Lane, Norwich NR4 7UH, United Kingdom.
*MARTINEZ-LOPEZ, G. Instituto Colombiano
Agropecuario, A.A. 151123, Bogota, Colombia, S.A.
OLLAGNIER, M. IRHO, 11 Square Petrarque,
75016 Paris, France
*Indicates formal participation in meeting

REUVENI, O. A.R.O. Volcani Center, POB 12,
Bet-Dagan, Israel.
*ROMNEY, D. H. Coconut Industry Board, POB
204, Kingston 10, Jamaica, W.I.
SALAS, J. A. Compania Bananera de Costa
Rica, Golfito, Costa Rica, C.A.
SCHUILING, M. Deutsche GTZ, Postfach 5180,
D-6236 Eschborn 1, Federal Republic of Ger-
*TOWNSEND, R. John Innes Institute, Colney
Lane, Norwich NR4 7UH, United Kingdom.
TRIHARSO Faculty of Agriculture, Gadjah Mada
University, Jogjakarta, Indonesia.
VAN SLOBBE, W. G. L. M. Victoria, POB 1858,
Paramaribo, Surinam, S.A.

ALFIERI, S. A., JR. Division of Plant Industry,
POB 1269, Gainesville, FL 32602.
BAILEY, R. Division of Forestry, 909 SE 1
Avenue, Miami, FL 33131.
*BASHAM, H. G. ARC, IFAS, University of
Florida, 3205 SW 70 Avenue, Fort Lauderdale, FL
BRLANSKY, R. H. AREC, IFAS, University of
Florida, POB 1088, Lake Alfred, FL 33850.
CALLOWAY, P. Extension Division, IFAS,
University of Florida, Gainesville, FL 32611.
CARPENTER, J. B. USDA, US Date and Citrus
Station, Indio, CA 92201.
CARPENTER, W. J. Ornamental Horticulture
Department, IFAS, University of Florida,
Gainesville, FL 32611.
*CHEN, T. A. Plant Pathology Department,
Rutgers University, New Brunswick, NJ 08903.
DAIGLE, L. T. Dade County Extension, IFAS,
7370 NW 36 Street, Miami, FL 33166.
*DAVIS, R. E. Plant Virology Lab, ARS, USDA,
BARC-West, Beltsville, MD 20705.

*DONSELMAN, H. M. ARC, IFAS, University of
Florida, 3205 SW 70 Avenue, Fort Lauderdale, FL
*DOWELL, R. V. ARC, IFAS, University of
Florida, 3205 SW 70 Avenue, Fort Lauderdale, FL
DRUMMOND, P. International Palm Society,
9540 Old Cutler Road, Miami, FL 33156.
*DUNAWAY, J. K. Little Green Acres, 10510
SW 108 Terrace, Miami, FL 33176.
ECKERSLEY, W. T. Tedco Inc., 2550 Ray
Court, Lantana, FL 33462.

*ENNIS, W. B., JR. ARC, IFAS, University of
Florida, 3205 SW 70 Avenue, Fort Lauderdale, FL
*ESKAFI, F. M. ARC, IFAS, University of Florida,
3205 SW 70 Avenue, Fort Lauderdale, FL 33314.
*FEATHER, T. V. Plant Pathology Department,
University of California, Riverside, CA 92521.
FRENCH, W. J. ARC, IFAS, University of Florida,
Route 3, Box 213 B, Monticello, FL 32344.
GAMMEL, W. A. Modern Seedlings, Box 570-
178, Perrine, FL 33157.

GRIFFIS, J. L. Ornamental Horticulture Depart-
ment, IFAS, University of Florida, Gainesville, FL
GWIN, G. H. Division of Plant Industry, 13603
Old Cutler Road, Miami, FL 33158.
HADLEY, F. West Palm Beach Parks Depart-
ment, POB 3366, West Palm Beach, FL 32301.
HODYSS, L. B. Palm Beach County Extension,
IFAS, 531 North Military Trail, West Palm Beach,
FL 33406.
*HOWARD, F. W. ARC, IFAS, University of
Florida, 3205 SW 70 Avenue, Fort Lauderdale, FL

HULL, D. L. Dade County Extension, IFAS,
18710 SW 288 Street, Homestead, FL 33030.
LEE, R. L. AREC, IFAS, University of Florida,
POB 1088, Lake Alfred, FL 33850.
*MARAMOROSCH, K. Waksman Institute of
Microbiology, Rutgers University, Piscataway, NJ
MCCLINTOCK, M. Division of Forestry, 3315
SW 70 Avenue, Fort Lauderdale, FL 33314.

*MCCOY, R. E. ARC, IFAS, University of
Florida, 3205 SW 70 Avenue, Fort Lauderdale, FL
MCCOY, R. J. Procter & Gamble Company,
POB 599, Cincinnati, OH 45201.
MIDCAP, J. T. Ornamental Horticulture Depart-
ment, IFAS, University of Florida, Gainesville, FL
OGLESBY, R. Oglesby Nursery Inc., 3714 SW
52 Avenue, Hollywood, FL 33023.
*OHR, H. D. Plant Pathology Department,
University of California, Riverside, CA 92521.
O'MEARA, J. Division of Forestry, Collins
Building, Tallahassee, FL 32301.
PERRY, V. G. Office of Dean for Research,
IFAS, University of Florida, Gainesville, FL 32611.
PISACANO, S. Dade County Extension, IFAS,
7370 NW 36 Street, Miami, FL 33166.
*PURCELL, A. H. Entomology Department,
University of California, Berkeley, CA 94720.
PURDY, L. H. Plant Pathology Department,
IFAS, University of Florida, Gainesville, FL 32611.
*RAJU, B. C. Plant Pathology Department,
University of California, Davis, CA 95616.
ROOD, N. W. Rood Landscape Company, POB
1568, Jupiter, FL 33458.
RUGGIERO, J. C. Davis Gardens Inc., 6767 SW
67 Avenue, South Miami, FL 33143.
SCHLEGEL, J. W., JR. City of Fort Lauderdale,
POB 14250, Fort Lauderdale, FL 33302.
SCHUYT, A. M. Miami Parks Department, 2400
NW 14 Street, Miami, FL 33134.
SEYMOUR, C. P. Division of Plant Industry, POB
1269, Gainesville, FL 32602.
SLAYMAKER, W. R. Division of Forestry, 3315
SW 70 Avenue, Fort Lauderdale, FL 33314.
*SMITH, A. J. ARC, IFAS, University of Florida,
3205 SW 70 Avenue, Fort Lauderdale, FL 33314.
SMITH, C. M. E. I. DuPont de Nemours,
Wilmington, DE 19898.
*SOOWAL, J. M. East Marsh Nursery, Inc.,
1900 North Federal Highway, Dania, FL 33004.
TAMSBERG, J. B. Division of Forestry, 3315
SW 70 Avenue, Fort Lauderdale, FL 33314.
THEOBOLD, W. F. Division of Forestry, Collins
Building, Tallahassee, FL 32301.

*THOMAS, D. L. ARC, IFAS, University of
Florida, 3205 SW 70 Avenue, Fort Lauderdale, FL
THOMAS, R. E. Editorial Department, IFAS,
University of Florida, Gainesville, FL 32611.
*TISSERAT, B. H. USDA, US Date and Citrus
Station, Indio, CA 92201.
*TSAI, J. H. ARC, IFAS, University of Florida,
3205 SW 70 Avenue, Fort Lauderdale, FL 33314.
*TULLY, J. G. National Institute of Allergy and
Infectious Diseases, Building 7, Room 200, Be-
thesda, MD 20014.

WATSON, L. E. Broward County Extension,
IFAS, 3245 SW 70 Avenue, Fort Lauderdale, FL
WOODS, C. T., JR. Editorial Department, IFAS,
University of Florida, Gainesville, FL 32611.
ZERBA, R. H. Monroe County Extension, IFAS,
POB 2545, Key West, FL 33040.
*ZIMMERMANN, M. H. Harvard Forest, Peter-
sham, MA 01366.