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Group Title: Bulletin - University of Florida Agricultural Experiment Station ; no. 199
Title: Coconut bud rot in Florida
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027165/00001
 Material Information
Title: Coconut bud rot in Florida
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 87 p., 2 folded leaves : ill., charts ; 23 cm.
Language: English
Creator: Seal, J. L ( James Lewis ), b. 1893
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1928
 Subjects
Subject: Coconut palm -- Diseases and pests -- Florida   ( lcsh )
Phytophthora palmivora   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibiography: p. 84-87.
Statement of Responsibility: by James L. Seal.
General Note: Cover title.
General Note: Originally presented as: Thesis (Ph.D)--University of Minnesota.
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00027165
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000923506
oclc - 18173750
notis - AEN4057

Table of Contents
    Historic note
        Historic note
    Title Page
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    Credits
        Page 2
    Table of Contents
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    Main
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Full Text





HISTORIC NOTE


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

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






September, 1928


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
Wilmon Newell, Director










COCONUT BUD ROT IN FLORIDA


By JAMES L. SEAL






Technical Bulletin


















Bulletins will be sent free upon application to the
Agricultural Experiment Station
GAINESVILLE, FLORIDA


Bulletin 199







BOARD OF CONTROL


P. K. YONGE, Chairman, Pensacola
E. W. LANE, Jacksonville
A. H. BLENDING, Leesburg
W. B. DAVIS, Perry


E. L. WARTMANN, Citra
J. T. DIAMOND, Secretary, Talla-
hassee.
J. G. KELLUM, Auditor, Tallahassee


STATION EXECUTIVE STAFF
WILMON NEWELL, D. Sc., Director IDA KEELING CRESAP, Librarian
S. T. FLEMING, A. B., Asst. to Di- RUBY NEWHALL, Secretary
rector K. H. GRAHAM, Business Manager
J. FRANCIS COOPER, B. S. A., Editor RACHEL MCQUARRIE, Accountant
ERNEST G. MOORE, M. S., Asst. Ed

MAIN STATION-DEPARTMENTS AND INVESTIGATORS


AGRONOMY
W. E. STOKES, M. S. Agronomist
W. A. LEUKEL, Ph. D., Asso.
C. R. ENLOW, M. S. A., Asst.*
FRED H. HULL, M. S. A., Asst.
J. H. WALLACE, Asst.
ANIMAL HUSBANDRY
A. L. SHEALY, D.V.M., Veterinarian,
in Charge
D. A. SANDERS, D.V.M., Asst. Vet.
E. F. THOMAS, D. V. M.. Lab. Asst.
F. X. BRENNEIS, B. S. A., Asst.
Dairy Investigations
CHEMISTRY
R. W. RUPRECHT, Ph.D., Chemist
R. M. BARNETTE, Ph. D., Asst.
C. E. BELL, M. S., Asst.
H. L. MARSHALL, M. S., Asst.
J. M. COLEMAN, B. S., Asst.
J. B. HESTER, B. S., Asst.
COTTON INVESTIGATIONS
W. A. CARVER, Ph. D., Asst.
M. N. WALKER, Ph. D., Asst.
E. F. GROSSMAN, M. A., Asst.
RAYMOND CROWN, B.S.A., Field Asst.


ECONOMICS, AGRICULTURAL
C. V. NOBLE, Ph. D., Ag. Economist
BRUCE McKINLEY, B. S. A., Asst.
M. A. BROKER, M. S. A., Asst.
R. H. HOWARD, B.S.A., Field Asst.
ECONOMICS, HOME
OUIDA DAVIs ABBOTT, Ph. D.. Chief
L. W. GADDUM, Ph. D., Asst.
C. F. AHMANN, Ph. D., Asst.
ENTOMOLOGY
J. R. WATSON, A. M., Entomologist
A. N. TISSOT, M. S., Asst.
H. E. BRATLEY, M. S. A., Asst.
HORTICULTURE
A. F. CAMP, Ph. D., Horticulturist
M. R. ENSIGN, M. S., Asst.
HAROLD MOWRY, Asst.
G. H. BLACKMON, M. S. A., Pecan
Culturist
PLANT PATHOLOGY
G. F. WEBER, Ph. D., Asso.
K. W. LOUCKS, B. S., Asst.
ERDMAN WEST, B. S., Mycologist
A. H. EDDINS, M. S., Asst.


BRANCH STATION AND FIELD WORKERS
W. B. TISDALE, Ph. D., Plant Pathologist, in charge, Tobacco Experiment
Station (Quincy)
Ross F. WADKINS, M. S., Lab. Asst. in Plant Pathology (Quincy)
JESSE REEVES, Foreman, Tobacco Experiment Station (Quincy)
J. H. JEFFERIES, Superintendent, Citrus Experiment Station (Lake Alfred)
W. A. KUNTZ, A. M., Assistant Plant Pathologist (Lake Alfred)
J. FRANKLIN FUDGE, Ph. D., Assistant Chemist (Lake Alfred)
GEO. E. TEDDER, Foreman, Everglades Experiment Station (Belle Glade)
R. V. ALLISON, Ph. D., Soils Specialist (Belle Glade)
J. L. SEAL, Ph. D., Associate Plant Pathologist (Belle Glade)
L. O. GRATZ, Ph. D., Associate Plant Pathologist (Hastings)
A. N. BROOKS, Ph. D., Associate Plant Pathologist (Plant City)
A. S. RHOADS, Ph. D., Associate Plant Pathologist (Cocoa)
STACY O. HAWKINS, M. A., Field Assistant in Plant Pathology (Homestead)
D. G. A. KELBERT, Field Assistant in Plant Pathology (Bradenton)
R. E. NOLEN, M. S. A., Field Assistant in Plant Pathology (Monticello)
FRED W. WALKER, Assistant Entomologist (Monticello)

*In cooperation with U. S. Department of Agriculture.














CONTENTS
PAGE
INTRODUCTION ....... ..................... ... ...---.. ...------- 5
DISTRIBUTION AND ECONOMIC IMPORTANCE ---...... ---..-.... --- -. 5
SYMPTOMS ........... .. ------------......--........ ...... 8
CAUSE OF THE DISEASE ........... .....-.......--- .....------ .........----- ... ------....- 10
STUDIES ON THE IDENTITY OF THE CAUSAL ORGANISM.--......................---------- 13
Materials and Methods ............~.-.........------ .. .- 13
PHYSIOLOGY OF THE CAUSAL ORGANISM ..---.......-....---... ---.----... 16
Growth on Various Media .............. -------. .....----- 16
Reaction to Temperature ..........................----.-------- 17
Reaction to Light .----.-............................. --- 20
MORPHOLOGY OF THE CAUSAL ORGANISM ------ --------................ 21
Mycelium ......--.....-...-............---. ------------...---- 21
Conidiophores ...----........... ....-.---- ---------- 22
Conidia ..................... ..--........---..--------------.-- 24
Chlamydospores ...........................--- ... ....------------- 26
Oospores ...................--......... .........- 26
Spore Measurements .........................---------... -------.. 26
Effect of Different Culture Media on Spore Size---------.......... .... 41
Comparative Size of Spores of Different Strains on Same Media.... 50
Length to Width Ratio ......-- ...................------ ---- 60
PATHOGENICITY OF THE VARIOUS ORGANISMS .......................---- --- 67
LIFE HISTORY OF THE CAUSAL ORGANISM ..... --------.......... ...- 69
Source of Inoculum ...---........... ...---------------... 69
Dissemination of the Fungus -.......-..---....... --...... 70
Longevity of the Spores .............................. ---............. 71"
SPORE GERMINATION .....---.-----...-. --.-------.. -...--.....-.--........ -- 71
Conidia ....----......--------.. .....----. ------.... 71
Chlamydospores .....-.....-------.... ------...- ..--------- 75
METHOD OF INFECTION ............................- ............. 76:
PATHOLOGICAL ANATOMY ...........--.......--..------------------ 76
SEASONAL DEVELOPMENT OF THE DISEASE...--------- ---........------ 78
CONTROL .......---.........--....... -----........-....---------.-- 79
DISCUSSION --. ----.----...~....... .....------------.. ----- 80
SUMMARY ....-.......... ...... ....--- .-------- .----....----. 82
LITERATURE CITED ....-...... .----------------------- ...----. 84












',", *


N"


Fig. 1.-Coconut palms naturally infected with bud rot. In A, B, and C
the buds are entirely missing, while in D the bud may be seen hanging
from the top of the trunk.









COCONUT BUD ROT IN FLORIDA'
By JAMES L. SEAL2
INTRODUCTION
The most destructive disease of the coconut palm (Cocos nuci-
fera Linn.) is bud rot. This disease is co-extensive with the
palm, which, in general, may be found encircling the earth in
a belt 1,500 miles north and south of the equator. Bud rot has
been known for about a century, and the results of numerous
researches on the disease have been published. In these various
works, the authors do not agree upon a specific causal organism,
as they suspect several species of Phytophthora. The work re-
ported in this paper was undertaken with the view of establish-
ing the relationship of the various so-called species of Phytoph-
thora attacking the coconut palm.

DISTRIBUTION AND ECONOMIC IMPORTANCE
The coconut palm (Cocos nucifera Linn.) is found in all-tropi-
cal countries within a belt of about 1,500 miles north and south
of the equator. The origin of the coconut palm, according to
Cook (11)," seems to be Central America, as it is there that the
greatest number of genera and species of the COCACEAE are
found. Bud rot is practically co-extensive with its host and was
reported from Cayman Island as early as 1834. Since then the
disease has been reported from all the countries that grow the
palm. From Florida there have been fragmentary reports for
the past 30 years, but it was not until January, 1924, that a
definite causal organism was found associated with the disease.
At that time, Dr. G. F. Weber isolated an organism from a bud
rotted palm growing in the vicinity of Miami. He considered
the organism to be Phytophthora faberi, as described by Rein-
king (28). Since the above date the organism has been found
generally distributed over the southeastern third of the state;

'This work was done in Florida while the writer was employed by the
State Plant Board. The work was done under the supervision of Dr. O. F.
Burger, to whom the writer wishes to acknowledge his indebtedness for
encouragement and helpful criticism during the progress of the work. The
writer a'so wishes to express his indebtedness to Drs. E. C. Stakman and
M. N. Levine, for assistance in analyzing and presenting the material.
'A these's submitted to the Faculty of the Graduate School of The Uni-
versity of Minnesota by James Lewis Seal in partial fulfillment of the re-
quirements for the Degree of Doctor of Philosophy.
'Numbers in parentheses (italic) refer to "Literature Cited" in the
back of this bulletin.





Florida Agricultural Experiment Station


extending from south of Miami to Ft. Pierce, a total distance of
about 140 miles along the coast. The great centers of palm


7, ,


C


Fig. 2.-Coconut palms naturally infected by bud rot. A-Young palm
with the diseased bud hanging from the top of the trunk. B-Bearing
palm with the central column in process of falling from the tree. C-
Row of old coconut palms interplanted with young plants, with both
showing considerable bud rot. D--Young palms showing bud rot.






Bulletin 199, Coconut Bud Rot in Florida


growing are around Miami and Palm Beach and it is here that
the disease is most prevalent.
In Florida the coconut palm does not play the economic role
that it does in many other parts of the world, but it does have
considerable commercial value as an ornamental plant, as it is
used very extensively in plantings in the southeastern section
of the state, and, in 1925, had a commercial value of approxi-
mately $3,000,000. At present there are some 200,000 bearing
trees and 2,000,000 or more nursery plants and young trees in
the state. The plants are usually grown from the nuts by plac-
ing them in nursery formation, i. e. 2 to 3 feet apart in rows 3


Fig. 3.-Two three-year-old nursery trees showing bud rot in different
stages of development. A-Plant showing an early stage of the dis-
ease. B-Plant showing advanced stage of the disease.

to 5 feet wide. Under such conditions the plants are grown
crowded for a period of two to five years. As the plants grow
older they are usually thinned by removing every other plant.
These nurseries are generally located on low peat soil where
the plants make a very rapid growth, but nevertheless, they are
usually inundated by water one or more times each year. It is
in these nurseries that bud rot takes its greatest toll, but it is






Florida Agricultural Experiment Station


not limited to palms on low ground, as bud rot has been found
on many palms growing on high dry soil. Up to the present, some
75,000 diseased plants have been destroyed.

SYMPTOMS
The most noticeable symptom of bud rot is the dying and
dropping of the bud during the later stages of the disease. The
earlier stages of the disease may be recognized by one of three
distinct symptoms: first, a spotting of the unrolling leaves,


Fig. 4.-Two types of leaf injury often noted in inoculated plants. A-
Spotting of the pinnae. B-Bud of young plant showing spotting across
all the pinnae.







Bulletin 199, Coconut Bud Rot in Florida 9

which may either be confined to a few of the leaflets or extend
across all of a given leaf or, in some instances, several leaves;
second, a blotching or killing of a few or many of the leaflets
before they emerge from the sheath; and third, a sickly yellow-
ish appearance of the leaves, with or without spotting, as they
emerge from the sheath. In the first case the plant may recover
from the disease readily, as the fungus has not attacked the
primordal tissues; but in the second case the plant usually suc-
















1 1












Fig. 5.-Bases of leaves from a naturally infected palm. A-Four leaf
bases from a bud rotted palm arranged from right to left as they ap-
peared around the bud. B-Enlarged view of No. 3 in A, showing tufts
of mycelium on the tissues.

cumbs to the attack of the fungus, as every succeeding leaf is
usually infected and it is usually only a short time until the
fungus reaches the primordal tissues. In the third case the pri-







Florida Agricultural Experiment Station


mordal tissues are infected at the time the symptom is noted,
and it is only a matter of a few days until the bud dies. The
plant may remain alive for some time but it eventually dies
as the older leaves are killed. In case a tree is bearing at the
time it is attacked, the young nuts readily drop, while the older
ones remain until mature. In the first stages of the disease the
bud may easily be pulled from the plant, and the young meriste-
matic tissues are usually in a gelatinous mass that extends up
the petiole into tissues having a bluish or steel gray color, then
into a water soaked area, and finally into the white or creamy
yellow healthy tissues. In some cases there is a very distinct
brown line of demarcation between the diseased and the healthy
tissues. The firmer diseased tissues are frequently covered with
fungal hyphae, sometimes bearing chlamydospores but rarely
ever bearing conidia. The rotted tissues usually have a very
repulsive hog pen odor.'

CAUSE OF THE DISEASE
In 1907 Butler (6) reported that a parasitic Phytophthora
had been found in the bud of Palmyra palm (Borassus flabelli-
fer Linn.), Coconut palm (Cocos nucifera Linn.), and possibly
in the Areca palm (Areca catechu Linn.). He later concluded
(7) that this organism was a species of Pythium and called it
P. palmivorum Butler; but, still later, upon receiving a culture
of an organism isolated by Ashby from coconut palm in Jamaica,
he concluded that the correct name of the organism was Phy-
tophthora palmivora Butler (9). Coleman (10) in 1910 pub-
lished the results of his researches on the organism attacking
the Betel-nut palm and concluded that it was distinct from pre-
viously described organisms. He named it Phytophthora omni-
vora var. arecae n. sp. Shaw & Sundararaman (31), Sundarara-
man (35), and MacRae (23), all working in India, have con-
firmed Butler's work and agree that Phytophthora palmivora
Butler is the causative agent of bud rot in the various species
of palms in India. Johnston (17), from extensive researches on
coconut bud rot in Cuba, reported in 1912 that Bacillus coli
'The symptoms as reported for coconut bud rot in Florida are essen-
tially the same as those reported by Ashby (2) in Jamaica, Reinking (28)
in the Philippines, and Tucker (36) in Porto Rico. The outstanding dif-
ference between the symptoms as described elsewhere and those in Flor-
ida is the bluish or steel gray color of the diseased tissues which has been
noted frequently in specimens collected in the early stages of the disease
in Florida.







Bulletin 199, Coconut Bud Rot in Florida


(Ehrlich) Migula, or an organism practically identical with it,
was the causal pathogene. Working in Jamaica, Ashby (1), in
1915, described the coconut bud rot as reported by Johnston but,
in addition, found a Phytophthora-like organism associated with
the bacteria in producing the disease. In 1920 Ashby concluded
that two different species of Phytophthora were involved. He
stated that one, P. palmivora, caused a bud rot, and the second,
P. parasitica Dastur, caused a leaf stalk rot. He also stated that


Fig. 6.-Buds of nursery palms in the early stages of bud rot, showing felts
of mycelium on their basal parts. Lines of demarcation between the
diseased and healthy tissues shown.

the latter agrees closely with P. terrestris Sherbakoff (34) and
agrees with Dastur (12) that they are identical. Still more re-
cently, Ashby (3) concluded, from studies of Phytophthora caus-
ing cacao pod rot and coconut bud rot, that they were very sim-
ilar culturally and morphologically. However, as P. faberi Maubl.
would cause coconut bud rot only when the coconut plant was







Florida Agricultural Experiment Station


injured, and P. palmivora would not produce cacao pod rot, he
concluded that they are two distinct organisms.
P. faberi Maubl. produces the pod rot of the cacao plant, can-
ker in rubber trees, a rot of the papaw fruit, etc. in various
tropical regions. Von Faber (14) noted some minor differences
between this organism and P. omnivora as described by De-
Bary, but did not think the difference sufficiently great to justi-
fy establishing a new species. Nevertheless Maublanc (13) gave
this organism specific rank, apparently from Von Faber's find-
ings. Reinking (26) first decided that coconut bud rot in the
Philippines was caused by an organism very similar to Bacillus
coli but later concluded that Phytophthora faberi Maubl. caused
the disease and that the bacteria were secondary, or, at most,
only weakly parasitic. Reinking (28) later found, as a result of
physiological and morphological studies as well as from cross
inoculations, that P. faberi was the causal organism of coconut
bud rot as well as cacao pod rot. Sharples and Lambourne (30),
working in Malaya, isolated from palms that had been inundated
by water, three different bacteria which they used in inocula-
tion experiments along with P. faberi. All plants were inoc-
ulated by puncture. All of the organisms produced bud rot
symptoms in some of the plants. A high percentage of the checks
also died with bud rot, yet they drew the following conclusion:
"Nutritive bud-tissue of coconuts is a suitable pabulum for
any saprophytic organism, either bacterium or fungus; this
will develop and cause symptoms usually associated with bud
rot if inoculated directly into the bud tissues." Tucker (36), in
Porto Rico, found that bacteria would not cause bud rot in an
uninjured plant and concluded that the causal organism of
coconut bud rot is P. palmivora and that P. faberi is synony-
mous with it.
Recent work by Leonian (20) tends to show that the mor-
phology of the Phytophthoras is very variable and can not be de-
pended upon with any degree of accuracy for identification of
species, and that their physiology is just as variable. However,
he decided that many named species could be grouped into a
number of composite species. Leonian also concluded that there
are numerous saltations from various species of Phytophthora.
Gadd (15), working with several strains of P. faberi collected
from various hosts, found that these strains were very similar
in morphology and physiology but fell into two groups which he
considered to be biologic forms. In a more recent paper Gadd







Bulletin 199, Coconut Bud Rot in Florida


(16a) reviews the Phytophthoras associated with the bud rot
disease of palms and states that there are strong morphological
reasons for regarding P. faberi and P. palmivora as synonyms.
He concludes that it is inadvisable at present to drop either spe-
cies, as the oospore stage has not been found in pure culture,
although he does find that P. palmivora from coconut and
P. faberi from Odontadenia yield oospores in mixed cultures.

STUDIES ON THE IDENTITY OF THE CAUSAL ORGANISM
MATERIALS AND METHODS
Until a method was devised for isolating the causal organism
from bud rotted specimens, Phytophthora was very difficult to
recover, as the specimens were frequently overrun by bacteria
and fungi of various descriptions; of the latter, Fusariums,
yeasts, Diplodia and Thielaviopsis were the most common. The
first successful attempts at isolation were made by using one-
fourth inch cubes of the diseased material taken from the mar-
gin of the healthy and diseased tissues. These cubes were steril-
ized by soaking in mercury bichloride solution, 1-1000, for five
minutes, washed in sterile distilled water for a few minutes,
dipped in 70 percent alcohol, flamed, and then placed in dishes
of prune or corn meal agar. By using the above media the
growth of bacteria was retarded somewhat. It was still farther
retarded by placing the cultures in an ice box at approximately
18 C.
Later a more successful method was developed. The more bad-
ly decayed material was discarded, the outer portion of the dis-
eased bud was removed with a scalpel, and discs, one-fourth inch
in thickness, were cut from the remaining material and steril-
ized as described above. These sterile discs were then placed in
plates containing a small quantity of distilled water. The plates
were then placed in the ice box. In from 24 to 36 hours these
discs were covered with a white felty growth of Phytophthora,
in case this organism was present.
Specimens received at the laboratory were usually in vary-
ing stages of decay, but upon some of the more recently infected
material there was a white felt of mycelium which often yielded
pure cultures of Phytophthora when transferred directly to
agar plates. About 25 percent of the specimens collected from
600 or more properties yielded Phytophthora. However, many
of the collections were made from the same properties at dif-







Florida Agricultural Experiment Station


ferent dates. These various cultures of Phytophthora were com-
pared as to growth characters, spore production, and spore sizes
and then classified into groups. Without exception, they readily
fell into two classes or strains which were quite distinct on the
basis of their reaction to various media. It seemed probable
therefore that the species described in other coconut-growing
regions might be nothing but strains. Accordingly, various spe-
cies of Phytophthora which had been reported to attack palms
in other countries were collected. P. terrestris, which is com-
monly found on tomato fruits in Florida, also was obtained for
comparative studies.
The following cultures were compared:
81-Isolated from bud rotted palm, collected at Miami, Fla.,
by G. F. Weber and identified by him as P. faberi.
8K-Isolated from cacao fruit, collected in the Philippines,
by Otto Reinking and identified by him as P. faberi.
8L-Isolated from bud-rotted palm collected in Porto Rico by
C. M. Tucker and identified by him as P. palmivora.
8M-Received from Leonian; isolated from cacao pod, col-
lected in Jamaica by Ashby and identified by him as P. faberi.
8N-Received from Leonian; isolated from Borassus flabel-
lifer (Palmyra palm), collected in India by Hartley and Rein-
king and identified as P. palmivora.
8P-Received from Leonian; isolated from bud rotted coco-
nut, collected in Jamaica by Ashby and identified by him as
P. palmivora.
8Q-Received from Leonian; isolated from tomato fruit, col-
lected in Florida by Sherbakoff and identified by him as P. ter-
restris.
8Z-Isolated from tomato fruit, collected in Florida by G. F.
Weber and identified by him as P. terrestris.
119-Isolated from bud rotted coconut palm, collected at Palm
Beach, Florida by J. L. Seal and identified as P. faberi.
8X-Isolated from bud rotted coconut palm, collected at Palm
Beach, Florida by Seal. This organism and many others agree
with 81 and are considered to be identical with it. The remain-
ing Phytophthoras isolated from bud rotted palms are consid-
ered synonymous with 119, but of these there are comparatively
few in number.
The various organisms listed above were used in the labora-
tory and greenhouse in a general comparison as to their mor-
phology, physiology and pathogenicity. Single spore cultures







Bulletin 199, Coconut Bud Rot in Florida


were obtained by
picking up ger-
minating spores
with the aid of
a platinum needle
from poured
agar plates and
making transfers
to sterile media.
Stock cultures
were grown on
oatmeal agar and
moist, sterile
corn meal. Dupli-
cate cultures of
a 11 organisms
were kept, one
at room tempera-
ture (18-270C.)
and the other in
the ice box (16-
180C.). The stud-
ies made in the
laboratory were
not entirely sat-
isfactory, owing
to the nature of
the organism as
well as to the
lack o f equip-
ment for main-
taining absolute-
ly controlled con-
ditions. The or-
ganisms required
direct light in
order to form
conidia in abun-
dance, and the
temperature
under such con-
ditions f u c t u-


Fig. 7.-Curves showing the influence of media and
temperature on the rate of growth of strain 81
during a period of 96 hours. Corn meal agar
--o; Prune agar -


-ZH; M-i-


rTM. L W


[7AM flW4


4-I. i t,4 .I I IK


Fig. 8.-Curves showing the influence of media and
temperature on the rate of growth of strain 8K
during a period of 96 hours. Corn meal agar
o--o. Prune agar -.


I ] _T_ -1-1


.-


i 'I I I


-^:- ^.^


VL.T--^







Florida Agricultural Experiment Station


ated about three degrees C., but in studies where light was
not a factor the temperature was controlled within two degrees.
Inoculations
o :- were made in the
S.greenhouse, using
S-potted plants that
o were three to six
S.... years of age. Lar-
r70 ger plants could
not be used in the
Si / "-" greenhouse nor
were inoculation
experiments per-
mitted in the
Si field. The resist-
I -_..._. __ ....- ance of different
aged plants to
J the disease has
been the basis of
some discussion
',between Sharples
S i and Lambourne
Si (30) and Sunda-
L __ I raraman (35) in
oI- i| l78 T, 3~ which the for-
S- Deg ees C mer criticised the
latter for using
Fig. 9.-Curves showing influence of media and only young plants
temperature on rate of growth of strains 8L and
119 during a period of 36 hours. 8L on corn meal in his inocula-
agar o- o. 8L on prune agar --. 119 on tion experiments.
corn meal agar o--o. 119 on prune agar .--. d
Sundarara-
man (35) shows, in a more recent work, that adult trees suc-
cumb to the disease as readily as young plants. It is the pri-
mordal tissues in any case that are more readily susceptible to
the organism and in these undifferentiated tissues one would
find little, if any, differences, regardless of the plant's age.

PHYSIOLOGY OF THE CAUSAL ORGANISM
GROWTH ON VARIOUS MEDIA
As previously pointed out, all the different organisms react
differently to different media. Furthermore, the different strains







Bulletin 199, Coconut Bud Rot in Florida


of the same organism behave differently. When the various or-
ganisms were incubated in the light at 250C., the exceptionally
rapid growth of 119 and 8L was very noticeable, while 8Q was
conspicuous because it grew slowly. The amount of aerial my-
celium produced by 8N and 8Q is not so abundant as that pro-
duced by other organisms.
Just what factors cause the individual organisms to vary on
a given medium has not been determined, but one of the more
apparent causes
seems to be mois-
ture. On differ- -
ent media the -
various organ-
isms react differ-
ently, as one \
would expect,
not only in their
vegetative
growth but also
in spore produc-
tion. a-
The abundance -
of spores pro- o-
duced by the h
various organ-
isms on the vari- Fig. 10.-Curves showing the influence of media and
ous media is in- temperature on the rate of growth of strain 8M
during a period of 96 hours. Corn meal agar
dicated in Ta- o- -o. Prune agar x-x.
ble I.
In this table one will note the scarcity of spore production in
119; also the abundance of spores produced on oatmeal agar and
corn meal flour. Leonian (20), Reinking (28), Gadd (15), Tuck-
er (36), and others have made similar observations in their
studies of the Phytophthoras.

REACTION TO TEMPERATURE
In order to ascertain the effect of temperature on various
strains and species of Phytophthora, parallel series of cultures
on corn meal agar and on prune agar were kept at the following
temperatures: 110, 170, 220, 280, 32' and 38C. The various
temperatures were obtained in a battery of soil temperature








Florida Agricultural Experiment Station


TABLE I.-COMPARATIVE SPORULATION OF DIFFERENT STRAINS AND SO-
CALLED SPECIES OF Phytophthora, ON VARIOUS MEDIA, AT THE END OF'
ONE, TWO AND FOUR WEEKS.

One Week ITwo Weeks Four Weeks


Organism


81 P. faberi from Florida .................-
8K P. faberi from Philippines ..........
8L P. palmivora from Porto Rico......
8M P. palmivora from Jamaica ........
8N P. palmivora from India ..............
8P P. palmivora from Jamaica ........
8Q P. terrestris from Florida ..........
119 P. faberi from Florida ..........-

81 P. faberi from Florida ...............
8K P. faberi from Philippines ..........
8L P. palmivora from Porto Rico....
8M P. palmivora from Jamaica-.........
8N P. palmivora from India ......
8P P. palmivora from Jamaica ........
8Q P. terrestris from Florida ..........
119 P. faberi from Florida ................

81 P. faberi from Florida ................
8K P. faberi from Philippines ..........
8L P. palmivora from Porto Rico......
8M P. palmivora from Jamaica..........
8N P. palmivora from India ............
8P P. palmivora from Jamaica ........
8Q P. terrestris from Florida ..........
119 P. faberi from Florida ................

81 P. faberi from Florida ................
8K P. faberi from Philippines ..........
8L P. palmivora from Porto Rico......
8M P. palmivora from Jamaica..........
8N P. palmivora from India ............
8P P. palmivora from Jamaica ........
8Q P. terrestris from Florida .......
119 P. faberi from Florida ................

0-None.
1-Very scarce.
2-Scarce.


o 0 a 0 4
C) > C > c >


Potato Dextrose
1 2 2 2 2 2
2 2 3 3 3 3
0 0 1 0 1 1
2 2 3 3 3 3
0 0 1 0 1 1
2 0 4 1 4 2
2 0 3 2 3 3
0 0 1 1 1 1
Oat Meal Agar
1 2 3 3 I 3 3
2 3 3 4 3 4
1 1 2 2 2 2
3 1 4 3 4 3
1 0 2 0 2 0
3 3 4 4 4 4
2 2 3 3 3 4
S 0 1 1 1 1
Corn Meal Flour
2 2 3 2 3 3
3 3 4 3 4 4
2 3 3 4 3 4
3 3 4 4 3 4
1 0 2 0 2 0
3 3 4 4 4 4
2 2 3 3 3 4
0 0 0 1 0 1
Corn Meal Agar
2 2 3 3 2 3
2 2 3 2 2 3
2 0 2 1 2 2
2 2 3 3 2 3
1 0 2 0 2 1
2 1 3 2 2 3
1 0 2 1 2 2
0 0 1 1 1 1
3-Abundant.
4-Very abundant.


tanks in which soil cans were suspended in water. The tempera-
tures were regulated by thermostat-controlled kelvinator and
electrical heating units. The temperature did not vary more
than two degrees C. in each series. The media were prepared from







Bulletin 199, Coconut Bud Rot in Florida


dehydrated agars' in which the pH tested 6.8. Plates were poured
and held at room temperature for 24 hours, after which they
were inoculated. The inoculated plates were held at 25C. for
12 hours, at which time the contaminated plates were discarded
and the uncontaminated ones placed at the various temperatures.
Five plates of each organism were incubated at each tempera-
ture and measurements of each organism were made at intervals
of 12 hours up to the 96th hour. This experiment was repeated,
and, from the averages of the various diameters of each organ-
ism, curves were
plotted as shown
in figures 7 to 15. .! i
In these figures -
the rate of,
growth of the -- -
various orga n- i i [
isms is compared /
on corn meal
agar and prune -
agar. Very slight F'
growth was noted /
for all the organ- 7
isms at 110C.,
with the excep-
tion of 8P, which
made a percep-
tible growth on Fig. 11.-Curves showing the influence of media
corn meal agar. and temperature on the rate of growth of strain
8N during a period of 96 hours. Corn meal agar
(Fig. 12.) The o- -. Prune agar x- -x.
rate of growth
gradually increases with increased temperature up to 280C. and,
in some cases, up to 32C.
In 81, 8M, 8P and 8Q, the optimum vegetative growth is
reached at 280C; while in 8K the optimum lies between 28 and
320C; and in 8L, 8N and 119 the optimum is 320C. The maxi-
mum differs for the various organisms, extending from 320 to
'Manufactured by the Digestive Ferments Co.
Prune agar-20 grams dehydrated agar was added to 1000 cc. water and
autoclaved.
Corn meal agar-19 grams dehydrated agar was added to 1000 cc. wa-
ter and autoclaved.
Potato Dextrose-20 grams dehydrated agar was added to 1000 cc. wa-
ter and autoclaved.







Florida Agricultural Experiment Station


380C, the maximum depending upon the substratum on which
the organism is grown. On corn meal agar 8L and 119 grow
exceptionally well at 38, while the other organisms grow very
poorly at this temperature (see Fig. 9). On prune agar the
various organisms act, in general, very much like they do on
corn meal agar, with the outstanding exception of 8M, which
has its optimum between 22 and 28 instead of between 280
and 320C. The organism grew more vigorously on prune agar
than on corn meal agar, while the latter was conducive to a more
uniform growth
HPof the various
_0 organisms.
Reinking (28)
So reported the op-
timum tempera-
ture for growth
Sof 8K as lying
T I between 27 and
7---I 1/300C., being
S nearer 27. This
Discrepancy may
be due to the
I. substratum, as
Reinkihg's re -
Ssults were ob-
Stained on potato
To dextrose agar.

4 Ii 4j -- REACTION TO
Fig. 12.-Curves showing the influence of media and LIGHT
temperature on the rate of growth of strain 8P Light was ex-
during a period of 96 hours. Corn meal agar
o- -o. Prune agar. eluded from
the temperature
chambers and consequently very few conidia were produced in
any of the cultures. When they did occur, they were found in
cultures incubated at 22 to 32', with an occasional one in cul-
tures incubated at 170 and at 320C. Chlamydospores were not
formed because of the limited period of the experiments. The my-
celium was usually appressed or submerged at 110 and 170 and in
all cases the same condition prevailed at 380, with the exception
of 119 and 8L, where a fluffy growth was evident. All of the or-
ganisms produced an abundance of aerial mycelium between 220







Bulletin 199, Coconut Bud Rot in Florida


and 320 except in the case of 8M, in which the aerial mycelium
was very light
under the best of -i- !-----
conditions.

MORPHOLOGY
OF THE &
CAUSAL
ORGANISM S I
MYCELIUM -
There is not t

in the mycelium !
of the various i P J
strains, although "i- -
there are some
diffe re nces Fig. 13.-Curves showing the influence of media
diferenc and temperature on the rate of growth of strain
in quantity, size 8Q during a period of 96 hours. Corn meal
and uniformity agar o- -o. Prune agar 11- -11.
on various media. -
The aerial hy- -'- --
phae are color-
less, straight,
more or less uni- .
form in size,
branching freely, i
slightly con- -
stricted where -- -
branches arise --
from the older -./--
hyphae. The con-
tents of young -1
hyphae are ,
granular but be-
come vacuolated '
with age, and oil -I
globules are com- 7 '17 1, 21 Z, -
mon. Submerged -- eg, c I
mycelium may be
straight or r- Fig. 14.-Curves showing the influence of tempera-
straight or ir- ture on the rate of growth of the various strains
regular, smooth when grown on corn meal agar for a period of
96 hours. 81 o--o. 8K .--. 8L x--x. 8M
to uneven, x- x. 8P .-- 8Q 11- 11.






Florida Agricultural Experiment Station


gnarled or even warty, branching freely but irregularly, turn-
ing from hyaline to yellow and varying in diameter from 31 to
11t. The mycelium usually is non-septate when young but later
a few septa are formed in the vegetative as well as in the fructi-
fying hyphae. Mycelium is abundant in the host, intercellular
and sends fingerlike haustoria into the cells. (See Fig. 16.)
In plate cultures the first mycelial growth is submerged, but
after 24 to 48 hours aerial mycelium becomes visible. At first
it is very scant
but soon be-




~ merged myce-
S.lium is as de-
scribed abo ve
5 except that of
S8Q, which may
be warty. The





// 2/7 2 8 3 2 38 comes prone
Deyrees c and lightly to
heavily massed
Fig. 15.-Curves showing the effect of temperature heavily massed
on the rate of growth of the various strains on the surface
when grown on prune agar for a period of 96 of the su b-
hours. 81 o-o. 8K .- -. 8L x- -x. 8M
x--x. 8P .- 8Q 11--11. stratum. Con-
idia sometimes
are formed on the aerial mycelium within four days, but it is
usually about the seventh day before large numbers of the
spores are formed.
CONIDIOPHORES
The width of the conidiophores is less than that of the aver-
age mycelium, being only 3w to 8p, and more commonly about
5f. The conidiophores may be short or long, ranging from 150
to 750%.








Bulletin 199, Coconut Bud Rot in Floridd


Fig. 16.-Camera lucida drawings of section of bud rot tissues. A-Cross
section showing the intercellular mycelia. B-Tangential sections show-
ing a strand of intercellular mycelium. C-Tangential section show-
ing a strand of intercellular mycelium sending haustoria into one of
the host cells. (A and B x 250. C x 500.)







Florida Agricultural Experiment Station


The number of spores produced on a single conidiophore
varies from one to 20, but usually there are from five to 10.
Gadd (15) reports that the conidiophores of different strains
bear different numbers of spores. Usually there are from one
to eight branches and each branch bears only one spore, as
shown in Fig. 19. The type of sporophore branching varies
considerably in the various strains, as shown in figures 18 and
19. In most strains the sporophore is very compact, as the spores
are borne on short pedicels. In other strains the spores are
borne on exceedingly long pedicels and the sporophore is of a
spreading type. Reinking (28) does not note this latter type of
sporophore, but it is very clearly shown by Rosenbaum (29).
Spores are borne terminally and the mycelium continues its
growth as the spore is cut off with a short stalk or pedicel. The
best method found for studying the conidiophores is to stain
the organism while in a fructifying state in a petri dish. In
order to do this, the organism was killed by flooding it with
95 percent alcohol which was drained off after a few minutes;
and the culture was then stained with 1 percent acid fuchin,
washed with 50 percent alcohol and then with water. In such
preparations the conidiophores can be studied under the low
power of the microscope, while still on the medium or after hav-
ing been transferred to a slide.

CONIDIA
Conidia are produced terminally on the sporophores and, in
artificial cultures, may be abundant or completely absent. They
are oval to oblong With a papilla which is very prominent on
the more spherical ones and only slightly evident on the oblong
ones. (Figures 20 and 21.) The spores are generally attached
at the blunt end to the sporophore but occasionally this attach-
ment is at the side of the spore, as in Fig. 20.
Spores are shed from the sporophore with or without a pedi-
cel, which varies from 3 to 6, in length. (See Fig. 20.) The
spores are hyaline or only slightly yellow when young, multinu-
cleate, and finely granular, but they may become a distinct yel-
low on ageing, and may become vacuolate and coarsely granular
with many oil globules. The walls are thin and colorless at first,
but thicken and darken upon becoming old.




































Fig. 17.-Vegetative hyphae of different strains which give rise to the sporophores. A-Phytophthora
terrestris. B-P. faberi. C and D-P. palmivora. (All x 750.)






Florida Agricultural Experiment Station


CHLAMYDOSPORES
Chlamydospores are generally produced under all conditions
to which the various fungi have been subjected and are the most
common spore form under all conditions. They frequently occur
in diseased tissue and on artificial media, but their abundance
depends to a considerable degree upon the substratum upon
which the organism is grown. Light does not play the important
role in their development that it does in the development of
conidia. The chlamydospores are produced primarily in an inter-
cellular manner, but they may be produced terminally on short
branches which are perpendicular to the vegetative hyphae. The
shape may be irregular or perfectly spherical. Usually it varies
first in the diameter of one axis and then in the other and, upon
averaging the dimensions a large number of the spores, insig-
nificant difference is noted between measurements in diameter
of the two axes. While young they are slightly yellow to hyaline,
granular, slightly vacuolate, with a hyaline, thin wall, but as
the spore ages the color becomes yellow, and, in some instances,
turns to a light shade of brown, granulation becomes less uni-
form, vacuoles enlarge, and spore walls thicken to even twice
the original thickness.
OOSPORES
Oospores have not been found in any of the many artificial cul-
tures examined nor in any of the bud rotted specimens. If they
are formed in artificial media or in diseased plants, they must be
exceedingly rare. Rosenbaum (29), Reinking (28), Tucker (30),
and Butler (7) failed to find this spore form in the host or the cul-
ture media. Ashby (2) reports finding a few in host tissue,
while Gadd (15) was unable to find them in host tissues or in
artificial cultures of an individual strain. However, when he
placed two strains in the same culture, oospores were produced.
He therefore concluded that the organisms are heterothallic.
No attempt has been made in the present work to see if the
various strains would yield oospores under the above conditions.

SPORE MEASUREMENTS
Spore dimensions have been successfully used as a means of
delimiting species. This character, however, has proved to be
quite variable, the variability sometimes being due to a number
of different factors, including biologic forms with a Linnean




























;..-









Fig. 18.-CoAidiophores and conidia of different Phytophthora (x 375). A-P. faberi from the Phillippines.
B-P. palmivora from Jamaica. C-P. palmivora from India.






Florida Agricultural Experiment Station


species. Stakman and Levine (33) and Levine (22) have shown
that the biologic forms of Puccinia graminis Erikss. and lienn.
can be distinguished on the basis of spore size if sufficient spores
are measured, provided they were produced under normal and
uniform conditions. LaRue and Bartlett (18) have also dis-


7'


% T .\ ( ,



Fig. 19.-Conidiophores and conidia of different Phytophthoras (x 750).
A-P. faberi from Florida. B-P. palmivora from Porto Rico. C-P.
faberi from Jamaica.





Bulletin 199, Coconut Bud Rot in Florida


Fig. 20.-Types of conidia produced by the different Phytophthoras (x
750). A-P. faberi from Florida. B-P. palmivora from Jamaica. C-
P. faberi from India. D-P. faberi from Jamaica.


,(: N






Florida Agricultural Experiment Station


tinguished numerous strains of Pestalozzia guepini Desm. on the
basis of spore size. Burger (5) found a great difference in size
of spores of several strains of Colletotrichum gloesporioides
Penz., in which he observed that the medium had a marked ef-
fect on spore size, but did not necessarily affect each strain in
the same manner.
Leach (19), working with various biologic forms of Colleto-
trichum lindemuthianum (Sac. and Mag.) Bri. and Cav., con-
cludes that differences influenced by the culture media on spore
size were so great and that the difference between the various
strains in regard to spore size was so small that the results ob-
tained from spore measurements were of no practical value.
Gadd (15), working with six strains of Phytophthora faberi
Maubl., gives evidence that there are real differences in spore
sizes of these strains and that the conditions under which the
organism is grown, i. e. media, light, temperature, moisture,
aeration, etc., have some influence upon the spore size. Ashby
(2) states that age influences the size of spores. The first spores
produced by the organism are larger than those produced
later.
There is considerable difference in the spore dimensions of
the different Phytophthoras attacking the coconut palm, as
given by the various workers. These discrepancies may be ac-
counted for on the basis of variance of biologic forms, habitat,
climatic conditions, age, number of spores measured, experi-
mental error, etc.
In an effort to determine the limits of variation in spore size
of the Phytophthoras attacking the coconut palm, the organisms
were grown on four of the more common artificial media: po-
tato dextrose agar, oatmeal agar, corn meal agar, and sterilized
corn meal flour. The measurements were made of spores ob-
tained from cultures of the various strains of Phytophthora
which were grown on the same batch of media, incubated at the
same temperature, and measured at as near the same age of
development as possible. Conidial measurements were always
made as soon as enough spores had been formed in the culture,
in order to eliminate secondary conidia. The same microscope
and micrometer were used in making all the measurements.
Measurements were made at the interpupillary distance of
60 mm., with a 4 mm. objective, a 10X ocular and with the aid
of an eyepiece micrometer in which each division was equivalent






Bulletin 199, Coconut Bud Rot in Florida


- -.'

:
K '


Qai / ATR


A iA


^\ / 3


/A


Fig. 21.-A, Chlamydospores, showing method of production, shape and
germination (x 500). B, Terminal papillae from conidia of different
Phytophthoras. 1. P. faberi from Florida. 2. P. faberi from the Phil-
ippines. 3. P. faberi from Jamaica. 4. P. terrestris from Florida.
(x 500).






Florida Agricultural Experiment Station


to 1.571. Four or more mountings of the organism measured
were used and these were taken from different places of the
culture which were grown in test tubes. In order that the
samples of a given organism might be representative, 400 spores
of each spore type were measured; this number seemed to be
sufficient in most cases. As the ratio of conidial width to
length was to be determined, length and width of each spore
measured was noted. For length, the conidia were measured
from the tip of the papillum to the base, exclusive of the basal
stalk; the width was obtained by measuring the largest diam-
eter of the breadth of the conidia.
In the biometric studies calculations were made according to
the methods given by Babcock and Clausen (4). In order to in-
terpret the differences found in such a study it was necessary
to calculate the probable error of these differences and then es-
tablish relationship between the differences and their probable
errors. Rietz and Smith (25) make the following statement with
reference to the significance of the probable errors: "If the dif-
ference does not exceed two or three times the probable error,
the difference may be reasonably attributed to random sam-
pling. If the difference between the two results is as much as
five to ten times the probable error the probability of such dif-
ferences in random selection is so small that we are justified in
saying that the difference is significant." In the present study
a difference less than five times the probable error of this differ-
ence was considered questionable, and only differences as great
as or greater than five times the probable error were considered
as really significant.
In Table II is a summary of the spore measurements of all
the strains studied, when grown on the four different media
under conditions that were similar in all respects. In this table
the classes are arranged according to length and width of con-
idia, each class differing from the other by 1.57 microns. This
table also shows the number of spores falling into each class.
The chlamydospore dimensions are summarized in a similar
way in Table III.
Tables IV, V and VI are so arranged as to show the range of
variations in the spore dimensions and to give the constants
with their probable errors for the different spore types of the
different strains of Phytophthora grown on the same and on dif-
ferent substrata.






TABLE II. -FREQUENCY DISTRIBUTION ACCORDING TO SIZE OF CONIDIA OF CERTAIN STRAINS AND SrPE
POPULATION IN EACH C
jM


3IES
ABE

>dia


OF


Phytophthoraw GROWN ON
400 INDIVIDUALS.


Potato Dextrose Agar


____ ______ ____ __ ___ __ _11


Oat Meal Agar


I I


Corn MeE


Classes
According
to Length
and Width
in Microns


14.13
15.70
17.27
18.84
20.41
21.98
23.55
25.12
26.69
28.26
29.83
31.40
32.97
34.54
36.11
37.68
39.25
40.82
42.39
43.96
45.53
47.10
48.67
50.24
51.81
53.38
54.95
56.52
58.09
59.66
61.23
62.80
64.37
65.94
67.51
69.08
70.65
72.22
73.79
75.36
76.93
78.50
80.07
81.64
83.21
84.78
86.35
87.92
89.49
91.06
92.63


94.20
95.77


81


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Bulletin 199, Coconut Bud Rot in Florida


The probable error of the differences in the statistical results
obtained in this study are given in Tables VII and VIII. The
various strains are grouped according to the substrata on which
they were produced.
In figures 22 to 36 curves are plotted for spore dimensions
in microns. These graphs represent the variation in spore sizes
of the various strains when the organisms were grown on vari-
ous media and on the same media, but in either case under uni-
form environmental conditions.

TABLE III.-FREQUENCY DISTRIBUTION, ACCORDING TO SIZE OF CHLAMYDO-
SPORES OF CERTAIN STRAINS AND SPECIES OF Phytophthora GROWN ON
VARIOUS MEDIA BUT UNDER UNIFORM ENVIRONMENTAL CONDITIONS;
POPULATION IN EACH CASE =400 INDIVIDUALS.


(D Media


S PotatoDextrose Oat Meal Agar Corn Meal Agar
w ^4 Agar
-' IRT IRKtl8L 8MI8P| 8Q 8I18Kr8L!8M!8P|8QI 81 18K 8L!8MiS8P 8Q
15.70 ...... ...... ...... I 1 1 1 1 ............................ 1 ......1.........1 ............ ..............
17.27 .......... .... 3 1 2 1 ..... 0...... .. ..... ..... ..- ...-.. ... ---
18.24 ....... 1 7 1 5 3 2 .-.. ..... .... 1 .........--- 2 1
20.41 3 2 3 11 4 8 5 2 1 ...... 2 1 3 ...... .... 2 1...
21.98 8 4 3 19 4 14 6 3 1 1 3 2 3 1 1 5 1 1
23.55 14 9 6 28 11 29 12 4 2 3 5 4 5 2 3 8 4 2
25.12 24 5 12 39 26 47 25 7 8 5 17 6 9 4 4 22 8 4
26.69 38 10 19 35 41 54 32 10 19 4 27 15 12 7 20 22 11 12
28.26 42 23 21 41 52 56 39 15 23 5 38 21 21 9 25 32 14 14
29.83 38 28 24 52 54 50 45 13 34 10 38 24 20 6 33 391 191 22
31.40 41 28 37 48 57 37 43 18 571 17 42 34 40 10 51 34 311 28
32.97 45 29 41 33 52 31 50 24 561 30 51 40 54 11 67 48 441 34
34.54 53 32 51 26 31 16 335 571 37 47 42 57 16 79 34 57 49
36.11 27 33 45 28 27 17 31 38 59 43 49 41 51 27 53 40 53 50
37.68 25 42 44 13 17 11 231 42 37 49 36 39 45 29 29 26 55 46
39.25 14 37 31 8 12 8 20 43 21 55 23 37 37 36 20 31 38 33
40.82 16 34 21 3 4 7 16 39 14 56 8 34 21 57 7 21 28 27
42.39 7 23 2 2 2 4 7 29 6 31 7 18 11 43 3 19 19 24
43.96 3 258 2 1 2 3 21 3 29 3 13 7 47 2 10 9 19
45.53 1 18 6 1 1 1 1 22 1 10 1 10 2 26 2 3 5 13
47.10 1 9 3...... 1.... 1 9 1 6 1 6 1 17 1 1 1 11
48.67 ...... 4 ......... 7 ...... 4. 4 .-.- 13 .-- 1 1 6
50.24 ...... 2 1 ..... -. ...... -.....- 5 ...... 3 ...... 4 ...... 16 ...... ...... ...... 3
51.81 ..... 0 1 ...... .-.- .- .- --- 4 ...... 1 ...... 2 ...... 6 .................. 1
53.38 ...... 2 ....- ...... 2 ..... -- .- ...- 2 ...... 7 ................ 1
54.95 ... ..... .... .. .... ...... .... 1 ...... 3 ... .... ......
56.52 ...... 1 ........... -- 2 ...... ...... ...... .... 5 .. ... .....
58.09 ...... ....- ..- ..... ....- ...... ...... 1 ....... 2 ...... ---.- --.. -....
59.66 I.- .. .. ....- 1!-- ... -|-.. .. .... ...... ......
81-P. faberi from Florida 8M-P. faberi from Jamaica
8K-P. faberi from Philippines 8P-P. palmivora from Jamaica
8L-P. palmivora from Porto Rico 8Q-P. terrestris from Florida






TABLE IV.-VARIATIONS AND CONSTANTS FOR LENGTHS OF 400 CONIDIA OF STRAINS OF Phytophthoras GROWN ON VARIOUS MEDIA
UNDER UNIFORM ENVIRONMENTAL CONDITIONS.


Spore Classes According to Length in Microns
a g 4 C to DeviationI efficient
-4 .J ti ai uQ )d o6 Z Cl M m mean of
2, 4 1 M M 00 00 00 Mean Standard Variabilit
SP.A. ..... 3 9 15 28 551 85 90 60 27 16 9 3... ...... .......... .................. ... 39.13 .21 6.20 .15 18.39 .44
81 O.A. ........ 12 27 46 63 61 48 42 34 2722 9 6 ...........2 1..--------..-......-----.......43.38 .30 8.78 .20 19.43 .47
C.A. ...... 3 16 41 70 102 69 55 25 10 6 3 .------..-........-....- -- -- ----.... ------ ------... -.. ------.... -------.. ... 36.38 .20 5.83 .14 13.45 .32
C.F ............ ------ 9 14 14 39 54 78 70 46 37 17 12 7 2 0 1 .... ..... ..... ......... ......................... 43.11 .17 7.33-- .17 17.01 .40
P.A. .------ .....1 3 7 42 591 82 901 551 29 23 4 4 11 ...--...... ----......-- -.... ......-----............ 140.58 .21 6.09 .14 15.01 .36
8K O.A. ............1 1 3 8 9 30 52 62 69 541 52 27 16 8 4 2 1 1-----........................ 54.43 .26 7.63 .1614.02 .33
C.A- ...----..------ 6 41 82 3 80 54 24 12 6 1 1-------- ...... .... ..-- -... ------ ...... ......----- ...... ----...... -- -- 36.66 .18 .30 .1 14.45 .34
C.F. ...... ...... 4 7 20 33 46 53 83 62 37 25 9 8 5 4 1 ............------ ---------...... ---...... ...... 50.55 .27 7.90 .18 15.63 .37
P.A. ...... -----...... ---...... 9 28 88126 80 46 17 6 ..---- ........ ......-- -- .....--..... --......--...... ..... .............. ......----------- 39.00 .15 4.33 .10 11.13 .26
8L O.A. ...... 1 1 4 16 52 82 88 63 33 23 16 13 3 2 3 ...................------ ---- ............................. ----42.56 22 6.75 .16 15.85 .38
C.A. ---....- 1 4 5 10 25 52 94 80 58 38 19 12 2 .....-- ......................- ....--- ......... ......... ...... 42.65 .18 5.29 .12 12.64 .30
C.F. ...... ....................... 3 11 27 76 86 86 43 39 18 6 3 1 1 ............----.............................. 50.04 .19 5.67 .14 11.33 .27
P.A. ...... ...... 4 271 54 86 90 69 39 22' 6 31...... 41.30 .18 5.44 .13113.19. .31
8M O.A. 1 3 16 29 30 50 68 87 62 31 15 7 1 --...... .................. 39.91 .23 6.85 .16 7.16 .41
C.A. ......I...... -- 4 13 281 85 106 85 36 29 7 3 3 1 .. ...... ......-- ------ -----...... ...... 39.36 .18 5.46 .13 13.85 .33
SC.F. 11 5 10 28 40| 57 58 72 60 34 21 11 3........ ..................-- ------ I ---I -39.73 .24 7.14 .17 17.97 .43
O.A. I-I 3 21 48 76 70 66 51 29 14 11 6 1 1 .................. .... ............ 39.37 .23 6.48 .16 17.50 .41
8N C.A. .... .. 8 14 30 73 91 90 46 25 12 6 2 ........ .............-........3...... 39.73 .20 5.97 .14 15.03 .32
C.F. ............ 1 5 10 40 54 74 76 57 43 18 10 8 2 ----.....-- ---...........--------...... ...... ... ...- ...........-- ...... 42.56 .18 5.48 .14 12.88 .31
P.A .......... 1 5 19 44 85 79 70 53 26 11 3 3 1--------.........-.. .... .... .... ...... .......... 45.53 .20 5.98 .18 13.13 .31
8P O.A ..1 4 7 17 24 32 51 62 58 52 36 16 17 9 6 1 3 1 1 0 153.22.31 9.40.2717.66-.32
C.A. ...... 1 10 22 35 70 98 80 41 24 13 5 1.........----- -- ------------------........ ------............ ------............... 38.89 .20 5.94 .14 15.27 .39
C.F. ...... ............ 1 3 24 59 73 33 21 9 3 1 -- --.... ........................ 45.71 .22 6.65 .16 14.55 .34
P.A. ....-- .... 5 18 55 91 91 68 27 25 14 5 1.... ... .....-- ..... ..... .... -- ...... 38.86 .19 5.74 .13 14.77 .34
8Q O.A. 1 3 12 1 38 46 53 69 5 33 29 22 9 3 3 1--------------......----- ......------.................. 41.32 .27 8.02.1919.41 .23
SC.F. ............ ...... 11 1 45 7 60 45 37 13 3 3 ............ .... ........ .... ...... ...... 47.31 .25 7.29 .18 15.41 .37
81-P. faberi from Florida 8L-P. palmivora from Porto Rico 8N-P. palmivora from India 8Q-P. terrestris from Florida
8K-P. faberi from Philippinnes 8M-P. faberi from Jamaica 8P-P. palmivora from Jamaica
*P.A.-Potato dextrose agar. O.A.-Oat meal agar. C.A.-Corn meal agar. C.F.-Corn meal flour.





TABLE V.-VARIATIONS AND CONSTANTS FOR WIDTHS OF 400 CONIDI A OF STRAINS OF Phytophthoras GROWN ON VARIOUS
MEDIA UNDER UNIFORM ENVIRONMENTAL CONDITIONS.


stands

Coefficient
of Variability


ISpore Classes According to Widths in Microns Con
Media or
Strains Environmental 4 g g S g Mean Standard
Conditions Q L Dg M g t 0 4 4 Deviation

Potato dextrose agar.. ......... 7 40 126 136 70 17 4 ...-.......... 28.18--.12 3.49 .08
81 Oat meal agar ............. ..... 6 64 139 96 58 29 8 ..... ..... 27.27 .14 3.85 .09
Corn meal agar -.......... 79 146 118 41 7.... .......... .-... .. 23.19 .12 3.65 .09
Corn meal flour .. ........ 19 78152107 35 8 ........... 26.55 .11 3.40 .08
Potato dextrose agar .... 1 6 47 99143 79 19 6 ..... ............ 28.41 .12 3.68 .09
8K Oat meal agar ....... --.... .. 9 43 113 116 84 28 3 2 34.88 .13 3.97 .09
Corn meal agar ......... 1 36 142 119 63 32 5 1 ............ ..... 25.34 .12 3.67 .09
Corn meal flour .......... ..... ...... 2 26 92 142 102 30 6 ...... ...... 32.43 .12 3.46 .08
Potato dextrose agar.. ....... 45 208 125 15 3 .. ...... ....... 27.45 .11 3.19 .08
8L Oat meal agar ........ ...... 2 38137 133 66 17 5 2 ...... .... .... 25.16 .12 3.49 .08
Corn meal agar .......... ---... 3 14 66 132 103 56 20 5 1 .. 30.60 .14 4.02 .10
Corn meal flour .......... .... .... 52177114 43 8 ................. 30.31 .10 3.06 .07
Potato dextrose agar.. .... 2 24 95 143 97 28 10 1 .......... 29.00 .12 3.65 .09
8M Oat meal agar ............ ...... 7 26 57 117113 54 21 3 1 1...... 27.20 .15 4.36 .08
Corn meal agar ............. 1 8 79 176 80 46 7 3 ...... -........ 26.75 .11 3.27 .08
Corn meal flour --...-.| 1 2 18 69 1021118 60 26 4 ............ 27.64 .14 4.19 .10
Oat meal agar ............ 13 85129 94 55 18 5 ......... ...... 27.20 .14 4.07 .10
8N Corn meal agar .......... 1 9 43128 137 61 20 1 ...... .... ...... 27.95 .12 3.53 .08
Corn meal flour ....... ... .... 2 53153133 46 11 1 1........... 27.58 .11 3.17 .08
Potato dextrose agar.. .................. 10 65 164 110 39 11 1 .......... 30.15 .11 3.28 .08
8P Oat meal agar ............ ..... 3 17 113171 80 16 ......... ........ 28.70 .10 2.91 .07
Corn meal agar ........... 3 46 148 134 56 13............. .... ..... 24.60 .11 3.13 .08
Corn meal flour ............ 2 33131153 58 1 7 1 ..... ..... 28.09 .11 3.30 .08
Potato dextrose agar... 2 8 76 136 105 43 22 7 1 ..... ..... 27.66 .14 4.08 .10
8Q Oat meal agar ........... 1 6 25 50 94 74 67 46 28 8 1..... 32.06 .19 5.66 .14
___ Corn meal flour ...... .... 10 30 84 98 106 46 24 1 1 ..... 33.01 .15 4.54 .10


8I-P. faberi from Florida
8M-P. faberi from Jamaica
8Q-P. terrestris from Florida


8K-P. faberi from Philippines
8N-P. palmivora from India


8L-P. palmivora from Porto Rico
8P-P. palmivora from Jamaica


12.38 .29
13.82 .33
15.74 .38
12.81- .31
12.95 .29
11.38 .28
14.48-- .34
10.70 .25
11.63 .28
13.49 .32
13.14 .31
10.01 .24
12.59 .30
16.03 .38
12.22 .29
15.19 .36
14.96 .35
12.64 .30
11.49 .28
10.88 .27
10.14 .24
12.72 .30
11.39 .28
14.75 .35
17.65 .42
13.75 .32











TABLE VI.-VARIATIONS AND CONSTANTS FOR DIAMETERS OF 400 CHLAMYDOSPORES OF STRAINS OF Phytophthoras.
Spore Classes According to Diameters in Microns Constants
Media or
Strains Environmental q S g g Standard Coefficient .
Conditions 0 c a= q M S 40 0 V g 1 Mean Deviation of Variability &

Potato dex. agar.... 322 62 80 86 80 39 23 4 1 ............. 31.95 .18 5.23- .13 16.37 .39
81 Oat meal agar ..... 2 8 18 57 84 93 67 43 23 4 ..... 32.19 .18 5.41 .13 13.86 .33 %
Corn meal flour ...... 41 8 21 411 94108 82 32 9 1.-...... ..-- .- 34.31 .16 4.84 .12 14.16 .34 3.
Potato dex. agar....... 2 13 15 51 7 65 79 57 432 1...... 36.26 .21 6.31 .15 17.40 .42
8K Oat meal agar....... 4 7 17 28 42 73 8 68 43 9 4 3 1 37.87 .21 6.30 .15 16.64 .39 ,
S Corn meal flour -.....3 11 15 21 43 65 100 7330 22 10 7 41.04 .22 6.57 .16 16.01 .34
Potato dex. agar .....I 4 9 31 45 78 96 7 41 14 2...... ......34.66 .19 5.55 .13 16.01 .38M
8L Oat meal agar ....... 1 3 27 57113 6 58 20 4 1.... .......... 33.17 .14 4.02 .10 15.14 .36
_Corn meal flour ..... 4 241 58118132 49 10 4 1.............. 33.47 .13 3.94 .09 11.75 .28
Potato dex. agar. 418 4 7493 81 54 1 5 .... --....1.....I ............ 28.00 .14 4.07 10 14.54.35
8M Oat meal agar ... ........... 4 15 47 80 104 87 39 10 4...........37.89 .17 5.06 .12 13.35 32 .
Corn meal flour.... 4 13 44 71 82 74 57 40, 13 2 ...... ---.... ...... 33.39 .19 5.66 .14 16.95- .39
Potato dex. agar. 2 ...... 5 15 671106 109 58 29 6 ... ............ 30.89 .15 -4.56- .11 -14.76 .36
8P Oat meal agar ... 1...... 3 8 44 76 93 96 57 1 4 1 ................ 32.75 .16 4.74 .11 14.47 .34
Corn meal flour ...... ...... 2 5 19 33 75 110 93 47 14 2 ........... 35.38 .16 __4.83 .12 9.21 .23
Potato dex. agar. 3 ...... 13 431101108 66 33 191 11! 3 ...-- .....- .- .-... 28.14 .17I 5.13 .12 17.64 .42
8Q Oat meal agar ......... 1 6 21 45 74 83 76 52 23 10 6 3.... 35.97 .20 5.99 .14 16.65 .39
Corn meal flour ...... ...... 3 16 36 99 79 51 32 17 4 1...... 36.72 .19 5.66: .13 15.41 .37

8I-P. faberi from Florida 8K-P. faberi from Philippines 8L-P. palmivora from Porto Rico
8M-P. faberi from Jamaica 8P-P. palmivora from Jamaica 80-P. terrestris from Florida


-








Bulletin 199, Coconut Bud Rot in Florida


TABLE VII.-SUMMARY OF DIFFERENCES IN THE MEAN DIMENSIONS OF
CONIDIA OF 7 STRAINS BELONGING TO 3 SPECIES OF Phytophthora GROWN
ON 4 DIFFERENT CULTURE MEDIA UNDER UNIFORM ENVIRONMENTAL CON-
DITIONS.


Substratum


Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose
Potato dextrose


agar.
agar.
agar.
agar.
agar.
agar.
agar.
agar-
agar-
agar.
agar.
agar.
agar.
agar.
agar.


meal agar ..............
meal agar-..............
meal agar..............
meal agar..............
meal agar ..............
meal agar..............
meal agar-..............
meal agar-..............
meal agar..............
meal agar -..............
meal agar ..............
meal agar..............
meal agar-..............
meal agar..............
meal agar-..............
meal agar..............
meal agar..............
meal agar----.............
meal agar.............
meal agar ..........
meal agar..............


Difference
Strains (in M
Compared

Length

8P and 81 6.40 .29
8P and 8K 4.954 .29
8P and 8L 6.53: .25
8P and 8M 4.23 .28
8P and 8Q 6.67 .28
8P and 81 2.17 .28
8P and 8K .72 .28
8P and 8L 2.30 .24
8P and 8Q 2.44 .26
8K and 81 1.45 .30
8K and 8L 1.57 .26
8K and 8Q 1.52 .28
81I and 8L .13 .29
81 and 8Q .27 .28
8L and 8Q .14 .24


.
.
.
.
.
.
.
.
.
.
.
.
.
.
.


I


10.84 .43
1.21 .41
10.66 .38
13.31 .39
13.89 .39
12.90 .41
11.05 .33
.82 .34
3.47 .38
4.01 .38
2.06 .40
2.65 .32
3.19 .32
1.24 .35
11.89 .34
13.11 .38
1.41 .35
1.95 .35
14.52 .35
.54 .33
15.06 .35


Differences in
s in Means Means Divided
s in Means by Probable
icrons) Error of the
Differences


Width ILengthl Width

1.97 .16 22.17 12.31
1.74 .16 17.07 10.88
2.70 .16 26.12 16.88
1.15 .16 18.39 6.56
2.49 .18 24.18 13.83
.82 .17 7.75 4.82
.59 .17 2.64 3.49
1.55 .16 9.58 9.69
1.34 .18 9.39 7.44
.23 .17 4.83 1.30
.96 .16 6.08 6.00
.75 .18 5.43 4.17
.73 .16 .45 4.56
.52 .18 .96 2.89
.21 .18 .58 1.17

.52 .16 25.21 3.25
6.18 .16 2.95 3.63
3.54 .16 28.53 22.13
1.50- .18 34.13 8.33
.50 .17 36.90 8.82
3.36 .21 31.46 16.00
7.61 .19 33.48 40.05
3.02 .17 2.41 17.77
.98 .19 9.13 5.16
.98 .18 15.53 5.44
3.88 .22 5.02 18.00
2.04 .19 8.28 10.70
2.04 .18 9.97 11.33
6.90 .25 3.54 27.60
9.72 .20 34.97 48.50
2.82 .23 34.50 12.26
4.86 .24 4.03 20.25
4.86 .26 5.57 18.46
7.60 .20 41.48 38.00
.00 .00 1.64 .00
7.68 .19 43.03 40.42


81-P. faberi from Florida
8L-P. palmivora from Porto Rico
8N-P. palmivora from India
8Q-P. terrestris from Florida


8K-P. faberi from Philippines
8M-P. faberi from Jamaica
8P-P. palmivora from Jamaica


8P
8P
8P
8P
8P
8P
81
81
81
81
81
8L
8L
8L
8L
8Q
8Q
8Q
8N
8N
8N


and 81
and 8K
and 8L
and 8M
and 8N
and 8Q
and 8K
and 8L
and 8M
and 8N
and 8Q
and 8M
and 8N
and 8Q
and 8K
and 8K
and 8M
and 8N
and 8K
and 8N
and 8K


I







Florida Agricultural Experiment Station


TABLE VII.-SUMMARY OF DIFFERENCES IN THE MEAN DIMENSIONS OF
CONIDIA OF 7 STRAINS BELONGING TO 3 SPECIES OF Phytophthora GROWN
ON 4 DIFFERENT CULTURE MEDIA UNDER UNIFORM ENVIRONMENTAL CON-
DITIONs.-Continued.


Differences in Means
(in Microns)


Length Width


Substratum


Strains
Compared




8L and SI
8L and 8K
8L and 8M
8L and 8N
8L and 8P
8N and 8I
8N and 8K
8N and 8M
8N and 8P
8M and 8I
8M and 8K
8M and 8P
8P and SI
8P and 8K
8I and 8K

8L and 81
8L and 8K
8L and 8M
8L and 8N
8L and 8P
8L and 8Q
8Q and 8I
8Q and 8K
8Q and 8M
8Q and 8N
8Q and 8P
8P and 8I
8P and 8K
8P and 8M
8P and 8N
8I and 8K
8I and 8M
81 and 8N
8N and 8K
8N and 8M
8M and 8K


Differences in
Means Divided
by Probable
Error of the
Differences
ILengthl Width


23.22
23.96
13.16
11.68
13.93
19.52
23.60
1.37
3.00
11.07
10.80
1.74
8.96
8.63
1.04

23.90
1.55
33.22
28.77
14.97
8.81
11.67
8.53
21.54
15.32
4.85
7.65
13.83
18.69
11.25
19.32
9.66
1.72
24.21
9.43
30.06


41.17
28.28
21.39
14.72
33.33
28.00
15.53
7.50
21.94
16.00
8.81
14.33
8.81
7.88
12.65

25.07
13.25
9.23
13.65
14.80
15.00
34.00
3.05
26.86
28.53
25.89
15.88
27.12
2.25
3.19
36.75
5.45
6.44
30.31
.30
26.44


8I-P. faberi from Florida
8L-P. palmivora from Porto Rico
8N-P. palmivora from India
8Q-P. terrestris from Florida


8K-P. faberi from Philippines
8M-P. faberi from Jamaica
8P-P. palmivora from Jamaica


7.41 .18
5.11 .18
3.85 .18
2.65 .18
6.00 .18
4.76 .17
2.64 .17
1.20 .16
3.35 .16
2.56 .16
1.41 .16
2.15 .15
1.41 .16
1.26 .16
2.15 .17

3.76 .15
2.12 .16
1.57 .17
2.73 .20
2.22 .15
2.70 .18
6.46 .19
.58 .19
5.37 .20
5.43 .19
4.92 .19
2.54 .16
4.34: .16
.45 .20
.51 .16
5.88 .16
1.09: .20
1.03: .16
4.85..16
.06 .20
4.76 .18


Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn

Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn
Corn


6.27- .27
5.99 .25
3.29 .25
2.92 .25
3.76 .27
5.27 .27
5.90 .25
.37 .27
.84 .28
2.97 .27
2.70t .25
.47- .27
2.51 .28
2.23 .27
.28 .27

6.93 .29
.51 .33
10.31 .26
7.48 .26
4.33 .29
2.73 .31
4.20 .36
3.24 .38
7.54 .35
4.75 .31
1.60 .33
2.60 .34
4.84 .35
5.98 .32
3.15 .28
7.44 .38
3.38 .35
.55 .32
7.99 .33
2.83 .30
10.82 .36


agar ...........-
agar-............
agar ............
agar............
agar-............
agar............-
agar-............
agar-............
agar............
agar............
agar............
agar............
agar............
agar............-
agar............-

flour ..........
folur ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour ..........
flour .........
flour ........
flour ..........
flour .........-
flour ..........
flour ..........
flour .--.......
flour ..........








TABLE VIII.-SUMMARY OF DIFFERENCES IN THE MEAN DIAMETERS OF CHLAMYDOSPORES OF 6 STRAINS BELONGING TO 3
Phytophthora SPECIES GROWN ON 3 DIFFERENT CULTURE MEDIA UNDER UNIFORM ENVIRONMENTAL CONDITIONS.


Potato Dextrose Agar
--Diameter
Strains Differ'nce
Compared Difference Divided
in Means by
(in Microns) Probable
Error
8K and 8L.......... 1.66 .28 5.93
8K and 81.......... 4.31 .28 15.39
8K and 8P.......... 6.37 .26 24.50
8K and 8Q.......... 7.12 .27 26.37
8K and 8M.......... 8.24 .25 33.04
8L and 81.......... 2.71 .26 10.42
8L and 8P.......... 3.77 .24 15.71
8L and 8Q.......... 5.54 .25 27.16
8L and 8M........ 6.66 .24 27.75
81 and 8P.......... 1.061.23 4.61
81 and 8Q.......... 2.81 .25 11.24
81 and 8M........ 3.95- .23 17.17
8P and 8Q.......... 1.75-- .23 7.61
8P and 8M ........ 2.89 .21 13.76
8Q and 8M ........I 1.14 .22 I 5.02

8I-P. faberi from Florida
8M-P. faberi from Jamaica


Strains
Compared


Oat Mea
Diam

Difference
in Means
(in Microns)


8M and 8K .... .02.27
8M and 8Q.......... 1.91 .26
8M and 8L .......... 4.72 .22
8M and 8P ---...... 3.24 .23
8M and 81 .......... 5.70 .25
8K and 8Q.......... 1.90 .29
8K and 8L.......... 4.70 .25
8K and 8P .......... 5.14 .26
8K and 81 .... 5.68 .28
8Q and 8L ......... 2.80 .24
8Q and 8P .......... 3.22 .26
8Q and 81.......... 3.78 .27
8L and 8P ....-.... 42 .21
8L and 81......... .97 .23
8P and 8I ..........I .56 .24

8K-P. faberi from Philipj
8P-P. palmivora from Ja


1 Agar Corn Meal Flour
eter Diameter_
Differ'nce Strains Differ'nce
Divided Compared Difference Divided
by in Means by
Probable (in Microns) Probable
Error Error
.07 8K and 8Q.......... 4.32 .24 14.90
7.35 8K and 8P.......... 5.66 .27 20.96
21.45 8K and 81 .......... 6.73 .27 24.93
14.09 8K and 8L.......... 7.59 .26 29.12
22.80 8K and 8M ........ 7.64 .29 26.38
6.55 8Q and 8P......... 1.34 .25 5.36
18.80 8Q and 81.......... 2.41 .25 9.64
19.77 8Q and 8L.......... 3.25-- .23 14.13
20.29 8Q and 8M........ 3.33 .27 12.33
11.67 8P and 81 .......... 1.07- .23 4.65
12.39 8P and 8L..... 1.89 .21 9.09
| 14.00 8P and 8M....... 1.99 .25 7.96
2.00 81 and 8L ....... .84 .21 4.00
4.70 81 and 8M........ .92 .25 3.68
2.33 8L and 8M ........ .08- .23 | .35
pines 8L-P. palmivora from Porto Rico
maica 8Q-P. terrestris from Florida

























































1335 1649 1863 2.27 25.91 2905 3219 353J 384f 41.61
MICRO/VJ
Fig. 22.-Lurves showing the differences in length (upper) and width
(lower) of conidia of strain 81 when grown on various culture media
under uniform cultural conditions. .-. Potato dextrose agar, mean
length 39.13 0.21, mean width 28.18 0.12; x- x Oatmeal agar,
mean length 43.38- 0.30, mean width 27.27- 0.14; o--o Corn meal
agar, mean length 36.38 0.20, mean width 23.19 0.12; .- Corn
meal flour, mean length 43.11 0.26, mean width 26.55 0.11.






Bulletin 199, Coconut Bud Rot in Florida


EFFECT OF DIFFERENT CULTURE MEDIA ON SPORE SIZE
As previously stated, no two workers seem to agree on the
size of the conidia and chlamydospores produced by the various
organisms which cause coconut bud rot. From the number of
factors that might affect the size of the spore, one can readily
see why this condition exists. The greatest variation occurs in
the larger spore dimensions and is clearly shown by the effect
of the media on spore length. There is also great variation in
the diameter of the chlamydospores of the several strains of


Fig. 23.-Curves showing the differences in di-
ameters of chlamydospores of strain 81 when
grown on various culture media under uni-
form cultural conditions. .- Potato dex-
trose agar; mean diameter 31.95 0.18.
x-x, Oatmeal agar; mean diameter 32.19
0.18. -. Corn meal flour; mean diameter
34.31 0.16.


Phytophthora stud-
ied when cultured on
three different me-
dia. In general, there
is more variation in
the diameter of
chlamydospores than
in the width of con-
idia, but less so than
in their length.
Phytophthora fab-
eri from Florida
(81). --Conidia of
this strain when pro-
duced on oatmeal
agar averaged 71A
longer than those
produced on corn
meal agar. The nar-
rowest as well as the
shortest conidia were
produced on the lat-
ter substrata. The
broadest conidia, on
the other hand, were
produced on potato
dextrose agar. There


appeared to be a significant difference in the size of chlamydo-
spores of strain 81 when grown on potato dextrose agar and
corn meal agar and oatmeal agar, respectively.
Phytophthora faberi from the Philippines (8K).-In the case
of strain 8K, as in the case of strain 81, the longest conidia were





Florida Agricultural Experiment Station


T I-]-


9 *. vi \ 'i .!


jo i
i i I- ---





0 A / '- J -
0 '\-. .... \_ ; j |x!_ __ !_ I -_

76 j 2



ri7P 0 ..";
I VI J

Al I
.377 .^ki9 I-



7 :/ 1- .. H -_ -. ",
"' .. -, l A_
-,_ | -. ..



p:. ". -i ,I :'9
IC ,' -+
>. ..... 'T:. .X / ,
...I* ~ ': it:t. '* ," !\~7 :' .T ': "r... .7:^



--"--^-,,:. At_{,t,_
.
... .,": '" ,,;,"'\ ,
.A-- ." '- ..A, ,..
-_:, =--_ ..-7 -.. F -i.. fp. '"_'\- L : '_--.


.-.*.s -_I-t i ,u ai.- r a 90u
-. ,-....- .. /lCzOA'J


? 3 WJ JB34 4161 4A73


Fig. 24.-Curves showing the difference in length (upper) and width
(lower) of conidia of strain 8K when grown on various cultural media
under uniform cultural conditions. .-- On potato dextrose agar;
mean length 40.58- 0.21. x- -x. Oatmeal agar; mean length 54.43
0.26. o-- -o Corn meal agar; mean length 36.66 0.18 -
Corn meal flour; mean length 50.55- 0.27. .- Potato dextrose
agar; mean width 28.41 0.12. x-- -x Oatmeal agar; mean width
34.88 0.13. x- -x Corn meal agar; mean width 25.34- 0.12. .
Corn meal flour; mean width 32.43- 0.12.








Bulletin 199, Coconut Bud Rot in Florida 43

produced on oatmeal agar and the smallest ones on corn meal
agar, but the difference in the mean length was 17.77u, a dif-
ference of approximately 50 percent. Furthermore, unlike
strain 8I the spore width of 8K was most favorably influenced
by the same substrata as the latter's conidia length, i. e. by oat-
meal agar. The narrowest conidia were produced on corn meal
agar, on which the conidia of 8I were also the shortest. In the
case of chlamydospores the largest spores were produced on
corn meal flour, and the smallest ones on potato dextrose agar.


"205 "2.19 s. i 147- 6. *
. V151, C 0 /VS


'1V qi)J 4: -"731 6045 6359


Fig. 25.-Differences in diameters of chlamydospores of strain 8K
when grown on various culture media under uniform cultural con-
ditions. .--., on potato dextrose agar; mean diameter 36.26
0.21. x- -x, on oatmeal agar; mean diameter 37.87 0.21.
., on corn meal flour; mean diameter 41.04 0.22.

Phytophthora palmivora from Porto Rico (8L).-The conidia
of this strain were shortest on potato dextrose agar and long-
est on corn meal flour. They were narrowest on oatmeal agar
and widest on corn meal agar, although there was very little
difference in width between those grown on corn meal agar and
corn meal flour. The greatest difference in the chlamydospore
size of this strain was noted on potato dextrose agar and oat-



































S a m w 0. -m m' d 3 '
.60 -- 01 F on o a e- w -o,





I /
40-


.*i 40-





M1,0 !;.135 41 W Q5 .66, 693 no, 5 164 19W tZ7 1591 M MJA 314. 4161 44.75

Fig. 26.-Curves showing the differences in length (left) and width (right) of conidia of strain SL when grown on various culture
media under uniform cultural conditions. .- ., on potato dextrose agar; mean length 39.00 0.15 x- -x, on oatmeal agar;
mean length 42.56 0.22. o- -o, on corn meal agar, mean length 42.65 0.18. -. on corn meal flour; mean length 50.04-
0.19.- on potato dextrose agar; mean width 27.45- 0.11 x- -x, on oatmeal agar; mean width 25.16 0.12. o- -o, on
corn meal agar; mean width 30.60--L 0.14..--, on corn meal flour; mean width 30.31 0.10.







Bulletin 199, Coconut Bud Rot in Florida


meal agar culture; the spores in the former media exceeding
those in the latter by about 1.51,.
Phytophthora faberi from Jamaica (8M).-There appeared
to be very little variation in spore length of strain 8M on the
different culture media. The variation was somewhat greater in
the width of the
conidia on the dif-
ferent media is/
and in a few /___-/
cases fairly sig- -
nificant. Very e r
pronounced and /o0
undoubted- 90--
ly highly signifi- 0 /\
cant differences c \
r4 70
appeared in the 0
size of the 60--
chlamydo- M so/
spores of this p _
strain when Z
grown on differ- 3
ent culture me- 2o--
dia. The differ- il\
ence was especial- __. 4 4 5
ly great between 19 Z. 9 5 MICRONS89
M/CRON5
the chlamydo- Fig. 27.-Differences in diameters of chlamydo-
spores produced spores of strain 8L when grown on various cul-
o ture media under uniform cultural conditions.
on potato dex- .-- ., on potato dextrose agar; mean diameter
trose agar and 34.66- 0.19. x- -x, on oatmeal agar; mean
diameter 33.17 0.14. -., on corn meal flour;
oatmeal agar, a mean diameter 33.47 0.13.
difference of al-
most 10 in favor of the spores grown on the last named media.
Phytophthora palmivora from India (8N).-The different me-
dia exerted considerable variation in the length of the conidia of
this strain, the longest conidia being produced on corn meal flour
and the shortest on oatmeal agar. Very little difference in length
was noted on the conidia produced on oatmeal agar and corn meal
agar. No great difference appeared in the conidia width of this
strain on the different media. Unfortunately strain 8N did not
yield sufficient conidia on potato dextrose agar to permit spore







Florida Agricultural Experiment Station


4
j/ I
I .' ,-' it
60 -_ /; ..| ,. I^-- -- -



I -/ .. -


'~7^ ';!^!-i ~7
,_ ..i ... I, I

4 1 I i I-I-
- I




..,4 ', 5W 1
22.27 tiai 2 '0S 3 '9 -[ ti" 4ll61 4475 C'3 5iCd .4l' 1,. 605 &i 5-~


.160 -- -,-
150_-. H ,
140"- -- --



3J. -.
110 -7'/ '\
S '/ \


I i '

40--
,-/ L



-035 1649 9.6 22 259r 2905


. I 35M. r. 4161 4475
2 ,iS9 3533 34r 4i6I 4475


Fig. 30.-Curves showing the differences in length (above) and width
(be'ow) of conidia of strain 8N when grown on various culture media
under uniform cultural conditions. x- -x oatmeal agar; mean length
39.37- 0.23. o- -o, corn meal agar; mean length 39.73- 0.20.
.- -., corn meal flour; mean length 42.56- 0.18. x- -x, oatmeal
agar; mean width 27.20 0.14. o- -o, corn meal agar; mean width
27.95 0.12. .- -., corn meal flour; mean width 27.58 0.11.





































la IZO -c'-- .-




do
50











.At/C ON

Fig. 31.-Curves showing the differences in length (above) and width
(below) of conidia of strain 8P when grown on various cultural media
under uniform cultural conditions .-., potato dextrose agar; mean
length 45.54- 0.20. x--x, oatmeal agar; mean length 53.22t 0.31.
o--- o, corn meal agar; mean length 38.89- 0.20..---. corn meal f-our;
mean length 45.71i 0.22. .--., potato dextrose agar; mean width
30.15- 0.11. x-- -x oatmeal agar; mean width 28.70- 0.10. o----o,
corn meal agar; mean width 24.609 0.11. o- -o, corn meal flour;
mean width 28.09 0.10.
mean width 28.09 0.10.






Florida Agricultural Experiment Station


Phytophthora terrestris from Florida (8Q).-A very large
variation in spore size of this organism occurred on the differ-
ent media. Both conidia and chlamydospores were affected by









-17 -



50

-4o \-I--













potato dextrose agar; mean diameter 30.89 0.15. x- -x, oat-
meal agar; mean diameter 32.75- 0.16. .--- corn meal flour; mean
diameter 35.38- 0.16.


and potato dextrose agar the shortest. The same was true re-
garding the width of the conidia and the diameter of the
chilamydospores.

COMPARATIVE SIZE OF SPORES OF DIFFERENT STRAINS ON
THE SAME MEDIA
In order to determine whether or not the different species and
strains of phytophthora studied differ from each other in a sig-
strains of phytophthora studied differ from each other in a sig-








Bulletin 199, Coconut Bud Rot in Florida


I T.I I I I'
OJ5 1648 563 W I77 .51 282 3281 .X.3
Af/CRO/VJ


Fig. 33.-Curves showing the differences in length (above) and width
(below) of conidia of strain 8Q when grown on various culture media
under uniform cultural conditions. .--., potato dextrose agar; mean
length 38.86 0.19. x- -x, oatmeal agar, mean length 41.32 0.27.
S- -., corn meal flour; mean length 47.31- 0.25. .- potato dex-
trose agar; mean width 27.66 0.14. x- -x, oat meal agar; mean
width 32.06 0.19. corn meal flour; mean width 33.01 0.15.







Florida Agricultural Experiment Station


nificant way as far as the size of the conidia and chlamydospores
are concerned, various strains were cultured on different cul-
ture media under virtually identical environmental conditions.
Comparisons were made between cultures of the different strains
grown on the same media and of the same stage of development.
Ito

100 ___ _





W 70 I
60 --_- ,


s o- -^ Mv-
4o ----- y ---~ ~ ~//-\ V -- -

50 ^\


1640 19.63 2.77 Z591 29.05 32.19 3533 J.847 4161 4475 4789 51.03 54.17 57J3
/WC/PC/KJ
Fig. 34.-Differences in diameters of chlamydospores of strain 8Q when
grown on various culture media under uniform cultural conditions. .- .,
potato dextrose agar; mean diameter 28.14 0.17. x--x, oatmeal
agar; mean diameter 35.97 0.20.. -., corn meal flour; mean diam-
eter 36.72 0.19.

The results are recorded in Tables VII and VIII, and illustrated
in figures 35 to 41. A more or less detailed discussion of the
results obtained follows:
ON POTATO DEXTROSE AGAR.-Significant differences in both
length and width of conidia occurred on potato dextrose agar.
The difference was very pronounced in both dimensions and ap-
peared to be statistically significant. The greatest difference was
noted in the conidial length of strains 8P and 8Q, the former ex-
ceeding the latter by 6.67 0.28/. In the case of conidia width












It-
S I -

'.. ". -'- ..srai 8 mean l .5-- 0_21 .. ^ .------nM malh 410- 01 i ea
"I i"I I 'T ,1 !//! I\ ---


S '/ 3 1, i g 8 .8 .t"ain' i-
S- --L- -- ....



26 S7 0" IS5,t 3.OS .t3 3533S 3 .T4 44.75 B89 5B03 M.7 iZ31 6045159 6673(687 r W a.oJ .7.' 601 ..'ga5 K1l 55J3 i.e 4y um '1

Fig. 35.-Curves showing the differences in length (left) and width (right) of conidia of various Phytophthora strains
when grown on potato dextrose agar under uniform cultural conditions, o- -o, strain 81; mean length 39.13 0.21.
S- -., strain 8K; mean length 40.58 0.21. .---., strain 8M; mean length 41.30 0.18. .-- ., strain 8P; mean
length 45.53- 0.20. 1:1--1:1, strain 8Q; mean length 38.86 0.13. o--o, strain 8I; mean width 28.18 0.12. ---
strain 8K; mean width 28.41- 0.12. .---., strain 8L; mean width 27.45 0.11. x- x strain 8M; mean width
29.00 0.12. .- ., strain 8P; mean width 30.15 0.11. 1:1-- 1:1, strain 8Q; mean width 27.66 0.14.








Florida Agricultural Experiment Station


the greatest difference occurred between strains 8P and 8L,
amounting to 2.70 0.16/ in favor of 8P. By far the largest
chlamydospores in this experiment were produced by strain 8K
and the smallest ones by strain 8M. Strains 81, 8L and 8Q were
practically identical as far as conidial length is concerned; and
there was hardly any difference in conidial width of strains 81
and 8K on the one hand and 8L and 8Q on the other hand. More

uc-------ii ------- i --- --
DO---------------^ -----
90










cutualcndtins \-,trin8I mea -imee 319- 8
-- S------















curedwhn he wrculturedd- o, n omeal diametr. A 1.95 0.1i- .
50 ---- 0




10 -- --- -/ l -- ~ _^ __ __ _


a s s 16.40w 6 22.7 1 5. 0 9 tis Z9,03 s s J 8 4161 47s m 3M 5a .7 573 1 6i w45

Fig. 36-Differences in diameters of chlamydospores of the various Phy-
tophthora strains when grown on potato dextrose agar under uniform
cultural conditions. o- -o, strain 81; mean diameter 31.95t 0.18.
---., strain 8K; mean diameter 36.26 0.21. .- -., strain 8L; mean
diameter 34.66 0.19. x- x, strain 8M; mean diameter 28.00 0.14.
--., strain 8P; mean diameter 30.89 0.15. 1:1-1:1, strain 8Q;
mean diameter 29.14 0.17.

or less significant differences prevailed between the chlamydo-
spores of the various strains when cultured on potato dextrose
agar.
ON OATMEAL AGAR.-The greatest difference in length, but not
in the width, of conidia of the Phytophthora causing bud rot oc-
curred when they were cultured on oatmeal agar. As great a dif-
ference as 15.06 0.35/% occurred between strains 8N and 8K; 8K
having the longest conidia on this media. The latter strain had
the broadest conidia, while 8L had the narrowest ones, with a
difference of 9.72- 0.20a. Strain 8K shared the honor of hav-







Bulletin 199, Coconut Bud Rot in Florida


L^-Ptr -L-m _I I i- i- i-1
.'4 .r.2t ;. ",a 2li Jr ,.C J,,47 4W *4W s_ J" X,. W 4W,8r

Fig. 37.-Curves showing the differences in length (above) and width (be-
low) of conidia of various Phytophthora strains when grown on oatmeal
agar under uniform cultural conditions, o- -o, strain 81; mean length
43.38"- 0.30. -., strain 8K; mean length 54.43- 0.26. .- -., strain
8L; mean length 42.56-- 0.22. x-- x, strain 8M; mean length 39.91-
0.23. .- -, strain 8N; mean length 39.37 0.23. .- ., strain 8P;
mean length 53.22-- 0.31. 1:1- 1:1, strain 8Q; mean length 38.86
0.19. o- -o, strain 81; mean width 27.27- 0.14. ., strain 8K;
mean width 34.88 0.13. .- -, strain 8L; mean width 25.16 0.12.
x- x strain 8M; mean width 27.20 0.15. x---x, strain 8N; mean
width 27.95 0.12. .-- ., strain 8P; mean width 28.70 0.10. 1:1-1:1,
strain 8Q; mean width 32.06 0.19.






Florida Agricultural Experiment Station


ing the largest chlamydospores on oatmeal agar with strain
8M. The chlamydospores of these two strains were practically
identical. Strain 8I had the smallest chlamydospores of all, but
not significantly smaller than those of strain 8P.
ON CORN MEAL AGAR.-The greatest difference between the
conidial length of any two strains of coconut bud rotting organ-
isms grown on corn meal agar occurred between strains 81 and


tua cond|tion. --- -- --------------,-----1--- --- --- --- -- --- ----



1i- -- 7---7T 0---.a8mdm




K r------ ,-, ,.u^.,-,\-^-----------,--
J/- 4 .... -








1.i i6S S 2r .in 83l 25 ld 6 J iU 3 847 4 fe 4on get b51.u i llaJTJl t1W45 wJ,9

Fig. 38.-Differences in the diameter of the chamydospores of the various
Phytophthora strains when grown on oatmeal agar under uniform cul-
tural conditions, o- -o, strain 81; mean diameter 32.19 0.18. .--,
strain 8K; mean diameter, 37.87 0.14. .-- -., strain 8L; mean diam-
eter, 33.17 0.14. x-- x, strain 8M; mean diameter 37.89 0.17. .- .,
strain 8P; mean diameter 32.75 0.16. 1:1- 1:1 strain 8Q; mean
diameter 36.72 0.19.

8L, with a difference of 6.27- 0.27u in favor of strain 8L. How-
ever, this difference must be considered as highly significant
statistically, since it exceeds its probable error by more than
23 times. Strain 8L had not only the longest but also the widest
conidia, and, similarly, strain 81 had both the shortest and the
narrowest conidia. The difference in the conidial width of these















o -


40







I'/CR c -





IN/S
^"-7-/--^ t-








V ,' I. \k
0--f If., .--

























length 76.381 0.20. .- -. strain 8K; mean length 36.66-- 0.18...
strain 8L; mean length 42.65e 0.18. x-lx., strain 8M; mean length
9.36-tow) of conidia 0.18. x---various topx, strain 8N; mean length 9.7 0.20. .orn
strain 8P; mean length 38.89 0.20. o- -o, strain 81; mean width
23.19 0.12. .---., strain 8K; mean width 25.34 0.12. .---., strain
8L; mean width 30.60 0.14. x- x, strain 8M; mean width 26.75
0.11. x-----x., strain 8N; mean width 27.95-- 0.12. .- ., strain 8P;
mean width 24.60- 0.11.







Florida Agricultural Experiment Station


.,o -I/ ) ,- ,-,
.0 1,1 / / / 1A

00___ fJl -_._
go---- ----



\\0 \ k\,
-
40l N.ir, & ,",
.. ... __ .


WS 1&49 s UZ Ai ar O -
VICRON.S


3US3W 4W 44 4W


Fig. 40.-Curves showing the differences in length (above) and width
(below) of conidia of various Phytophthora strains when grown on
corn meal flour under uniform cultural conditions. o- --o, strain 81;
mean length 43.11- 0.17. .---., strain 8K; mean length 50.55- 0.19.
.---., strain 8L; mean length 50.04 0.19. x- x, strain 8M; mean
length 39.73- 0.24. x- -x, strain 8N; mean length 42.56 0.18. .-
strain 8P; mean length 47.75- 0.22. 1:1-1:1, strain 8Q; mean length
47.31- 0.25. o- -o, strain 81I; mean width 26.55 0.11. ---., strain
8K; mean width 32.43 0.12. .---., strain 8L; mean width 30.31
0.10. x- x, strain 8M; mean width 27.64 0.14. x---x, strain 8N;
mean width 27.58- 0.11. .- ., strain 8P; mean width 28.09- 0.11.
1:1-1:1, strain 8Q; mean width 33.01 0.15.


170 .
160 -


I I i I I I I






Bulletin 199, Coconut Bud Rot in Florida


two strains was even greater and certainly much more signifi-
cant than the difference in their length.
ON CORN MEAL FLOUR.-The longest conidia on corn meal
flour were produced by strain 8K, while the shortest ones were


1649 19.63 ZT Z5SI 21 05 D IS J 39 J8.47 41a 44.75 4789 5103 5417 5731 6045
/Y/C/? O/V
Fig. 41-Differences in diameters of chlamydospores of the various Phy-
tophthora strains when grown on corn meal flour under uniform cul-
tural conditions. o- -o, strain 8I; mean diameter 34.31 0.16. -,
strain 8K; mean diameter 41.04 0.22. --., strain 8L; mean diam-
eter 33.67 0.13. x-- x., strain 8M; mean diameter 33.39 0.19. .- .,
strain 8P; mean diameter 35.38- 0.16. 1:1- 1:1, strain 8Q; mean
diameter 36.72- 0.19.

produced by strain 8M. There was a difference of 10.82 0.36M
between the two, which on the face of it is a very significant
difference. Strain 8Q possessed the widest conidia on this cul-
ture media, while strain 81 had the narrowest, with a difference
of 6.46 0.19/ between them. Besides having the longest con-






Florida Agricultural Experiment Station


idia, strain 8K also had the largest chlamydospores. Conversely,
8M had the smallest chlamydospores as well as the shortest con-
idia. The difference in the chlamydospore size of strain SM and
8L was both actually and statistically insignificant.
An analysis of Tables VII and VIII will show that, on each
and every one of the cultural media, significant differences in
the length and width of conidia and diameter of chlamydospores
occurred between the individual strains of Phytophthora caus-
ing bud rot. On potato dextrose agar, P. palmivora from Ja-
maica, strain 8P, differed definitely from every one of the other
strains; however, on oatmeal agar it was difficult to distinguish
this strain, on the basis of conidial length, from P. faberi from
the Philippines, strain 8K. However, these two strains differed
very pronouncedly in conidial width and in chlamydospore size.
In other cases strain 8P was similar to, or practically identical
with, other strains in conidial width, yet differing significantly
from these strains either in conidial length or chlamydospore
size, or both. On neither of the other two media was there any
one strain that could always be distinguished from all the other
strains on the basis of spore size alone.

LENGTH TO WIDTH RATIO
Spore shape has been used as a means of separating Linean
species of Phytophthora and biologic forms of P. graminis.
Rosenbaum (29) points out that length to width ratios are con-
stant characters. It is obvious that this method of expression
gives a more complete picture of spore morphology, and, when
used along with other characters, is a more useful method of
comparison.
EFFECT OF SUBSTRATUM ON CONIDIAL SHAPE OF THE DIFFER-
ENT STRAINS.-Even a superficial study of figures 30-35 will
show what a striking effect cultural media has on the shape of
Phytophthora conidia. This is but normal, since on different
media, frequently, only one diameter of the conidia is affected
by the substrata; thereby changing the morphogenic processes
of the spores. The effect of the media was by no means consis-
tent, as some strains produced a greater quantity of more or
less round conidia on one media while other strains would have
more or less elongated spores on the same media, and vice versa.
CHARACTERISTIC CONIDIAL SHAPE OF THE DIFFERENT STRAINS.
-Not only could certain of the strains of Phytophthora studied







Bulletin 199, Coconut Bud Rot in Florida


130 __ __ _




_5oC-- --- --- ---



ro













CLAM, RAT/O OF LIVGT-1 70 WI17TH1

Fig. 42.-Curves showing the differences in ratio of lengths to widths of
strain 81 (above) and strain 8K (below) when grown on different cul-
ture media under uniform cultural conditions. .- ., on potato dex-
trose agar; x- -x, on oatmeal agar; o- -o, on corn meal agar;
-., on corn meal flour.
.- --., on corn meal flour.







Florida Agricultural Experiment Station


V ~t'-


I 5 1
I j 'I,5 i. i I': I :. fl'.J "^15
'.1,- ",,'7 -


Fig. 43.-Curves showing the difference in ratio of lengths to widths of
strain 8L (above) and strain 8M (below) when grown on different cul-
tural media under uniform cultural conditions. .-., potato dextrose
agar; x- -x, on oatmeal agar; o- -o, on corn meal agar; -, on
corn meal flour.


C/AU]







Bulletin 199, Coconut. Bud Rot in Florida


to -_______

90--.___
I
80 /

70

60--

50 _

40 ___

.30/

20

10____
1 -05
1.05 US 5 L 3 1.5 .45 1.55 L.65 1.75 'L85 1.95 Z.I"


CZASS RAT o70 F ZIGTH 7T W/DTH


,__ ___ 4 \5 I 54





\ '- 4- V/IT
A4 A -- ----


40 --- -- V- _
\1/ \ -V---








.--, on corn meal flour.
105 U5 LZ M 145 W^ 165 i7S 195 a^D M ZZ.




.- ,on corn meal flour.


5







Florida Agricultural Experiment Station


be differentiated on the basis of spore size differences, but also-
on the basis of the prevailing conidial shape when produced on
certain congenial media. Thus, for example, the conidia of the
strain 8P were predominately ellipsoid in shape when cultured
on oat meal agar, whereas strain 8M and 8Q had a great many
spheroidal conidia. On corn meal agar, on the other hand, it is
strains 81 and 8P that may be characterized by more or less




o ,, po.a, I 4 -
e .od w pr \dmnI


















whenea own onious meda ura io of conditiConi dia
a poato dx.t:. osen aur -x, o- -mea o or
SI I I



~ I








F im of 1.i4,:, whi le rng L ihs ot prod of -- ina8
on potato dextrose agar; x- -x, on oatmeal agar ; .---., on corn

ellipsoidal conidia, while strain 8L has rather predominately


corn meal flour have a ratio of length to width of 1.75:1-c1.77:1,
whereas old conidia have a ratio of 1.52:1-1.57:1. Conidia
from a leaf of the host has a ratio of 1.55:1 and from the host
a ratio of 1.61:1. Rosenbaum (29) gives a mean ratio for this
organism of 1.47:1, while Rekiking (28) find a ratio of 1.60:1
when the organism is grown on oatmeal agar and 1.51:1 when







Bulletin 199, Coconut Bud Rot in Florida


CLASS RATIO OF 6LNGT TO WIDTH
Fig. 46.-Differences in ratio of lengths to widths of conidia of different
strains when grown on potato dextrose agar (above) and on oatmeal
agar (below) under uniform cultural conditions. o- -o, strain 81;
.- ., strain 8K; .- -., strain 8L; x-x, strain 8M; x- --x,,
strain 8N; .- ., strain 8P; 1:1--1:1; strain 8Q.







Florida Agricultural Experiment Station


L 45 ) .4 _" : \ ,S '- II '

Fig. 47.-Differences in ratio of lengths to widths of conidia of different
strains when grown on corn meal agar (above) and on corn meal flour
(below) under uniform cultural conditions. o- -o, strain 81; -.,
strain 8K; .---., strain 8L; x- x, strain 8M; x---x, strain 8N;
.- ., strain 8P; 1:1;- -1:1; strain 8Q.


rz? C







Bulletin 199, Coconut Bud Rot in Florida


grown on potato dextrose agar and corn meal flour respectively.
Rosenbaum (29) found P. parasitica had a mean ratio of. con-
idial length to width of 1.75, but Dastur (12) found a ratio of
1.37, and Ashby (2) found a sporangial ratio of 1.32-1.40. The
present study shows that these divergencies in shape, as those
in size, are evidently influenced by substratum upon which
the organism was grown, while the difference in physiologic
specialization is in itself sufficient to account for such differ-
ences.

PATHOGENICITY OF THE VARIOUS ORGANISMS
Inoculation experiments were made in the greenhouse, using
potted plants from three to six years old. As moisture is a very
important factor in the development of the disease, the experi-
ments were conducted in two series: A, in which the soil was
kept near saturation by placing the potted plants in tubs and
by keeping the outer tub partially filled with water to regulate
the water level in the soil; B, in which the plants were watered
frequently to keep them in good growing condition. In each
series of inoculations, five plants were inoculated with each or-
ganism and eight checks were inoculated with sterile distilled
water. Two methods of inoculation were used. In the first
method the outer leaves were removed and the buds punctured
with a "seeker" or "probe" which tapered from a sharp point
to a diameter of 3/16 inch. On account of the small size of the
needle, mechanical injury was reduced to a minimum. The point
of inoculation was covered with sterile cotton and kept moist by
wetting each day with sterile distilled water.
In the second method the plants were inoculated by pouring
spores suspended in sterile water into the bud.
The incubation period varied from three to 10 weeks, that
for plants inoculated by the first method being from three to
six weeks and that for those inoculated by the second being from
four to 10 weeks. Final notes were taken 90 days after inocula-
tion. (See Table IX.) The highest percentage of plants were
killed in the wet series inoculated with a needle; the next largest
percentage in the dry series inoculated with a needle; the next
largest in the wet series inoculated by pouring the suspension of
spores into the bud, and the lowest percentage was in the dry
series inoculated in the same manner. The most common symp-
tom was spotting of the leaves. Plants inoculated by both meth-








TABLE IX.-THE RESULTS OF INOCULATING COCONUT SEEDLINGS, IN (SERIES A) SOIL KEPT NEARLY SATURATED AND IN
(SERIES B) SOIL KEPT MOIST, WITH VARIOUS STRAINS OF Phytophthora.


Strains of Phytophthoras

120 (81) -P. faberi from Florida ....--------.....--...........
120 (81) -P. faberi from Florida ..................-----....
191 (119)-P. faberi from Florida-...............------.........
119 (119)-P. faberi from Florida ..................
8K-P. faberi from Philippines .......--..........
8I-P. faberi from Florida ..........................
8L-P. palmivora from Porto Rico..............-
119-P. faberi from Florida ..........................
8K-P. faberi from Philippines ..................---
8I-P. faberi from Florida .........................--
8L-P. palmivora from Porto Rico --...........
119-P. faberi from Florida ..........................
8M-P. faberi from Jamaica ........................
8I-P. faberi from Florida ..........................
8L-P. palmivora from Porto Rico --..........
8K-P. faberi from Philippines ..................
8N-P. palmivora from India .......--.........
8X (81)-P. faberi from Florida .......................
8Q-P. terrestris from Florida ....................
8P-P. palmivora from Jamaica ................
8Q-P. terrestris from Florida ......... .....
8P-P. palmivora from Jamaica ...............
8M-P. faberi from Jamaica .......................
8M-P. faberi from Jamaica ........... .....
8N-P. palmivora from India ......................
8N-P. palmivora from India ............--.....
8Q-P. terrestris from Florida ....................
8Q-P. terrestris from Florida .......---.......
8Q-P. terrestris from Florida .....--..............
8Q-P. terrestris from Florida ..........-- .....
8N-'P. palmivora from India ......................
8N-P. palmivora from India ......................
8A (81)-P. terrestris from Florida .....---..........
8A (81) -P. terrestris from Florida ....--..........


Method of
Inoculation
Sprayed
Punctured
Sprayed
Punctured
Punctured
Punctured
Punctured
Punctured
Sprayed
Sprayed
Sprayed
Sprayed
Punctured
Punctured
Punctured
Punctured
Punctured
Punctured
Punctured
Punctured
Sprayed
Sprayed
Sprayed
Punctured
Punctured
Sprayed
Sprayed
Punctured
Punctured
Sprayed
Punctured
Sprayed
Punctured
Sprayed


Series A I Series B
No. No. No. No. No. No. 1 No. I No.
Plants Killed Spott'd He'thy Plants Killed Spott'd He'thy
-...... ---..... ........................ 6 5 1 1 2 1 2
............ ........................ ........... 5 2 3 0
..... ....... .... ... ...... ........... 5 0 2 3
------- -...........----- -5 1 4 0
5 5 ............ ...................... ............ ............
5 4 1 ............ ............ ............ ............ ............
................... .................... 5 3 2 ............
.... 5 2 3
..... 5 2 1 3
----............ ................. ..... 5 1 2 2
.- .... ... ..... ........................ 5 0 3 2
.....-......... ................-- ........ 5 1 1 3
5 5 .... .. ......... ............ ............ ............
5 4 1 .................... ----- ----- .. ..
............ .. ......................... 5 2 2 1
-..-.. --....................... -- 5 3 2 0
............ ..... ........... ............ 5 2 2 1
............ ---- ...-- .............. 5 4 1 0
......-.. .-..-- ......- ............ 5 3 2 0
- -.... --. --..... ....................... 5 3 2 0
5 2 1 2 5 1 1 3
5 3 1 2 5 1 1 3
............ ............ ............ ............ 5 0 2 3
---...---..- ----.. [.----.-- .....- 5 3 2 0
........... .......... ........... ............ 5 2 3 0
.-..---.-- ---- ..... ......... ............ 5 0 3 2
5 0 1 4 ............ ............ ............ .....
............ ....... ...... ............... 5 3 2 0
5 5 ....................... .. ............ ............ ............
...................... ......... ............ 5 1 2 2
.. .... .................................... 5 3 2 0
......... ........... ........................ 5 .. ....... 3 2
.-.....- ........................ ............ 5 1 3 1
- .. ............ ....... ............ 5 0 2 3







Bulletin 199, Coconut Bud Rot in Florida


ods developed this symptom, but it was more common in the
plants inoculated by the second method.
Sixty percent of the spotted plants in series A died, while only
17 percent of those in series B succumbed. It is quite likely that
still more of the plants would have died if they had been kept
under observation longer.
It is evident from these experiments that moisture favors
the development of the disease and that puncturing the bud also
is conducive both to a more rapid development of the disease
and to a more serious final result.
The original organism with which the plant had been inocu-
lated was recovered from plants showing the early symptoms,
in each series inoculated. In many cases pure cultures were ob-
tained on plating out. In no case was it impossible to recover
the original organism.
It was perfectly evident from the results of the inoculations
that there were no essential differences in the pathogenicity of
the various Phytophthoras used. This together with the results
of the physiological and morphological studies, forces one to the
conclusion that there is insufficient justification for consider-
ing P. faberi, P. palmivora and P. terrestris as separate species,
even with the absence of the oospores.

LIFE HISTORY OF THE CAUSAL ORGANISM
SOURCE OF INOCULUM
Conidia are seldom found on specimens collected in the field,
but are often produced on specimens incubated in moist cham-
bers in the laboratory if the specimen is not overrun with other
fungi and bacteria. Conidia are found on the leaf spots rarely,
but they may be produced here also, if the specimen is placed
in a moist chamber. On specimens collected in flooded fields,
or soon after or during a series of rains, the conidia are abun-
dant on the leaves and on the unfolded leaf of the bud. Moisture
is a prerequisite for the development of spores. Clearly, there-
fore, there is an abundant source of inoculum.
Chlamydospores are frequently found in the mycelial felt on
fleshy specimens, as well as in the diseased tissues, with the ex-
ception of leaf spotted tissue, where they are rare. Chlamydo-
spores retain their vitality for a long time, as it has been found
that the organism could be isolated from a diseased specimen
held in the greenhouse for nine months after it had been killed






Florida Agricultural Experzment Station


by the organism, or for 10 months after it had been inoculated.
It is evident that the conidia which are produced in moist
weather may be a source of infective material. Chlamydospores
formed in decaying bud rotted plants left in the field may also
serve as inoculum. It is also possible that the organism may
live in old plant parts left in the soil. Sherbakoff (32) has
shown this to be the case with P. terrestris, which attacks to-
mato.
DISSEMINATION OF THE FUNGUS
Evidence from field observations indicates that the spores are
carried by the wind, wind blown rain, and water. Wind un-
doubtedly aids in the distribution of the spores of this Phytoph-
thora as well as those of other species of the same genus. Wes-
ton (40) has clearly shown the role that wind and wind blown
rain play in the dispersal of the spores of the Philippine Sclero-
spores, while Butler (8) has shown that wind and wind blown
rain spread P. palmivora in the Palmyra palm. Coleman (10),
Tucker (26), Ashby (2), Reinking (28) and others have pointed
out similar cases of Phytophthora spread.
There are a number of coconut nurseries in the peat soils
along the inland waterways in southeastern Florida, between
Palm Beach and Miami. In one of these nurseries at Palm
Beach many specimens of diseased palms were removed at vari-
ous times, and it was not more than six months from the date
of the first finding until bud rotted palms had been collected
from every nursery south of Palm Beach along this waterway.
It so happens that this canal frequently floods these nurseries
and thus offers one explanation as to the dissemination of this
Phytophthora. There is no doubt that water carries the spores
to the bud from the leaf surfaces where they have lodged. A
palm plant is constructed in such a manner that the upright
leaves conduct water falling on them to the crown of the plant.
Diseased nursery stock is also instrumental in spreading the
disease and it was not unusual to trace the source of an infec-
tion to diseased stock.
Cultivation of the plants plays a minor role in the spread of
the disease, as this practice is followed only during dry weather.
Dipterous insects may play a role in spreading the pathogene,
as a little scavenger fly and its larvae are found constantly
associated with the diseased plants. Leach (19a) has found a
species of this insect to be not only a carrier of the potato black-







Bulletin 199, Coconut Bud Rot in Florida


leg organism, but an agent of inoculation as well. Borers, cock-
roaches and other insects are found in or on the plants, but the
little scavenger fly seems to be more definitely incriminated.

LONGEVITY OF SPORES
Chlamydospores, sporangia, and zoospores retain their viabil-
ity only a very short time if they are permitted to dry. The
life of any of the spore forms is prolonged if they are kept under
slightly moist conditions. Temperature also may be a factor,
as it has been noted that cultures left at room temperature
(22-260C.) from two to three months lose their viability. Cul-
tures held at 16-180C. in the ice box for the above period retain
their vitality. Chlamydospores germinate readily and even an
occasional sporangia germinates. In case zoospores do not
germinate in a few hours after forming, it seems that their
power to germinate is lost. Undoubtedly the chlamydospores are
the most important in enabling the organism to persist through
adverse conditions. They have been found to retain their vital-
ity in agar culture for more than a year, and in bud rotted speci-
mens held in moist conditions in the greenhouse for more than
nine months.
SPORE GERMINATION
CONIDIA
Conidia are potential zoosporangia, and consequently may
germinate by the production of one or more germ tubes or by
the production of zoospores. The manner of germination seems
to depend upon certain environmental conditions which have
not yet been definitely determined. If the conidia are placed in
culture media, they send out from one to six germ tubes. In
case one or two germ tubes are formed, these appear near the
papilla, and, in case more are formed, they appear at-any point
on the spore. Frequently a primary conidium may give rise to
a secondary conidium, a secondary conidium to a tertiary con-
idium, etc., until the organism exhausts itself. Each of these suc-
ceeding spores becomes smaller and smaller; but yet, like the
original spores, each may act as a sporangium. Occasionally a
conidium gives rise to a chlamydospore-like body which germi-
nates by zoospores. In this case a zoospore may germinate in
situ or escape through a rupture in the spore wall. (See Fig. 48.)







Florida Agricultural Experiment Station


- ,- ,-.Z .. i, '. .
* -, ^'


Fig. 48.-Types of spore germination. A. Chlamydospores by direct germi-
nation, conidia by direct germination, zoosporangia by zoospore forma-
tion (x 500). B. Showing successive steps in zoospore formation, lib-
eration and germination of zoospores (x 750).


IT,







Bulletin 199, Coconut Bud Rot in Florida


In the case of zoospore formation, from five to 30 zoospores
may be produced. The size of the sporangium is the limiting fac-
tor, as the zoospores are from 7k to 11, in size. They are formed
as irregular bodies within the sporangium, and sometimes they
do not round up until they are liberated. In other cases they
may be formed as irregular bodies within the sporangium, where
they round up and take on the general appearance of a bunch of
grapes. Before they are liberated from the sporangium an ag-
gregation takes place. Then the zoospores move rapidly around
the walls of the sporangium, all moving in the same direction.
During this process the papilla dissolves and the zoospores es-
cape by means of a considerable elongation of themselves. The
rotary movement continues until all the zoospores are free or
settle down within the sporangium. Once a zoospore escapes
from the sporangium, it remains motionless for a few seconds
at the mouth of the papilla. Sometimes a number of these spores
cluster together before they swim away. The zoospore then be-
comes reniform, is greenish in color, contains one or more vacu-
oles and the cilia appear on the ventral side. By means of these
cilia the zoospores swim rapidly, at first in a zigzag course, but
gradually they become motionless and round up. If the spore
hits an object in the course of its travel, it bounces off and then
goes forward or retraces its original path. After coming to
rest the zoospore germinates within two hours by sending out
a germ tube. Zoospores which are not liberated from the spor-
angium may germinate in situ and send the germ tubes through
the sporangial wall.
Butler (8) found that Phytophthora (Pythium) palmivora
liberates its zoospore mass into a bladder, or prosporangium, in
which the zoospores are differentiated while in other cases the
zoospores are liberated directly from the sporangium. Dastur
(12) finds that a prosporangium is formed in the case of P.
parasitica, and Rosenbaum (29) reports this bladder-like body
in the case of P. cactorum, P. omnivora (P. arecae) and P. para-
sitica. Ashby (2) failed to note this method of zoospore libera-
tion in his studies of P. palmivora in Jamaica, while Reinking
(28) and Gadd (15 and 16) observed direct liberation of the
zoospore from sporangia of P. faberi.
In making a study of spore germination, it has been found
that young spores germinate by zoospore formation more rap-
idly than old spores. The highest percentage of zoospore forma-






Florida Agricultural Experiment Station


tion was noted in water condensed on the walls of a test tube
in which a culture of strain 8L was growing on lima bean agar
at a temperature of 27C. (Fig. 49.)


\.


.7 .

a' $F


-c4s


I,


r ~

ti:


Fig. 49.-Zoospore production showing various stages of development and
germination. A. Sporangia about to liberate zoospores (x 500). B.
Numerous zoospores and empty sporangia (x 90). C. Zoospores ger-
m nat ne in place within a sporangia (x 500). D. Zoospores germinat-
ing (x 90).


. .1






Bulletin 199, Coconut Bud Rot in Florida


Spores placed in distilled water germinated very poorly re-
gardless of age or the treatment. Placing spores in tap water,
rain water, water collected from the host, or water in which a
little host tissue had been added, is conducive to a high percent-
age of conidia germinating as zoosporangia. This is especially
true for strains 8L and 8K, when chilled in the icebox in a water
suspension containing macerated host tissues, where as many as
80 percent of the spores germinated as sporangia. Zoospore for-
mation could be noted after 15 minutes of chilling and would
continue for approximately two hours. The remaining ungermi-
nated spores would then act as true conidia and germinate by
germ tube formation.
Ward (39) considered that the liberation of zoospores was
favored by the presence of free oxygen. Melhus (24) concluded
that there was sufficient oxygen in the conidium of Phytoph-
thora infestans to permit germination without the presence of
free oxygen in water. He also concluded that temperatures be-
tween 11-200C. are conducive to zoospore formation. Coleman
(10) thought that light was essential for formation of zoospores
by P. omnivora var. arecae. Gadd (16) showed that light, aera-
tion of water and temperature are all important for zoospore
formation in P. parasitica and P. omnivora var. arecae but
light is unessential in the case of P. faberi. Reinking (28)
found zoospore formation in sporangia that had been freshly
formed on old cultures. Tucker (36) noted only an occasional
empty zoosporangium and states that the spores germinate pri-
marily by germ tube formation. Uppal (38) concludes that direct
and indirect germination are two different phenomena, the
former being a type of growth, while the latter is a mere break-
ing up of the protoplasm into independent units. He also finds
that under proper temperature conditions neither air nor oxygen
are essential for zoospore formation.

CHLAMYDOSPORES
Chlamydospores will germinate readily within 12 to 24 hours
in water or in culture media. They usually produce several germ
tubes, which may appear at any point on the spore. Chlamydo-
spores have not been found to produce conidia upon germination
nor to germinate as sporangia, yet chlamydospore-like bodies
produced from sporangia have been seen to germinate as spor-






Florida Agricultural Experiment Station


angia. Chlamydospores frequently become vacuolate and appar-
ently break up into large granules which look like zoospores, but
which have not been definitely identified as such.

METHOD OF INFECTION
By just what method the organism enters the host has not
been satisfactorily proven. Lateral penetration of the bud tis-
sues has been proven to take place in inoculation experiments,
and, from the symptoms of the disease, this method appears to
be the more common type. Vertical penetration may occur ac-
cording to field observations. Specimens have been collected
that show no signs of leaf spotting or leaf blighting to indicate
lateral penetration. In the inoculation experiments conducted
in the greenhouse this method was employed without success.
Repeated experiments have been made to determine whether
the organism entered the host through stomata or directly
through the epidermis, but the results were inconclusive. Cole-
man (10) states that germinating zoospores form a type of ap-
presorium at the end of the germ tube which enters the host
through the stomata.
There is direct and observational evidence that the pathogene
penetrates the sheathes of the older leaves and then pushes its
way into the younger tissues. The organism may also get into
the bud from above by spores lodging in the funnel-like area
formed by the sheathes of the older leaves around the bud.
Usually this sheath funnel is partly filled with water, in which
the spores germinate. The organism attacks the young leaf,
producing lesions which later appear as a series of spots across
the pinnae of the leaf. (See Fig. 50.) Frequently the organism
finds its way to the primordal bud tissues, which it rapidly
destroys.
PATHOLOGICAL ANATOMY
The mycelium is always inter-cellular. It never has been ob-
served to penetrate into the cells but sends finger-like haustoria
into them. The mycelium ramifies, in the inter-cellular. spaces
and grows much more rapidly in a vertical direction than lat-
erally. The generative tissues seem to be the most susceptible
and are destroyed very rapidly. The mycelium extends vertically
in both directions, but it does not progress far downward be-




































Fig. 50.-Three-year-old plants inoculated and held
in inoculated plants. B. Bud


in greenhouse. A. Shows a type of leaf injury noted
of plant completely destroyed.






Florida Agricultural Experiment Station


cause it soon reaches mature tissues which retard its growth.
The mycelium grows rapidly upward until it has reached the
level of the water retained in the bud and then the rate of
growth becomes slower. The hyphae may grow upward from
six to 18 inches, depending upon the size of the host plant and
upon the succulence of the tissues.
The inter-cellular spaces are ramified with mycelium, and
the middle lamella appears to be dissolved by the organism. In
advanced cases of the disease many unattached cells may be
found in a microscopic mount. These free cells are plasmolized
and are frequently destroyed by saprophytic fungi and bac-
teria. Thus, the combined action of the parasitic Phytophthora
and saprophytic organisms promptly reduces the primordal tis-
sues to a gelatinous mass.

SEASONAL DEVELOPMENT OF THE DISEASE
There is no particular time of the year during which the dis-
ease is most prevalent. Temperature is not a limiting factor
in the development of the disease in Florida, as the optimum
temperature for the organism is near the daily mean tempera-
ture for Florida.
It also happens that the organism has a lower minimum and
higher maximum for growth than the daily minimum or daily
maximum temperature for any given period of the year. Mois-
ture apparently is the all important factor, as the disease is
more prevalent in the lowest peat soils and in the crowded nur-
sery plantings where moisture is most abundant. Invariably,
sporadic outbreaks of the disease occur within a few months
after rainy periods. (See Fig. 51.)
The exceptionally large number of findings in the months of
March, April and May, in 1925, is due to the fact that the first
survey of the infested area was being made, as well as to the
very heavy precipitation of approximately 25 inches during
October, 1924. There is a very definite correlation shown be-
tween the curves giving the rainfall and the bud rot findings
from May, 1925 to May, 1927. Butler (8) and McRae (23) have
reported similar conditions as affecting the bud rot outbreaks
in the Palmyra palm in India. Coleman (10) reports similar
conditions for outbreaks of bud rot of the Areca palm. Reinking
(27), Tucker (36), and Ashby (2) have noted seasonal influ-







Bulletin 199, Coconut Bud Rot in Florida 79

ences upon outbreaks of coconut bud rot in the Philippines,
Porto Rico, and Jamaica, respectively.
Plants growing in low peat soils have suffered heavily from
the ravages of this disease in Florida. In the vicinity of Palm
Beach, low lands that were planted to coconuts were filled in
by pumping soil from the bay. The land was flooded with mud
and water, and, under such conditions, bud rot could be found
in these plantings for months; even though the diseased plants
were destroyed as rapidly as found.






19-' --- -i - _









Fig. 51.-Curves showing the relation of rainfall and the occurrence of
bud rot, Jan. 1925-May 1927. Rainfall in inches .-- Bud rot speci-
mens x- -x.

CONTROL
In general, the methods of control used are exclusion, eradica-
tion, and protection. All importation of nuts and plants from
foreign territories for propagation is prohibited.
Local quarantines are placed on all properties when coconut
bud rot is found on them, as well as on properties within a quar-
ter-mile zone of the infected property. This quarantine is ef-
fective for six months after the last finding of the disease. Dur-
ing this time six monthly inspections are made, and, in case no
newly infected plants are found, the quarantine may be lifted.
When diseased plants are found they are immediately removed
and burned. In addition, the plants in the vicinity of an in-
fected plant are sprayed with 5-5-50 Bordeaux mixture plus a
sticker of fish oil soap.






Florida Agricultural Experiment Station


Butler will attack the coconut plant causing bud rot. Tucker
(37) finds that Sabal causarium (Cook) Beccari is also attacked
by P. palmivora. Reinking (28) has proven that P. faberi MaubL
attacks the coconut palm, and the writer has shown that P. ter-
restris Sherbak. also causes bud rot. Ashby (2) has shown that
P. parasitica causes a leaf stalk rot as well as bud rot of the
coconut. He also agrees with Dastur (12) that it is synonymous
with P. terrestris Sherbak., which, in Florida, causes a fruit rot
of the tomato and a root rot of citrus. Reinking (28) was suc-
cessful in producing fruit rots of tomato, apple, papaw, and ca-
cao; as well as a seedling blight in a number of plants with P.
faberi. Gadd (15), from a study of strains of P. faberi, isolated
from various diseased plants, concludes that the various organ-
isms may be separated into two groups, which he concludes are
biological varieties.

SUMMARY
1. Coconut bud rot, caused by a species of Phytophthora,
was found in the vicinity of Miami in January, 1924, and, since
that date, has been found in an area 140 miles along the south-
eastern coast of Florida.
2. There are some 2,250,000 coconut palms in Florida, hav-
ing a commercial value of approximately $3,000,000. To date
75,000 bud rotted plants have been destroyed.
3. The most noticeable symptoms of the bud rot are yellow-
ing, wilting, and death of the terminal bud, which eventually
falls from the plant, followed by the dying of the outer leaves.
The generative bud tissues are reduced to an odoriferous gela-
tinous mass from which numerous saprophytic organisms may
be isolated.
4. Several species of Phytophthora have been described as
the causative agents of coconut bud rot, i.e. P. palmivora Butler,
P. faberi Maubl., P. parasitica Dastur, P. terrestris Sherbak.
and P. omnivora var. arecae Colem.
5. Strains of Phytophthora isolated from bud-rotted palms
in Florida have been compared in their physiology, morphology
and pathogenicity with P. terrestris, P. faberi, and P. palmi-
vora. These latter organisms had been isolated from various
plants by several workers in different countries.
6. Differences were noted in reactions of the various organ-
isms to different temperatures and media; in quantity and char-







Bulletin 199, Coconut Bud Rot in Florida 83

acter of vegetative mycelium, as well as in the number of spores
produced.
7. All the strains studied produced conidia and chlamydo-
spores in the same manner, but in no case was the production
of oospores observed.
8. Statistical studies of spore morphology were made under
comparable conditions, the various organisms having been
grown on similar media under uniform cultural conditions. Data
were obtained on length, width and shape of conidia, and the
diameter of chlamydospores.
9. By the use of biometric constants the organisms studied
were compared when grown on the same or different media. The
organisms differed significantly from one another when grown
on the same media under uniform environmental conditions.
However, each organism varied considerably when grown on
different media. It is apparent that the variation within the
same organism grown on different media is as great as or even
greater than the variation between different organisms grown
on the same media.. Different culture media affected spore size
of the different strains differently.
10. The ratio of length to width of the conidia has been de-
termined in order to establish the composite shape of the spores.
There was great variability, both intrinsic as well as caused by
the medium upon which the organism was grown.
11. Wounded and unwounded plants were inoculated with
each organism and bud rot was readily produced. The percent-
age of successful infections was much higher in the wounded
plants. Plants grown in very moist soil succumbed more readily
to the disease. There were no distinguishable differences in the
disease symptoms produced by the different organisms.
12. The mycelium within the host tissue is inter-cellular,
ramifies in the inter-cellular spaces, and sends finger-like haus-
toria into the host cells. Very little progress is made by the
mycelium below the generative tissues into or up the bud above
where it projects from the sheath.
13. Conidia are seldom, if ever, produced on diseased plant
parts unless there is an abundance of moisture, but chlamydo-
spores are frequently found in the mycelial felt on the diseased
parts of the plant.
14. Bud-rot-producing Phytophthora spread by means of
conidia, by the aid of wind, wind-blown rain, and by water,







Florida Agricultural Experiment Station


during the rainy season. Chlamydospores, and even bits of my-
celium, are possibly carried by the same means, and even by
the scavenger flies.
15. Each conidium is a potential sporangium and may germi-
nate by means of a germ tube or by producing zoospores.
Chlamydospores germinate by the production of one or several
germ tubes.
16. Just how the pathogene gains entrance into the plant
has not been determined, but direct penetration of the organ-
ism into the bud tissues, either laterally or vertically, is probable.
17. Conidia and zoospores have a short period of life, even
under the most favorable conditions, and chlamydospores seem
to be the only means of tiding the organism over adverse con..
editions. Chlamydospores have been found to retain their vital-
ity in diseased plant parts for nine months.
18. Coconut bud rot may appear at any time of the year, but
is found more commonly a month or two after periods of heavy
rains. The disease takes its greatest toll of plants in nurseries,
particularly on low peat soils.
19. From morphological, physiological and pathological
studies of the several organisms causing coconut bud rot only
minor differences have been noted. These differences are not
sufficiently great to warrant the classification of these organ-
isms as species, but, on the other hand, they seem to be only
physiologic strains within a species. The writer, therefore,
agrees with Leonian in placing all these strains in the group
species Phytophthora omnivora DeBary.
20. Control has been effected by the use of local quarantines,
destruction of diseased plants, and the protection of the healthy
plants by the use of Bordeaux mixture and fish oil soap.

LITERATURE CITED
1. ASHBY, S. F.
Notes on diseases of cultivated crops observed in 1913-14. Coco-
nut palm. West Ind. Bul. 2:299-315. 1915.
2.
Notes on two diseases of the coconut palm in Jamaica caused by
fungi of the genus Phytophthora. West Ind. Bul. 18:16-73. 1920.
3.
Relation between cacao pod rot and coconut bud rot. Agr. News.
West Indies. (Barbados) 20:318. 1921.







Bulletin 199, Coconut Bud Rot in Florida 85

4. BABCOCK, E. B. AND CLAUSEN, R. E.
Genetics in relation to agriculture. 675 p. Pub. McGraw-Hill Book
Co. (New York, London). 1918.
5. BURGER, 0. F.
Variations in Colletotrichum gloeosporoides. Jour. Agr. Res. 20:
723-736. 1921.
6. BUTLER, E. J.
Some diseases of palm. Agr. Jour. of Ind. 1:299-310. 1906.
7.
An account of the genus Pythium and some Chytrideaceae. Mem.
Dept. Agr. Ind. (Bot. Ser.) 1:1.158. 1907.
8.
Bud rot of palms in India. Mem. Dept. Agr. India. 3:221-280. 1910.
9.
Bud rot of coconut and other palms. Rep. Proc. Imp. Bot. Conf.
London. p. 145-147. 1924.
10. COLEMAN, L. C.
Diseases of the Areca palm (Arecae catecha L.) 1. Kaleroga or
rot disease. Ann. Mycol. 8:591-626. 1910.
11. COOK, 0. F.
Origin and distribution of the cacao palm. U. S. Dept. Agr. Div.
Bot. Contributions from U. S. Nat. Herb. 7:257-293. 1901.
12. DASTUR, J. F.
Phytophthora of an Heva brasiliensis. Mem. Dept. Agr. India.
(Bot. Ser.) 8:217-232. 1916.
13. DELACROIX, G. & MAUBLANC, A.
Les maladies des plants cultivees dans les pays chauds. Maladies
du Cacayes. 1. La Pourriture brun des cabosses. Agr. Prot.
Pays Chauds. 9:314-318. 1909.
14. FABER, F. C. VON.
Die Krankheit und Parasiten des Kakaobaumes. Arbeit ans der
Kaiser. Biolog. Ans. fur Land. und Forstwirtschaft. 7:195-347.
(Die Phytophtorafaule der Kakaofruchte.) 1909.
15. GADD, C. H.
Phytophthora faberi Maubl. Ann. Roy. Bot. Gardens. Peradeniya.
9: Sec. A. Botany, p. 47-89. 1924.
16a.
The relationship between the Phytophthorae associated with the
bud rot disease of palms. Ann. Bot. 41:253-279. 1927.
16.
The swarming of zoospores of P. faberi. Ann. Bot. 38:394-397.
1924.
17. JOHNSTON, J. R.
The history and cause of the coconut bud rot. U. S. Dept. Agr. Bur.
PI. Inds. Bul. 228. 1912.







86 Florida Agricultural Experiment Station

18. LARUE, C. D. & BARTLETT, H. H.
Demonstration of numerous distinct strains within a normal species
Pestalozzia guepini Desm. Amer. Jour. Bot. 9:79-92. 1922.
19. LEACH, J. G.
The parasitism of Colletotrichum lindemuthianum (Sacc. & Magn.)
(Bri. & Cav.). Minn. Agr. Exp. Sta. Tech. Bul. 14:1-41. 1923.
19a.
The relation of the seed corn maggot (Phorbia fusciceps LeH.) to
the spread and development of potato blackleg in Minnesota.
Phytopath. 16:149-175. 1926.
20. LEONIAN, L. H.
Physiological studies on the genus Phytophthora. Amer. Jour. Bot.
12:444-498. 1925.
21.
Effects of different hosts union the snorangia of some Phytoph-
thoras. Phytopath. 17:483-490. 1927.
22. LEVINE, M. N.
A statistical study of the comparative morpho'ogy of biologic forms
of Puccinia graminis. Jour. Agr. Res. 24:537-567. 1923.
23. MCRAE, W.
Inoculation experiments with Phytophthora palmivora Butl. on
Borassus flabellifer Linn., and Cocos nucifera. Mem. Dept. Agr.
India. (Bot. Ser.) 12:57-70. 1923.
24. MELHUS, I. E.
Germination and infection with the fungus of late blight of pota-
toes. (Phytophthora infestans). Wisc. Agr. Exp. Sta. Res. Bul.
37:1-64. 1915.
25. RIETZ, H. L. AND SMITH, L. H.
On the measurements of correlation with special reference to some
characters of Indian corn. Ill. Agr. Exp. Sta. Bul. 148:291-316.
1910.
26. REINKING, 0. A.
Philippine economic plant diseases. Philippine Jour. Sci. 13: Sec. A.
p. 165-216, 217-274. 1918.
27.
Phytophthora faberi Maubl.: The cause of coconut bud rot in the
Philippines. Philippine Jour. Sci. 14:131-151. 1919.
28.
Comparative study of Phytophthora faberi on coconut and cacao
in the Philippine Islands. Jour. Agr. Res. 25:267-284. 1923.
29. ROSENBAUM, J.
Study of the genus Phytophthora. Jour. Agr. Res. 8:233-276. 1917.
30. SHARPLES, A. AND LAMBOURNE, R.
Observations in Malaya on bud rot of coconut. Ann. Bot. 36:55-70.
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31. SHAW, J. F. AND SUNDARARAMAN, S.
Bud rot of coconut palms in Malabar. Ann. Mycol. 7:251-262. 1914.







Bulletin 199, Coconut Bud Rot in Florida 87

32. SHERBAKOFF, C. D.
Buckeye rot of tomato fruit. Phytopath. 7:119-129. 1917.
:33. STAKMAN, E. C. AND LEVINE, M. N.
Effect of certain ecological factors on the morphology of the
urediniospores of Puccinia graminis. Jour. Agr. Res. 5:43-77.
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:34. SYDOW, C. AND BUTLER, E. J.
Fungi Indiae Orientalis. Ann. Mycol. 5:512. 1907.
:35. SUNDARARAMAN, S.
Bud rot of coconut caused by Phytophthora palmivora. Agr. Jour.
Ind. 19:84-85. 1924.
36. TUCKER, C. M.
Phytophthora bud rot of coconut palm in Porto Rico. Jour. Agr.
Res. 34:471-498. 1926.
.37.
Sabal causiarum (Cook) Beccari.: A new host of the coconut bud
rot fungus. Jour. Agr. Res. 34:879-888. 1927.
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Relation of oxygen to spore germination in some species of Per-
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