• TABLE OF CONTENTS
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 Title Page
 Frontispiece
 The papaya
 Papaya culture
 The fruitful papaya
 Index














Group Title: Bulletin. New series no. 90
Title: The papaya
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00089083/00001
 Material Information
Title: The papaya a fruit suitable for south Florida
Series Title: Bulletin. New series no. 90
Physical Description: 60 p. : ill. ; 23 cm.
Language: English
Creator: Stambaugh, Scott U
Florida -- Dept. of Agriculture
Publisher: State of Florida, Dept. of Agriculture
Place of Publication: Tallahassee Fla
Publication Date: 1937?
 Subjects
Subject: Papaya -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Scott U. Stambaugh.
General Note: Cover title.
General Note: Includes index.
 Record Information
Bibliographic ID: UF00089083
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AMG3654
oclc - 41560664
alephbibnum - 002458305

Table of Contents
    Title Page
        Page 1
    Frontispiece
        Page 2
    The papaya
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
    Papaya culture
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
    The fruitful papaya
        Page 55
        Page 56
        Page 57
        Page 58
    Index
        Page 59
        Page 60
Full Text








The Papaya


..m Fruit Suitable for
Soutk Florida


SCOTT LI.


By
STAMBAUALGH


X




































-1j~j<;


Field run of Blue-Solo variety, fourth hybrid generation. These fruits are from perfect flowered seedlings
only. The tendency to uniformity apparent in size and shape as indicated by the picture carries through all other
fruit characters.













1he Papaya
A Fruit Suitable For South Florida

The papaya is a giant soft stemmed annual bearing plant.
This point is stressed at the beginning as it is of paramount
importance in the culture and breeding of the papaya. The
papaya grower or breeder should understand that he is
dealing with a quick growing truck crop and make his plans
accordingly all down the line. The papaya is not in any
sense a tree and cannot be treated as a tree crop. It is true
that under ideal conditions the papaya will live and produce
fruit for seven or eight years. This fact together with its
appearance have resulted in a general misunderstanding.
Growers will treat the papaya as they would treat their
tree crops. More papaya failures have resulted from this
plan than all other factors put together. The papaya grower
should treat his papaya crop in the matter of general care in
exactly the same manner as if, for instance, he were growing
three crops of tomatoes on the same piece of land one right
after the other. The only difference is that with the papaya
he would only plant once.

In appearance the papaya plant is sometimes compared
to the palm. There is a single tall fleshy stem that may be
anywhere from six feet to a maximum of thirty-five feet
tall. At the top of this stem there is a single bud. This bud
is the growing terminal and does all the work for the plant.
Around the top of the bud radiates a crown of large leaves
on long stems. All blossoms appear directly on the main
stem of the plant at the base of leaf. All fruit appears at-
tached directly to the main stem of the plant by short stiff
fruit stems.
The fruit itself is melon like in appearance and is best
described as the cantaloupe that grows on a tree. The fruits
vary tremendously in all characters under natural con-
ditions. They may be almost any size from that of a walnut
to twenty-eight pounds. The shapes run from almost per-
fectly spherical through eggshape, through pearshape or
even almost perfectly cylindrical. The flesh is like that of a








4 DEPARTMENT OF AGRICULTURE

melon and may be anything from a quarter of an inch thick
to fully two inches. The flavor and texture may be anything
from that of a fine cantaloupe to the actively unpleasant
musky odor and flavor of the wild fruit. The seeds appear
inside of the fruit attached to a fibrous aril.

The papaya is one of those fruits that first came to the
attention of white man with the discovery and conquest of
the new world. There is considerable evidence that this
fruit existed in cultivated form centuries before the white
man came. The Aztecs and Mayas of Mexico and the Incas
of the coastal country of Peru have left rock carvings of
the papaya that go back many centuries before the white
man.

The papaya probably originated in Northern Central
America or even in Southern Mexico. By the time the white
man reached the new world, however, the primitive or wild
papaya existed all over Florida, the West Indian Area,
Northern South America, Central America, and the coastal
parts of at least two-thirds of Mexico.

This primitive or wild papaya is a vigorous rapid grower
tolerant of a very wide variety of climatic and soil condi-
tions. It is possible that this type may have existed over a
lot of the territory where the white man found it as an
escape that had been carried about in the form of better
sorts by the Indians and then had reverted and gone wild.
There is an astonishing uniformity of character among the
wild sorts over this whole area. There is by the same token
a tremendous diversity particularly of fruit character on
the part of the larger fruited sorts found in the hands of
the natives of this area.

Within a hundred years after the conquest the papaya
had been distributed over practically the entire tropical
belt of the globe. It is now and has been for the better part
of two centuries a common dooryard plant almost anywhere
in the world where the climate is mild enough for its
growth.

The most astonishing thing about the papaya is that it
has remained a dooryard plant for so long a time. It has be-









THE PAPAYA-A FRUIT 5


come very important to the people who were geographically
so located that they can grow it. It has on the other hand
not been subjected anywhere to any very long time effort
in the way of fruit character stabilization and improvement.
Almost anywhere in the tropical parts of the world the
native family will have from five to fifty papaya plants in
the dooryard. They may carry a few fruits to market along
with other products, but they almost never make any effort
to commercialize the growing of papaya or improve the
character of the fruit.
In the United States and particularly in South Florida
during the past thirty-five years more ordered work has
been done with the breeding of the papaya and more effort
has been made to commercialize this fruit than in all of
the rest of the world in all of the time this fruit has been
known. The United States Department of Agriculture has
during the past thirty-five years introduced something like
150 more or less distinct varietal forms of the species carica
papaya to Florida. These varietal forms have come from all
parts of the world. This multiplicity of introductions have
hybridized at will with each other and with the undesirable
wild form. Literally thousands of fractionally hybridized
sorts practically all of which have been contaminated with
wild blood now exist in Florida. This situation has resulted
in chaos both as regards plant and fruit characters and with
regard to ideas of papaya growers.
During the last ten years some little order has gradually
been emerging out of this multiplicity of papaya types and
confusion of grower ideas. A vast lot of entirely useless
material has been so labeled and discarded. The growers
have by way of reactions of the buying public gradually
built up a mental picture of what the commercial papaya
should be and this picture is slowly being fitted to the
known facts governing the breeding of the papaya. There
is still a great deal to be done in the matter of breeding
papaya but the point has been arrived at where it is feasible
to commercialize this fruit both as a fresh fruit and for
products.
BOTANICAL CLASSIFICATION
The fruit we call the papaya has generally been classified
in all of its varietal forms under the single species carica








DEPARTMENT OF AGRICULTURE


papaya. More or less distinct varietal forms of the papaya
were found originally in every geographical division of its
original habitat and in the 400 years since the conquest
many other varietal forms have appeared in those parts of
the world to which it was introduced. Any geographical
division that tended to isolate the papaya growing in a given
territory resulted in the development of a specific varietal
form depending on climate, soil conditions, and the ideas of
the natives in whose hands they happened to be. These
varietal forms, however, were not very distinctly separated,
nor were they very stable in any territory where the wild
form existed naturally or where the wild form could estab-
lish itself as a matter of escape. The mere presence of the
wild form growing naturally in a given territory results in a
constant tendency to reversion to that form on the part of
improved sorts due to the vast quantity of wild pollen
carried by insects.

The varietal forms of carica papaya fall naturally into
two great groups according to their sex character. One
group is typically unisexual, that is, the sexes occur on
separate plants and this group is universally distributed all
over the original habitat of the papaya, that is, Florida, the
West Indian Area, Northern South America, Central
America and Mexico.
The second group that is typically hermaphroditic in
character occurs naturally only in the specific territory from
Guadalajara through Southern Mexico through Central
America into Colombia. This second group of naturally
occurring papaya varietal forms are different from the first
group in that they are much more distinct and sharply
marked in their characters than those of the first group.
The Mendelian behavior of these perfect flowered papaya
under natural conditions and under enforced self-polleniza-
tion, selection and breeding has been such as to give an
indication that they may be ancient hybrids between carica
papaya and some other carica. This other carica has either
disappeared entirely or is inconspicuous as it is at the
moment unknown and exists only as a matter of pure
theory. It is only on the supposition that such a type exists
that the explanation of the Mendelian behavior of the
perfect flowered papaya is possible.








THE PAPAYA-A FRUIT


The wild papaya as a matter of sex type is always uni-
sexual. There occurs among them what is often called the
bearing male plant, more properly the Core Type. This
Core Type is a borderline sex manifestation. It occurs not
only among the wild but among all domestic types of uni-
sexual character. The Core Type should in no way be con-
fused with the type hermaphrodite strains of papaya. The
Core Type throws an occasional hermaphrodite flower
among many thousands of male flowers on extremely long
drooping stems. These hermaphrodite flowers result in fruit,
sometimes forty or fifty of them on a single plant. The type
has no capacity for perpetuating itself through successive
generations. Seeds saved from such fruits give seedlings
that revert immediately to the unisexual type. The occur-
rence of the Core type then is purely fortuitous. Because
some of its flowers are hermaphroditic in character, the dia
has grown up that hermaphroditism in the species carica
papaya is a fortuitous character. This is an entirely errone-
ous notion. The Core type is of no Mendelian significance
any more than the occurrence of borderline sex manifesta-
tions in animals.

On the other hand the character of true hermaphroditism
in the papaya shows no tendency to occur fortuitously
among varietal forms of wild or domestic papaya that are
unisexual as a matter of type. The unisexual strains do,
however, hybridize readily with the hermaphroditic strains
and will transmit their characters other than sex in direct
line in varying combinations to hermaphroditic progeny
that can in turn be kept in line for the new characters by
selection and enforced close fertilization. An occasional
hermaphrodite seedling in recently hybridized groups with
an unisexual variety will turn out to be self sterile and
seedless when subjected to close fertilization.

OTHER CARICAS
Some little experimental work has been done in Florida
with several other species of the genus carica. Up to the
moment this work has come to nothing. These other caricas
are generally grouped under the classification Mountain
papaya as they show little or no capacity for growing or
fruiting below 4000 foot elevation. For that reason they








8 DEPARTMENT OF AGRICULTURE

have failed under Florida conditions. Then too the Moun-
tain papaya are radically different in general character from
carica papaya although members of the same genus. They
are mostly perennials requiring four years to come into
bearing and surviving for as much as twenty years. The
only known hybrid, called carica pentagon, a mule that
produces no seed except in the presence of pollen from
males of carica papaya, has been grown from cuttings in
Colombia since before the conquest of the new world.

BREEDING
The development of a stable papaya industry, if any, will
always be dependent on the annual production of a large
crop of true to type seedlings.
A sexual propagation in the papaya is of no service in the
matter of carrying on the type. Budding, grafting and even
the rooting of cuttings can be done but in the second bud
generation degeneration sets in so badly because of the
inherent lack of capacity of the annual papaya to carry on
without going through the seed in every generation as to
render this type of propagation useless. The matter of
asexual propagation is useful in the papaya only to expand
the characters of a single unusually fine desirable plant over
a number of individuals so that a large amount of seed of
that character can be produced. Beyond that point, that is,
anything but the first bud generation seems to be entirely
useless with any of the species of carica papaya regardless
of origin or sex peculiarities.
This difficulty with budding, grafting and propagation by
cuttings does not apply to the other members of the genus
carica, as it is done with carica pentagon. This is of course
another reason for regarding with a certain amount of
seriousness the possibilities of hybrids between carica
papaya and other caricas.
It would seem that this matter of papaya breeding can
hardly be regarded too seriously at this time. All the pos-
sible information that can be had in the way of scientific
facts will not be too much. This is particularly true be-
cause a lot of unfortunate confusion has arisen as to the
main basic facts of papaya breeding. This has been largely








THE PAPAYA-A FRUIT


a result of the erratic behavior of the thousands of fractional
hybrids that have occurred in Florida. The average grower
of course is absolutely helpless in this matter. Unfortu-
nately technicians have been in the past and still are to a
certain extent in disagreement on this subject.
BREEDING PROBLEMS OF UNISEXUAL
PHASES OF PAPAYA
The vast majority of the papaya growing at the moment
in Florida are not the result of breeding efforts of any
ordered character but are the results of efforts on the part
of the growers to get plants and fruits of uniform com-
mercial character by the simple process of selection. When
one considers the vast hodgepodge of original varietal forms
and their hybrids existing in Florida, it is evident that this
is a hopeless task. It may be said that at the moment there
is no such thing in Florida as a generally grown commer-
cially useful type of papaya.
This matter of simple selection for fruit and plant char-
acters under Florida conditions seems to and up to the
moment has presented insurmountable difficulties to
technician and non-technician alike.
The first great difficulty encountered in this method is
with pollen distribution. All of the papaya possible terri-
tory in Florida is infested with wild male plants and
peppered with hundreds of irregular males of domestic
origin. The result of this situation is that a female papaya
plant in any part of the territory may be receiving pollen
from dozens of sources and each individual source capable
of transmitting literally hundreds of character arrange-
ments. It is a practical impossibility to select a site for
papaya seed growing that will not be subjected to a flood of
undesirable pollen both wild and domestic. It does not
seem very likely that any uniformity of plant or fruit char-
acters can be arrived at by selecting among papaya of
unisexual character.
Another factor contributes to the difficulty of selection
among unisexuals. The Sphinx Moth group are probably
the sole pollenizing insect agent of the papaya. This insect
will be identified by the layman from having seen it around
beds of petunias and four-o'clocks in the evening. These
moths are large and strong fliers, capable of traveling many








10 DEPARTMENT OF AGRICULTURE

miles in an evening. They can and do carry both wild and
domestic pollen from over a wide territory to any given
female plant. It does not of course make a great deal of
difference whether pollen comes from a wild plant or a
domestic, plant just so long as it comes from a plant
different in ancestry than your own. Confusion of characters
results.
Now this may be regarded as more or less definitely a
Florida problem. There are thousands of places in the tropi-
cal world where the wild papaya does not exist. To most
of these locations a single introduction of papaya seed was
made some time after the Spanish conquest and that ended
the matter. In such places varietal forms of carica papaya of
unisexual character are quite uniform as to plant and fruit
characters. They have been isolated for centuries and have
resulted from only one introduction of papaya seed. It is
the multiplicity of sources of seed coupled with the distribu-
tion of the wild form that has made our difficulty.
Many of these varietal forms are useful under Florida
conditions for breeding purposes in the first generation in
Florida. They have certain definite plant and fruit char-
acters and are usually quite homozygous for those char-
acters. It should be remembered however that regardless of
how uniform they are, if they are unisexual, that is, requir-
ing pollen from another plant, they will unless protected
cross out to pollen from a thousand undesirable sources in
the first generation. Rapid and complete degeneration of
the type is inevitable.
The matter of ordered breeding work among papaya of
unisexual character does not present a much more attrac-
tive picture. It is possible of course to protect the flowers of
a chosen female plant from outside pollen by putting paper
bags over the flowers two or three days in advance of their
opening. It is then theoretically possible to hand pollenize
these flowers from flowers of selected male plants whose
flowers have been likewise protected against pollen by
paper bags. The result of this procedure is of course that
one can know the male plant from which the pollen came.
It is a serious question, however, whether this is any great
advantage or not. There are two serious difficulties to this
method of papaya breeding.








THE PAPAYA-A FRUIT


The first difficulty is with the male plant itself and is as
a matter of fact a universal difficulty with any male plant
for this purpose. A normal male plant of carica papaya
produces no fruit. The fruiting characters it may transmit
for that reason cannot be determined.

The second problem is purely a mechanical difficulty.
The transference of pollen from one papaya flower to an-
other usually results m injury of the flower parts. Latex
exudes and the pollen is digested by the active enzyme con-
tained in the latex. No fertilization and no seed result.
Attention is called to the fact that the insect system of
pollen transference in the case of the papaya is to blow the
pollen into the flowers by a blast of air resulting from the
rapid vibration of the wings of the insect. The flower parts
are never touched.

Grant that a system of pollen transference that was
feasible might be worked out, there is still among unisexuals
the problem of gauging the characters the male plant will
transmit, at least as far as fruit is concerned. Grant further
that brother and sister matings will be resorted to, there is
still no way of gauging the fruiting characteristics of the
selected male. The mother plant from which both seed that
produced any two selected plants came had in turn to be
pollenated and there is little or no likelihood that two seeds
could be selected that were the result of pollen from the
same source. Both individuals are potentially hybrids and
even though they be brother and sister, the probability is
that they are half brother and sister and hybrids of
divergent character.
It would seem then that no sound method either of
selection or of ordered breeding work among unisexual
strains of papaya offers promise enough to be worth the
effort. The perfectly natural technical problems involved
are too great.
Efforts at ordered breeding work with the typically
hermaphroditic strains of papaya present what is at first a
confusing picture but a very different picture than that of
the unisexuals. The first thing that should be said about the
typically hermaphroditic papaya plant is this: Any single
type hermaphrodite plant of the species carica papaya can


11











































































Typical plant, Blue-Solo perfect flowered, first hybrid generation on rich
permanently moist hammock soil at Vero Beach. This illustrates the capacity
of the papaya to take advantage of the soil and climatic condition to make
a large vegetative growth. This plant is taller and thinner than it would
be under other conditions because of the surrounding trees and palms.










































































4 Specimen plant of Blue-Solo showing example of off type fruits due to
five stamen flowers. Most of the fruit in this cluster is of normal character.
Three fruits near the top of the cluster are shorter and blocker than the
rest and deeply five lobed. Such blossoms when they occur should be cut
off as buds as the fruit is always of inferior character regardless of the
character of the normal fruit of the plant. Seeds should never be used from
such a plant.
:1






























Specimen plant of Blue-Solo showing example of off type fruits due to
five stamen flowers. Most of the fruit in this cluster is of normal character.

Three fruits near the top of the cluster are shorter and blockier than the
rest and deeply five lobed. Such blossoms when they occur should be cut
off as buds as the fruit is always of inferior character regardless of the
character of the normal fruit of the plant. Seeds should never be used from
such a plant.








DEPARTMENT OF AGRICULTURE


be subjected to enforced close fertilization by putting paper
bags over the flowers two or three days in advance of their
opening. Regardless of what the fruit and plant characters
of this individual plant are, they will be transmitted in
like character from both parents as both parents are the
same individual.
Now this does not mean of course that any percentage
of true to type individual plants are going to result in the
generations immediately following, but it does mean that if
among the progeny of this plant careful selection is made
for those that resemble the original chosen parent plant and
they are in turn subjected to enforced close-fertilization the
homozygous condition will eventually be approached.
The great difficulty with these hermaphroditic strains of
papaya has been not so much that they did not transmit
uniform characters to their progeny as that they showed up
with certain peculiarities of sex behavior that confused and
discouraged the growers with these strains and many
technicians.
There is, for instance, in the beginning always a tendency
for hermaphroditic seedlings when they commence to
flower to throw only male flowers during the early part of
their development. Most of these plants eventually edge
over into the production of hermaphroditic flowers and
eventually the setting of fruit. This seems to be almost
purely an expression of the impurity of the blood of the
given strain for the character of hermaphroditism. After
several generations of selection for hermaphroditism and
close fertilization enforced by paper bags over the flowers,
seedlings commence to appear whose first flowers are her-
maphroditic and set fruit. This irregularity of flower be-
havior earned the hermaphroditic strains of papaya the
reputation of being poor bearers. Any upset towards the
steady and rapid growth of the plant such as drouth, cold,
or shortage of plant foods tended to bring the male char-
acter to the surface again and only male flowers would be
produced that set no fruit. This difficulty is entirely
eradicated by selection and enforced close fertilization.

Another very definite difficulty with hermaphroditic
strains of papaya is an irregularity of stamen arrangement








THE PAPAYA-A FRUIT


in the flowers. This results in an irregularity of fruit pro-
duction or the production of fruits of several different
shapes on the same plant. The typically hermaphroditic
flower in the case of carica papaya has ten stamens and
produces fruit that is long pearshape, long ovoid, or cylin-
drical. In the beginning of the process of adaptation of new
lots of hermaphrodites or where crosses have been made to
unisexuals a considerable percentage of plants appear that
have flowers resembling those of the female plant rather
than typical hermaphroditic flowers. These flowers have
only five stamens and either fail to produce fruits at all or
produce fruits that are not entirely closed at the blossom
end. When as often happens these five stamen flowers make
fruits that develop normally they are apt to be spherical
like the fruit of female plants rather than the typically long
shape of the hermaphrodite plants. This again is a sex
irregularity probably due to a leaning over towards female
character rather than pure hermaphroditism. It is of course
an expression again of blood that is impure for herma-
phroditism. Such plants should never be used for sources of
seed stock.
When a new varietal form of hermaphroditic papaya is
being whipped into line a good many of these variations of
sex characters are apt to appear. They of course interfere
with both the quality and the character of the crop. No
hermaphroditic strain should be depended on as a new intro-
duction to produce commercial crops of fruits. Any new
variety should be subjected to at least five generations of
enforced close fertilization and selection for fruit and plant
characters before it is considered uniform enough to be of
any service either for breeding or production of fruit. This
of course entails five years of rather expensive experimenta-
tion for each new varietal form adapted.

There is a considerable family of typically hermaphro-
ditic varietal forms of carica papaya. A discussion of their
origin and what is known of their Mendelian behavior will
throw some light on their possible application to the prob-
lems of breeding uniform strains of papaya seedlings. At
this point it should be noted that DeCandole, the French
botanist, and every other scientist that has ever expressed
himself on the papaya has offered the opinion that in the









DEPARTMENT OF AGRICULTURE


hermaphroditic strains of papaya was the only hope of
producing true to type seedlings. It should also be noted
that most of them did nothing about it or did not get by the
irregular sex peculiarities of the hermaphroditic strains be-
fore giving them up.
The geographical origin of the typically hermaphroditic
strains of papaya throws considerable light on their be-
havior. They come from a definitely circumscribed terri-
tory, commencing at Guadalajara on the North and running
down through Southern Mexico, Central America, and into
Colombia. Now both the wild unisexual strains of papaya
and the larger fruited domestic strains of unisexual papaya
exist coincidentally in the same territories. Now one thing
seems to be significant. These hermaphroditic forms do not
occur outside of this area except as the result of provable
introductions. It should be mentioned again that type
hermaphrodites do not occur fortuitously among any race
wild or domestic of the unisexual strains of papaya.
In the original habitat of the hermaphrodite strains of
papaya each isolated valley is apt to contain its own strain
of hermaphroditic papaya and that strain will be of con-
siderable uniformity as to habit of growth and fruiting
character. The Mendelian behavior of seedlings of any and
all of these varietal forms is identical regardless of their
source.
Seed taken just as it is introduced from a known herma-
phroditic source will result in seedlings that run 18% to
20% hermaphroditic and the remainder of the seedlings will
be about equally divided between male and female plants.
Now this indicates the problem. Hermaphroditism is the sex
type for the plant and yet only 20% of the seedlings are
hermaphroditic and 80% of them are unisexuals. This ap-
parently is an expression of the impurity of the blood under
natural conditions for the character of hermaphroditism.
This has its origin apparently in the fact that the flowers of
the type plant when they open in the morning are mature
as far as the male character is concerned. The pollen sacks
are ruptured and the pollen is ripe. The stigmas of these
flowers, however, are not receptive until evening of that
same day. During the day wind and insects are responsible
for most of the pollen native to the flower getting away. It








THE PAPAYA-A FRUIT


seems evident that the percentage of hermaphroditic seed-
lings expresses the degree of nature close fertilization and
the percentage of unisexual seedlings produced is an ex-
pression of the degree of cross fertilization. It is significant
that to the degree that seedlings of an hermaphroditic plant
are hermaphroditic they are fairly close as to plant and
fruit characters. It is also true that as the percentage of
hermaphroditic seedlings increases under enforced close
fertilization these added hermaphroditic seedlings are also
very close in plant and fruit characters to the parent plant.

It seems evident then that the assumption can be taken
that hermaphroditismin the papaya is a definite character
and will Mendelize. The unisexual seedlings that occur from
hermaphroditic sources are simply out crosses and must be
disregarded. It has been maintained that hermaphroditism
in the papaya was a fortuitous character. This does not seem
to be the fact. The Core type is fortuitous and does not
Mendelize. The situation is just the opposite when dealing
with the type hermaphrodite. The facts are obscured some-
what by the occurence of so many unisexual seedlings. The
facts are there nevertheless.
A new lot of seed of known hermaphroditic origin is
simply a lot of seed that will under selection give the oper-
ator a certain percentage of hermaphroditic seedlings that
are known in advance to be of very impure ancestry. As
large a group of hermaphroditic seedlings as possible grown
from seed known to have come from a single plant should
be segregated and as they grow off thoroughly studied and
classified for occurrence of plant and fruit characters. When
a plant or fruit character occurs on a majority of such plants
that plant or fruit character may be taken as accurate for
the type. In the beginning there is no probability that all of
the characters that are type for the strain under considera-
tion will appear on any one individual. If a number of the
plants that have the greatest majority of type characters are
close fertilized and their seedlings grown off and studied, a
higher percentage of the characters that are type for the
strain will occur in the individual plants. If this procedure
is resorted to for a second and third time sooner or later all
the characters that are type for the strain will appear in a
single individual. At that point the battle is half over.








18 DEPARTMENT OF AGRICULTURE

It may not be theoretically sound genetics but it has
been the practice of this operator to consider that once all
of the characters of the type appeared in a single individual
then the strain was ready for further hybridization. At
this point it is usually true that 65% or 70% of the seed-
lings will be hemaphroditic, less than 1 per cent male, and
the residue females.

This process is somewhat involved and of course neces-
sitates a close knowledge of the superficial characters of
all parent stocks involved. It has been carried out through
thirteen generations and three hybridizations in one case.
The resulting complex hybrid race is by no means homozy-
gous but has plant and fruit characters that are remarkably
uniform when compared with any other existing varietal
form and in recent generations have shown definite tend-
ency to stay in line.











Papaya Culture



The grower should never lose sight of one general
fact with regard to the growing of papaya in Florida. The
wild papaya is very probably native to something like two-
thirds of Florida. None of the improved sorts, however,
naturally belongs in Florida. They are truly tropical forms
that in being moved to Florida are being crowded out of
their natural climatic range.
For this reason the culture of papaya in Florida requires
specific attention to climatic conditions, particularly atten-
tion to the fact that Florida through part of the year is
considerably colder than the natural habitat from which
the improved sorts of papaya regardless of variety came.
This matter of the climatic necessities of the better types
of papaya is definitely a limiting factor. It results in the
papaya being adaptable only to certain specific and re-
stricted areas under Florida conditions. The site for a
papaya plantation must be picked with an eye on the
probable occurrence of frost, the depth to which the tem-
perature can fall, the number of times that it will fall below
32, and the number of hours that it will stay there. These
factors will determine the economic feasibility of using any
specific site for the growing of papaya for profit.
The papaya will be damaged by frost of any degree, and
certainly damage will occur if they are exposed to tempera-
tures of 32 or below. If the temperature in the papaya
plantation goes to 32 or below, for just so long as it
stays there some method of frost protection must be resorted
to.
There is a considerable variation among papaya varieties
as to their reaction to cold and there is a considerable vari-
ation to the effect of low temperatures on the plants and
fruits with regard to the character and moisture condition
of the soil on which they are growing. These variations are,
however, all variations of the capacity of the type or the
situation to enable these plants to resist temperatures
slightly above 32. It may be laid down as a dictum that






















































q **Ni


YI~-,r
r9 ~
--
r r- r
' ri .1 ~*I*



'

~L` c
.J 'I.i
,I
.r ...
~." .rc~


v 27'~ci


S .;


Specimen plant old type big Blue-Stem. Unisexual female, grown on scari-
fied Oolite Limestone.


`I +













































Planting of Blue-Solo at 18 months of age. Average height of plant 20 feet. Spacing 10 feet each way. This
picture illustrates the capacity of the papaya to grow and fruit when plenty of plant food is available together with
moisture, deep soil, and plenty of organic content.








DEPARTMENT OF AGRICULTURE


no papaya variety under any situation will stand tempera-
tures of 32 or below.
The papaya has been grown in protected spots from Key
West to St. Augustine and all across the peninsula in Flor-
ida. Sporadic efforts have been made to grow it all along
the Gulf Coast from Tampa to Galveston. It has been quite
successfully grown in the Rio Grande Valley of Texas. In
California it has only succeeded under glass. Now just
what parts of all this territory will in the long run be
marked out as economically suitable for the growing of
the papaya is still a problem. It should be pointed out that
this is purely an economic problem. One very successful
papaya venture has been going ahead for a number of years
in a glass house just outside of Los Angeles. This grower,
however, received 40c a pound wholesale for his crop. This
is no indication of the general fact but does indicate how
far an artificial situation can go when the price justifies it.

In gauging the climatic suitability of any given territory
for papaya, the matter of frost, its occurrence and severity
may occasionally turn out to be a secondary matter. The
growing of any crop for sale is always an economic pro-
blem rather than a purely physical one. A given territory
may have under average conditions two or three severe
frosts through which a papaya crop could be taken by the
use of heaters. The cost of this matter of the protection
of the crop with heaters may be considerable and it is still
true that if there is a good local market for papaya, it might
be economically a perfectly sound project to grow papaya
on that particular piece of land.
Another territory might have no frost at all but might
have, as some territories do in Florida, a low average sun-
shine and temperature index for the winter season. This
would prevent the ripening of the fruit of the papaya dur-
ing the winter and as this is the time of the year when it
could be sold to the greatest advantage, then this second
territory would have to be ruled out as a matter of eco-
nomics as a papaya feasible spot.
The papaya grower then should make the weather and
all factors of the weather in a given spot a study as to suit-
ability for the growing of papaya. By the same token he








THE PAPAYA-A FRUIT


should not neglect the matter of economics and a great
many factors other than weather enter into the matter of
economics.
SOIL DEMANDS
The papaya is tolerant of and if certain conditions are
met even thrives on an astonishing variety of soils. Under
Florida conditions the papaya has been grown:
In South Dade County, on land that was almost pure
Oolite limestone. Holes were blasted in the rock or the
surface was broken up with a road ripper or scarifier. The
papaya plants were then grown by applying large quanti-
ties of organic material in the form of compost, commercial
fertilizers and water. Very satisfactory crops have resulted.

On the marl soils large crops of papaya have been pro-
duced very economically on a soil that is almost pure Cal-
cium Carbonate and shows a usual pH of 8.1. Such soils,
however, are always in hazardous spots for the planting
of papaya as they are very susceptible to flooding or satura-
tion in wet periods. Either flooding or the saturation of
the soil for any period of time will completely destroy a
papaya crop.
The papaya has been grown on shallow sandy soils of the
flat pinewoods underlaid with hardpan. Where these soils
can be defended from water and frost, they seem to be en-
tirely suitable.
In the deep sandy soils of the beach ridges along the
coast, fine papaya crops can be grown with the application
of fertilizer and water. Such locations are apt, however, to
be quite susceptible to wind damage.
Papaya have been grown quite successfully in what are
usually called muck soils, more properly called peat in
places all over the State. Muck soil planting are of doubt-
ful value. The plants grow off rapidly and make tremend-
ous quantities of fruit that is apt to be of poor quality. In
addition to that muck soils are usually so located as to be
hard to protect from frost and overflow.

Papaya have been grown successfully on the deep allu-
vial soils of the Rio Grande Valley of Texas.








24 DEPARTMENT OF AGRICULTURE

As a matter of chemical character the pH condition of
all these soils covers a range from 4.5 to as high as 8.3.
There is very little evidence that the papaya reacts ad-
versely to the matter of pH alone. It is evident, however,
that this plant requires larger percentages of organic ma-
terial in the soil makeup and a greater plant food concen-
tration at the extremes of pH condition of soil than it does
at from 6.5 to 7.5. Extremes of pH then are apt to increase
the cost of growing papaya. A very low pH of course can
be corrected quite economically and easily by the applica-
tion of Dolomitic Limestone or Thomas Slag.
This range of soil characters as to organic comprises
everything from as low as 2 per cent organic to an almost
totally organic soil. The response of this crop to the appli-
cation of organic material in the form of compost on all
these different varieties of soils is tremendous. This is at
first glance a bit of a puzzle with regard to the muck soils,
but probably results from the fact that these peaty soils
are as matter of fact the result of partial anaerobic decom-
position of vegetable debris and these soils are actually
composed of preserved vegetation in a very stable and un-
available form.
The ideal papaya soil is probably a deep, loose, well
aerated, sandy soil. Such a soil is only usable, however,
when provided with plenty of organic material, plenty of
plant foods, and regular moderate applications of water.
Such a soil and cultural arrangement will result in large,
long lived plants that will produce heavy crops of fruit
of the best character for the type.

MOISTURE REQUIREMENTS
The papaya is often listed as a drouth resistant crop.
This is a statement of fact but should be qualified. The
papaya will live over for long periods on very little soil
moisture. It should be added, however, that the crop will
do little or nothing in the way of advancement during
that period. The plant will resist drouth and will stay
alive but will make little or no growth either of plant
or of fruit during the dry period. It should be borne
in mind that the eventual capacity of the papaya crop
to produce satisfactory tonnage of fruit will be very defi-








THE PAPAYA-A FRUIT 25

nitely limited by allowing the crop to be subjected to
a long drouth without irrigation. Where the texture of
the soil is such that it can, the papaya develops a truly enor-
mous root system and for that reason has the capacity,
once well established in the soil, to make use of tremendous
quantities of moisture if applied regularly and in moderate
doses.

The papaya should never be planted on soils that can
under any extreme of weather condition overflow or even
become saturated with standing water, no matter how short
the period. The demands of this crop in the way of soil
aeration are such that if air is shut out of the soil by stag-
nant water for even a 24-hour period, the result will be a
total loss of the crop. It is sometimes possible to plant lands
under forced drainage that would otherwise flood. It should
be definitely understood in planting such lands that surplus
water must be removed as it falls by the pump route. This
is purely an economic problem. Sometimes soils occur
whose location gives them unusual frost protection, whose
texture, pH, and natural plant food content is good. The
situation may be such, however, that the natural run-off of
rainwater is insufficient to take care of the extreme condi-
tion. Here again, it is largely an economic problem. It may
be worth while to install pumps to force water off of such
lands.

The matter of irrigation should be gone into with regard
to any piece of land under consideration for the growing of
papaya. The papaya is in any case a comparatively expen-
sive crop when judged from the standpoint of fixed over-
head charges per acre. The total yield of papaya on a giv-
en acre of land can usually be more than doubled by system-
atic irrigation. It is hardly worth while, therefore, to at-
tempt papaya growing commercially without irrigation.
The papaya crop, once the plants are established and grow-
ing say from the time they are 3 feet high, should have the
equivalent of an inch of rainfall each week. If that much
rain does not occur, it should be provided as irrigation. In
figuring for irrigation the grower must not lose track of
the fact that it takes approximately 26,000 gallons of water
applied to the surface of an acre to be the equivalent of an
inch of rainfall.








DEPARTMENT OF AGRICULTURE


All sorts of irrigation systems have been tried for the
growing of papaya in Florida. The overhead system of ir-
rigation with permanently installed equipment is of course
the ideal system. Such a system, however, usually costs in
the neighborhood of $450.00 for the standing equipment on
each acre, plus the cost of main pipelines and pumping
equipment. Then there is the matter of portable overhead
irrigation where a four acre unit consists of a small pump,
420 feet of main line and 210 feet of sprinkler line. The
sprinkler line is moved from station to station, set up four
times on each acre. Such a system can be handled much
more economically.

Where a considerable area of land is to be used for pa-
paya, or where a papaya plantation is combined with groves
and other types of crops, perforated slipjoint pipe can be
used. The pipe should be drilled on a definite pattern. The
holes should be 3/32 of an inch in diameter. Ten holes, one
foot apart, a half inch each side of the seam. Ten holes a
foot apart, one inch each side of the seam. Ten holes a foot
apart, an inch and a half each side of the seam.

This arrangement when fitted into a system with 6"
main line and two 5" 350-foot sprinkler lines of drilled pipe,
requires a centrifugal pump capable of supplying 500 gal-
lons of water per minute against the full head indicated by
pipe friction and elevation. The sprinkler lines are used
alternately. One set of 350 feet down and moved over one
place. In this way a strip of 350 feet of 5" slipjoint pipe
is sprinkling while the other set is being taken down and
moved over one place. In this way a strip of 350 feet long
and 30 feet wide will get the equivalent of a 2 inch rain
every 30 minutes. The operation of the system is con-
tinuous.
PLANT FOOD
In the matter of plant food requirements the papaya is
peculiar. It is a very rapid and very large growing plant.
Its necessities in the way of plant food of all characters are
large. It is, however, a soft, lush growing plant and very
susceptible to toxicity to too much concentrated plant food.
The toxicity point for the papaya is reached before the ca-
pacity of the plant to use food is reached with all three of

































jet:"c
,1
II I
laili
i*~''I


-- -,---. -' .-.

Specimen plant of perfect flowered character. Old type big Blue-Stem,
grown on scarified Oolite Limestone in Dade County under overhead irriga-
tion. Ten tons of waterweed compost used in making hills; 4'/2 tons of
5-8-10 commercial fertilizer to acre in 10 months. Vegetative growth very
much limited by soil conditions. Yield not appreciably affected. This illus-
trates the adaptability of this plant to widely different physical soil con-
ditions.










5' .


Ar


a F~

r


" r.w


Specimen plant old type big Blue-Stem, perfect flowered, grown on sandy
hammock soils on the peninsula at Wabasso, Florida. Soil of high organic
character, loose, well aerated, course sand, permanent moisture at 3, feet.
This indicates the capacity of this plant for vegetative growth where mois-
ture and plant food are not limited by the character of the soil or the physical
situation.


~b~F~








THE PAPAYA-A FRUIT 29

the principal plant foods, nitrogen, phosphorus, and potash,
if those plant foods are supplied as chemical ingredients.

It has been found advisable because of this peculiarity
of the papaya to build up a rather complicated feeding pro-
gram. The first step is to collect the material for a compost
pile. This compost pile should contain at least 10 tons of
vegetative trash of almost any character from stable ma-
nures to weeds and grass for each acre. It should, however,
contain enough manures to start decomposition when sprink-
led. Chemical plant foods for a year's fertilization of the
papaya field can then be added to the compost. The mois-
ture condition of the compost pile should be kept stable by
sprinkling. It should be kept moist, not wet. Nitrogen
should be added first in whatever form it can be purchased
the most economically as the heat recedes, phosphorus
should be added, and lastly, potash and any extra plant
foods such as copper, iron, manganese and zink that may be
found necessary for the immediate location.
The immediate result of this procedure is the working
over of chemical plant foods by bacteriological and micro-
logical (vegetative fungus) growths into organic forms un-
der the controlled conditions of the compost pile. It has
two very definite virtues in addition to the diluting of plant
foods in a mass of organic material so they are acceptable
to the papaya. It enables the grower to use the cheapest
chemical sources of nitrogen and still get the benefits of
organic nitrogen when applied to the field. It also results
in the chemical plant foods becoming so incorporated in
the organic structures that they do not bleach out readily in
case of heavy and continued rains. Once the compost pile
has been made and the process is finished, it may be held
in storage in piles and used as needed in successive appli-
cations.
Best results can be had by spading in a certain amount
of the compost before planting and then applying in fur-
rows a little farther from the hill each time in successive
applications as the plants grow and their root systems en-
large.
In contemplating the planting of papaya the grower
should bear in mind that each acre is going to take the








DEPARTMENT OF AGRICULTURE


equivalent in plant food of 3 tons of mixed fertilizer of the
analysis 5-8-6 during the first nine months of its growth.
At this point fruit ripening and returns in money should
commence. Also at this point a very common error occurs
in the handling of the papaya. It is very easy to look at
a papaya plant 10 feet high and 10 feet across the top, that
is 9 months old, carrying a cluster of 30 to 50 fruits, the first
of them getting ripe and assume that the job is done. A
little reasoning however, will show that this is completely
fallacious. To analyze the situation, suppose we presume
this is an average plant, has been well watered, well ferti-
lized, and carried 40 fruits, the largest of them is about ripe
and they weigh 3 lbs. Off of the smallest the blossoms
have just dropped and the fruit weighs an ounce. As a mat-
ter of fact if all of this fruit were taken off the plant and
weighed, it would not weigh more than 25% of what the
whole cluster would weigh if gathered at full size and ripe-
ness, so that aside from growing the plant, just 25% of the
work has been done. If the plant at this point is allowed
to go hungry or thirsty, it is entirely possible that not more
than a third of the fruit will size and ripen in good condi-
tion. Fertilization must be carried on at the same rate as
long as the plant is in bearing condition if maximum re-
sults are to be obtained.

FROST PROTECTION
There is no such thing in Florida as a totally frost free
location where a susceptible plant like the papaya is un-
der consideration. The site for the papaya plantation then
should be selected so as to require a minimum of frost pro-
tection. There are a number of factors in the matter of
natural frost protection that should be taken into considera-
tion in determining the suitability of each particular piece
of land.
The matter of air drainage due to elevation of the spe-
cific land under consideration and the contour of the sur-
rounding territory is probably the first item of importance.
The grower should always bear in mind that cold air flows
exactly like water and is governed by the same rules ex-
cept that its weight is less and for that reason the velocity
of flow is less. If the plot of ground under consideration
for papaya has a good slope, and there is a natural avenue








THE PAPAYA-A FRUIT 31

through which cold air can escape to lower levels, that will
accomplish much. Elevation of course is a factor of purely
relative value. Even a moderate elevation will be of tre-
mendous help if the territory all around is low and a con-
siderable elevation will be of no service if it happens to
be in a pocket, or even up on the side of a pocket into
which cold air can flow and fill up to the level of the land
in question.

Bodies of water of any considerable size particularly
if they happen to lie North and West of the land in ques-
tion are important helps in the matter of frost protection.
Take for instance, a lake approximately round and a mile
6r more across. The maximum frost protection will occur in
the quadrant exactly to the southeast of the lake and the
protection will diminish as you go around the lake either
way from that quadrant. To get full benefit from lake pro-
tection, the land should have some little elevation above
it so that cold air will flow towards the lake. Land that
has little or no elevation above the lake will be apt to be
just as cold as if the lake were not there. On the other
hand, if the elevation were here and the lake were not, full
frost protection could not be expected.
Two types of irrigation have been made use of for frost
protection in Florida and neither of them is of any real ser-
vice as frost protection for the papaya. Ordinary overhead
irrigation has occasionally shown fine results on other
crops. It has also shown some very severe losses. The dif-
ficulty seems to be that down to 32 degrees F. overhead ir-
rigation started in time and carried straight on through will
prevent damage. If, however, the temperature goes below
30 degrees, the water freezes either on the plants or in the
air, and if possible, more damage is done than if there had
been no irrigation.
Another method of irrigating for frost protection is to
pump ground water at a temperature of about 73 degrees
or canal water at about 2 degrees less into the furrows and
ditches in the flat lands. This works for some types of
crops. It is a total failure for the papaya as it results in
saturation of the ground and the rotting of the root system
of the papaya plants.








32 DEPARTMENT OF AGRICULTURE

ARTIFICIAL HEAT
Some form of artificial heat is the only sound method
of frost protection in dealing with papaya. There are two
outstanding methods of applying such heat and they differ
principally in the initial cost of equipment.
The first method is used where wood is plentiful and
cheap. The papaya plantation is usually squared off in 400
squares to the acre. In a hundred of these squares small
fires are built. Near each fire is a stock pile of wood ca-
pable of supporting the fire for the maximum duration of
two frost nights. This requires little or no equipment. It
is rather expensive in the matter of labor, however, but it
is easier to finance than the purchase of heaters. Properly
carried out it will take care of a papaya plantation down
into the lower 20s. In practice shavings soaked in distillate,
or turpentine kettle skimmings are put in 2-lb paper bags
so they are about half full. The bags are folded over and
tucked into the bottom of each small fire. These fires can
then be lighted whether the wood is wet or not by two or
three seconds application of the flame from a blow torch.

The use of the 9-gallon citrus heater burning distillate
or the coke heater burning petroleum coke requires con-
siderably more initial outlay. Sixty-five heaters of either
type are usually required to the acre. Distillate heaters
cost about $3.15 each laid down in Florida. The coke heat-
er costs about half as much. The distillate heater requires
fuel of low asphalt content that usually costs about 9c a
gallon. Unless good low asphalt content distillate is pur-
chased, soot will accumulate on the inside of the stacks of
these heaters and reduce their efficiency to about 20%.
Burning full tilt, these heaters consume 9 gallons of fuel in
9 hours. The coke heater has the advantage that it can be
fired continuously by simply dropping more coke into it.
The coke, however, is too expensive in Florida except near
a seaport.
Over a 10-year period the grower who systematically
protects himself against frost will be far ahead of the one
who does not. This is particularly true if the grower never
allows his disinclination to go out on cold nights to trick
him into an occasional loss.








THE PAPAYA-A FRUIT


Strict attention to the daily weather map on the part
of the grower and to the daily forecasts of the frost protec-
tion service will enable the grower in the course of time
to build up a very exact picture of the conditions under
which frost occurs on his particular piece of land.

An occasional fire or heater should be lighted through
the plantation at regular intervals at about 35 degrees F.
The temperature at the outside station should be watched,
and additional fires or heaters only be lighted as necessary
to keep the air moving and to keep the temperature chang-
ing.
FRUITS
There are many varietal forms of carica papaya grow-
ing both fortuitously and under cultivation in Florida. It
should be definitely understood in advance that the vast
majority of these varietal forms do not have the grouping
of fruit characters necessary to be useful for commercial
purposes. Most of them in fact are absolutely useless from
the commercial standpoint.
The palatability of a given varietal form of papaya is
the most important single factor in judging the commercial
value of that variety. It is an unfortunate but very defi-
nite fact that the vast majority of the varietal forms of pa-
paya now existing in Florida are contaminated with the
blood of the wild papaya. This has a definite bearing on
the matter of palatability. The wild papaya has a distaste-
ful odor and flavor. The blood of the wild papaya even
though attenuated by a number of crosses is sure to result
in this musky odor and flavor cropping out in any varietal
form of domestic papaya.
It is a very common occurence to hear people say, "I
don't like that papaya flavor." Now what they speak of as
"that papaya flavor" is the musky odor and flavor of the
wild fruit. This contamination with the wild is so common
in Florida that very few people realize that this unpleas-
ant flavor is in no way an essential part of the flavor of
domestic varieties of papaya.
Most of the varietal forms of domestic papaya when in-
troduced to Florida are free of this odor and flavor. By the


33








DEPARTMENT OF AGRICULTURE


same token regardless of how good they taste in the first
generation, in two or three generations they will cross out
to the wild and in that acquire this flavor. Too much stress
cannot be laid on the fact that this contamination by the
wild papaya is an unnecessary situation. There are now
types of papaya available for use in Florida that are the
equivalent of the nicer cantaloupes in palatability. The
scientifically minded grower can now select his seed plants
for the perfect flowered character, bag their flowers, and
maintain his type for an indefinite number of generations
in as pure a condition as he received it. He can also by se-
lection take advantage of the occasional plant that occurs
that is better than the run, bag its flowers and improve his
type.
The size of a commercial papaya is ruled by one thing,
the price that the public will pay readily for a single fruit.
Now as papaya sell on the market from 8c to 15c a pound
the size fruit that will sell best is one from 2 to 3 lbs. in
weight. Experience has determined that the public will
pay 25c each very readily for papaya. They will even go
to 35c or 40c, but when the half dollar point is passed, sales
resistance commences to increase. Papaya weighing from
6 to 10 lbs. are almost unsalable except to the papaya fac-
tory.
In shape the ideal commercial papaya should be as near
oblong cylindrical as possible. This is a matter of the shape
making a uniform pack. Cylindrical fruit within the ideal
weight limits can be so graded as to make about four packs
of uniform size. Cylindrical fruits carry better in the pack-
age as their weight is borne along one side rather than at a
point as is the case with spherical fruit.
The ideal commercial papaya should have thick, firm
flesh, regardless of how small the fruits may be. This also
has a bearing on the matter of how the fruit resists stress
within the package. A fruit that is cylindrical, is thick
fleshed and whose flesh is firm even when full ripe will,
when properly packed, ship long distances and arrive in
good condition.
The flesh texture of the ideal commercial papaya should
be smooth, crisp, and free from fibre. This factor of texture








THE PAPAYA-A FRUIT


of flesh bears particularly on the matter of papaya products.
Texture is of course also important in the matter of palata-
bility. The wild papaya among its other sins has the faculty
of transmitting to its progeny even where a very small part
of the wild blood is concerned a grainy salve-like texture
to the fruit that is very unpleasant in the mouth, even when
its flavor is good. Fruit of smooth, fibre-free, firm, crisp,
juicy flesh, when full ripe, results in an ideal texture char-
acter of fruit for all purposes. Green fruit of such charac-
ter makes pickles, preserves, and crystallized fruits that are
clear, translucent, of good firm texture, but not tough. This
same character of fruit will become full color as to flesh
while still being firm and unripe. In that condition it can
be used for the same list of products, and the only difference
in the products will be the color. This same character of
fruit when full ripe to the point of being ready to eat, re-
sults in smooth marmalades, jams and butter of good color.

The matter of a natural sugar content in the papaya is
primarily a matter of variety, second, a matter of soil, and
third, a matter of climate situation at the time of ripening.
A vast majority of the ordinary papaya offered for sale in
Florida are of poor sugar content as a matter of variety. A
deep sandy soil, plenty of organic plant food, regularly sup-
plied moisture, and perfect drainage will result in the
best sugar content possible for the variety. Cold weather
at the time of ripening will result in poor sugar content in
most of the varietal forms of papaya. It has been noticed
in Hawaii that even a prolonged rainy spell accompanied
by dark cloudy weather has a detrimental effect on the su-
gar content of most varietal forms of the papaya.
A single varietal form of papaya coming from Merida
in Yucatan has an unusually high sugar content and the
capacity for retaining that sugar content even in dark, cold
weather. This peculiarity is well enough established to
transmit to hybrids with this strain along with several oth-
er specific characters. Fortunately this strain can be iden-
tified even in hybrids by a color peculiarity of the plant.
The plant stems, leaf stems, fruit stems, and the scars left
on the base of the fruits by the petals of the flower, are a
rich dark purple. This varietal form has been introduced
to Florida from several sources, from Yucatan, from the








36 DEPARTMENT OF AGRICULTURE

Philippines, and from the Canal Zone. In all probability it
originated in the district immediately around the ruins
known as Chicken Itza in Yucatan. Hybridizations with
this strain of papaya have resulted in all of the Blue-Stem
varieties in Florida.
PLANTING
It should be borne in mind that the growing of papa-
ya seedlings is an involved and technical problem. The
plants are weak and susceptible to disease, destruction by
insects, and the seeds just at the point of germination will
be dug up and eaten by rats and mice if they get half a
chance. They pay no attention to them until they start to
sprout, but once they start to sprout, the seeds will be dug
up by the thousand in a single night unless precautions are
taken.
The planting of papaya seed, any transplanting opera-
tions to pots or flats and the growing of seedlings up to the
time they are ready to go into the field must be carried on
under partial shade. The shade should be gradually dimin-
ished to prevent them betting tall and spindly, but the young
plants must have some shade.

The seed may be pre-germinated in a flat and potted up
just as they crack showing the white of the seed through
the seed coat. This is accomplished by filling a flat with
potting soil, firming it down with a block of wood to a
smooth firm bed. A thousand seed may be scattered on the
surface thus created in an ordinary tomato lug or green-
house seed flat. The seed should be pressed lightly into
the surface of the soil but not covered with soil. Next three
or four thicknesses of burlap should be cut the size of the
top of the flat, soaked for an hour, wrung free of surplus
moisture, laid over the top of the seeds. A sheet of heavy
paper should go over the top of the burlap. Under ordinary
conditions they will not have to be moistened but the sur-
face of the soil should stay moist. This can be checked by
raising the corner of the burlap. Some seeds will start to
crack about the eighth day. After that the flats should be
gone over each day and those seeds that have germinated
be picked up, placed in a depression in a soil filled three-
inch pot, and covered with about a half inch of soil.








THE PAPAYA-A FRUIT 37

When a flat has been gone over, its burlap cover should
go back and it should be sprinkled lightly. The seeds will
come up in the pots in four or five days. This system gives
the advantage of plants starting in the pot in which they
grow without the difficulty of potting up seed that does not
come up.
Where seedlings are grown in flats, the flats should be
filled with soil, furrows "/4 deep and 3" apart made in the
soil, the seeds drilled so that about 100 seed go in a tomato
lug or an ordinary seed flat. The seeds are covered, the soil
firmed down and it is good practice to lay a sheet of heavy
paper over the flat to prevent evaporation. If properly
handled, the flats will not have to be wet more than once
between planting and the time the seeds start to come up.

All planting operations of papaya seed and any pot-
ting operations to be done thereafter should be done with soil
of loose coarse texture, containing plenty of organic mater-
ial, little or no chemical fertilizer, and that has been care-
fully sterilized for namatode control. This can be done with
formaldehide, formaldehide dust, sulphorcide or even with
raw sulphur.

When planting papaya seed in open seed beds with
partial shade on a rack over them, the seeds should be
drilled thickly in rows about six inches apart, half to three-
quarters of an inch deep. Three rows of seeds usually drilled
on a narrow bed 24" wide and slightly raised above the
surrounding soil.
In watering of papaya seed flats, papaya in pots, or in
open seed beds, one rule should be followed and that is to
drench them thoroughly and then not water for several
days. The plants should not be allowed to become distress-
ed but the system should be followed of allowing the flat
beds or pots to dry out every few days.
Plants no matter how grown should never be allowed
to leg up because they are too thick. They should be potted
or transplanted to wider space as soon as they have four
leaves. They should be well shaded at first and then the
shade reduced as fast as they can stand it to keep them
stocky and hard.








DEPARTMENT OF AGRICULTURE


When plants in pots are 4" to 6" high carrying 6 or 7
leaves, the last two of them character leaves, they are ready
to go into the field. It is definitely an erroneous practice to
grow plants to more than six or seven inches high before
they go to the permanent location. Plants that are allowed
to get 14" or 15" high, and then transplanted, will be sure
to go high and thin before time to fruit. This interferes
radically with the capacity of the plant to set and carry a
good load of fruit.

The papaya field should first be marked out with pegs
where the hills are to go. Papaya plants should not be set
closer than 8' x 8' on the square under any condition and
10' x 10' is probably a better distance. A well fed, well wa-
tered papaya plant of vigorous ancestry, 9 months old,
should be 10' high and 10' across the top. The lighter the
soil, the harder moisture is to get, the smaller the top will
be, but it is probably safe to say that 8' x 8' is as close as
they should ever be set.
The spring planting of papaya with small plants grown
through the winter is the common practice, largely because
it results in a crop so timed as to give the bulk of the first
flush of the fruit during the tourist season of the following
winter. It is sound practice, except for one thing. Where
the hurricane is a problem it exposes the plants to the hur-
ricane season with a full crop of fruit on them. If they are
blown out, they are blown out completely and without hav-
ing made any return.
The setting of papaya plants in the fall is receiving
some attention. It requires a different sort of plant. Plants
for this purpose are grown from seed germinated in May
and June, set about a foot apart in nursery rows three feet
apart, very often in a mature papaya planting. Because the
plants are competing, they will grow up tall and thin, and
bloom early. Once they bloom, the males, females, and
other undesirables can be rogued out leaving only the per-
fect flowered plants having desired characters. Late in Au-
gust the plants will be 21/2' to 3' high and from 3/4" to 11/4"
caliper of stem. During the last week in August, such plants
can be cut back to 8" stumps; they will promptly develop
suckers. The best single sucker is left, the rest rubbed off.








THE PAPAYA-A FRUIT


These short, stumpy plants, with new tops, about 6" or 8"
across can be set in October or even from then on till the
15th of February, will make a good root system and grow
off rapidly, making a considerable quantity of late summer
fruit. The principal criticism of this practice is that where
frost is the principal hazard, frost protection must be re-
sorted to before any money has been received.

Almost regardless of soil condition or season, the hills
for the planting of papaya should be made by hoeing out a
saucer 6" deep and 22" across. In the bottom of this sau-
cer a good big shovelfull of well decomposed compost should
be spaded. The saucer should then receive a mulch of dry
grass a foot deep in the center of the saucer and extending
well out over the edges of the rim.

In planting these saucers, it is well to wait till three
days after a rain or add about five gallons of water to a
hill and then wait about three days. The plants should be
set in a hole in the mulch made by simply pushing the grass
away from the peg down to the ground. This hole should
not be over 10" across and the plants set in the soil at the
bottom.

When the plants are 2' to 2%' high, furrows should be
plowed down each side of the row right against the edges of
the mulch pans. Into these furrows compost to which chem-
ical plant foods have been added should be shoveled at the
rate of five tons to the acre and covered with the plow.
This should take care of the plants until fruit setting is well
started.
PEST AND DISEASE CONTROL
The matter of pest and disease control in papaya cul-
ture does not present any very serious difficulties. The
grower should know in advance what pests and diseases he
is apt to encounter and do more prevention work than cur-
ative work.

There are only two diseases of any importance affect-
ing papaya in Florida: The papaya leaf spot, which makes
its appearance in the form of thousands of small blackish
or brownish spots or pustules on the under sides of the







40 DEPARTMENT OF AGRICULTURE

leaves particularly as they become old. The other one is
the development of anthracnose spots from a half inch to two
inches across. These spots appear as the fruit commences
to ripen and sugars develop near the skin. They are tough,
blackened, sunken areas. A knife may be slipped under
the edge of them and the affected tissues lifted right out,
leaving a clean hole from a quarter to a half inch deep in
the flesh of the fruit. This destroys the marketable char-
acter of large quantities of fruit.

Both the leaf spot and anthracnose can be controlled
by regular application of 3-3-0 bordeaux. It is recommend-
ed that homemade bordeaux prepared with rock lime be
used for this purpose. Spraying should commence as soon
as the plants are three feet high, and continued at regular
intervals, depending on the rapidity of the growth of the
plants. No great amount of new growth should ever be
left exposed for a very long time. The underside of the
leaves, the stems, and the trunks of the plants should be
kept well sprayed, up to and including the bud.

PAPAYA FRUIT FLY
(Toxitripana Curvacauda)

This fly has been held over the heads of papaya growers
as something of a bogey. As a matter of strict fact the con-
trol of this insect is a comparatively simple matter. It is
entirely a matter of the character of fruit grown. It just
happens that the character of fruit necessary to beat the
fruit fly and the character of fruit necessary to satisfy the
needs of commerce are one and the same.

Edward Simmons of the old Brickell Garden of the
Bureau of Plant Industry at Miami discovered 30 years ago
that the papaya fruit fly did not colonize fruits having an
overall thickness of flesh of 5/8 of an inch or better. For a
long time it was a question whether this was just a matter
of preference on the part of the fly or not. The facts have
been established thoroughly by this time.

The papaya fruit fly is a wasp. The female has a long
curved ovipositor or egg tube. In laying eggs this fly sticks








THE PAPAYA-A FRUIT 41

the ovipositor into the flesh of mature but unripe papaya.
The ovipositor will penetrate a trifle over a half-inch into
the flesh. At this point the curve stops it. If when the first
egg is laid, it falls into the cavity in the center of the fruit,
15 to 40 eggs are laid that hatch out into larvae. The larvae
feed for approximately 21 days on the green seeds and the
aril which surrounds them. The larval period may be ex-
tended a few days in cold weather or shortened a few days
in very hot weather.

At the end of the larval period the larvae drill out
through the bottom end of the fruit, dig into the ground
and pupate. Now the reason why thick fleshed fruit will
defeat the papaya fruit fly is right here: The flies cannot
dig their way out of an unripe fruit. The fruit must at the
end of the larval period be in the condition of starting to
get ripe. This is why only mature fruits are colonized. If
the fly could lay eggs and the larvae emerge successfully
from green fruit of any size, there would be no point in at-
tempting to grow papaya where this fly exists.

Suppose, for instance, a fruit has been colonized that
is too green. This occurs once in a while. This writer has
observed a half dozen cases in 20 years. The larvae hatch
and feed on the green seeds and the aril in the normal way,
until the end of the larval period. They then attempt to
drill their way out of the green fruit. The result of their
drilling is the exudation of the papaya latex into the seed
cavity. The enzyme papain in the latex promptly digests
the larvae. Such a fruit will show a peculiar greenish yel-
low color on the plant and when opened will be found to
have 25 or 30 brownish shells that are all that is left of the
larvae.

All that is necessary to completely defeat the activities
of the papaya fruit fly is to grow fruit having an over all
thickness of flesh of 5/8 of an inch or better. As this coin-
cides with the necessities of good commercial fruit, it is a
routine matter.

It is probable that no amount of spraying or baiting or
trapping will eradicate the papaya fruit fly from Florida.
This wasp uses the thin fleshed wild papaya as a host plant.








DEPARTMENT OF AGRICULTURE


It is not much of a traveler. For nearly 10 years after the
'26 hurricane there were no papaya fruit flies at Miami as
all the wild papaya were destroyed along with the domestic
ones and too long a period elapsed before new fruits appear-
ed for the fly to bridge over. The progress of the papaya
fruit fly northward from lower Matecumbe Key a few miles
each year could be accurately traced until now the fly is
well established in the Miami area again.

The female of this wasp seldom eats during her entire
life. When she emerges from the pupa case she flies out
and breeds. Flies around a few days in search of papaya
plants, deposits her eggs and dies.

The male will sometimes eat poison syrup. It is how-
ever probably a grand thing for the budding papaya indus-
try that we don't have to spray for this particular insect
as at the present no adequate measure except to destroy
host plants is known. If there were any reason for growing
papaya that were thin fleshed enough to be colonized by
this fly, the complete eradication of the wild papaya and
their systematic suppression in the neighborhood from the
time the plantation was set out would be sufficient to elimi-
'ate this fly from the specific locality. It is hard to see,
however, why anybody would want to grow a papaya thin
fleshed enough to be subject to the attacks of this insect
as such a papaya would be unsuitable for any commercial
purpose.

There seems to be a specific white fly for the papaya.
This, probably the worst insect pest the papaya grower has
to deal with. Once thoroughly established, the white fly is
very hard to eliminate. If proper vigilance is used and
the undersides of the bud leaves of each plant are examined
about every ten days, the first few flies will be detected.

It is not advisable to use oil emulsions on the papaya
either alone or in combination except on the advice of a
technician connected with the company that prepares the
emulsion. It is probably better to use dusts or sprays con-
taining contact poisons. The white fly is not difficult to
control if control measures are started early. The first








THE PAPAYA-A FRUIT


time a few insects are detected, contact poisons can be add-
ed to the bordeaux.

The papaya grower with any quantity of plants to care
for should have a competent spray technician work out a
formula for him for his own district. It should be possible
to fix up a compound spray that will take care of all of his
difficulties, provided, of course, he mixes persistence with
his spray.

The horn worm, tomato worm, tobacco worm, or what-
ever you want to call him, depending on where you are, is
very large, green, fleshy worm with an enormous appetite
and will completely defoliate a young papaya plant in a
single night. He is so colored as to be a little hard to see,
but so large, and makes such large tracks in the way of de-
stroyed leaves, that this worm is comparatively easy to find
and kill. They seldom seem to be present in any number.

There is also a worm said to be the corn ear worm that
establishes itself in the fruit cluster as the papayas grow.
Its favorite hiding place is between a large fruit and the stem
of the plant and it builds a protective wall around itself of
manures. This makes it almost impossible to get at it with
sprays. If the fruit cluster and the plant stems are kept well
enameled with bordeaux containing a little arsenate of lead
or calcium arsenate, this worm will never get established.
Once he does get established, about the only way to get
him is to tie a bunch of turkey feathers together, making
a stiff brush. This brush dipped in an arsenical spray may
be wiped on the plant stem and the back of the fruit by
lifting the fruit away from the stem a little bit. This is a
lot of trouble, but if thoroughly done a couple of times, will
eliminate this pest.

PAPAYA PRODUCTS
The matter of papaya products, their manufacture and
sale is becoming more important each year. It has already
become a trade of considerable importance, particularly at
Miami and Tampa. There are several concerns which make
the papaya their sole business. There are many others
which make papaya products along with a list of jellies
.and jams.








'44 DEPARTMENT OF AGRICULTURE

At the moment there are on the market papaya jellies,
marmalades, crystallized fruits and syrup for the making of
drinks on the market. The manufacture of frozen papaya
pulp for the ice cream trade has been attempted several
times but has not been a complete success apparently for
the lack of large quantities of fruit of uniform character
necessary for such a trade.

The fact that large quantities of papaya of uniform
character have not been available in Florida is probably
the principal reason why the matter of papaya products
has not gone ahead more rapidly. Until the time arrives
when large quantities of papaya are available at all sea-
sons and those papaya are of fairly uniform fruit character,
the products things will probably not gain a great deal of
momentum.

It will take the adaption of the papaya to a much wider
range of territory in Florida to accomplish this result than
is now the fact. Seems quite probable that it will be worth
while to go to a good deal of effort in the central and north-
ern part of the citrus belt to protect papaya from occasional
frosts in small areas that are particularly suited to them
rather than to attempt to grow them in the coastal areas
where the occasional storm wipes the grower clear out.

The knowledge of what kind of papaya products to
make and how to make them seems to have outstripped
the production of papaya. The facts regarding the manu-
facture of a considerable list of papaya products are already
known. There is considerable knowledge of just how sal-
able those products are and how much money they will
bring. There is not at the moment, however, a source of
papaya of either quantity or character suitable for these
products.

Considerable quantities of pasteurized pulp of the full
ripe papaya have been imported into Florida from Cuba for
the manufactured products. This is unfortunate from sev-
eral angles. In the first place the Cuban product is very un-
uniform. One five gallon can will contain a pale yellow
liquid that the hydrometer says is little better than water.
The next can will contain what looks like canned pumpkin.








THE PAPAYA-A FRUIT


so heavy that the hydrometer will not even measure it.
Both from the standpoint of the Cubans are five gallon cans
of papaya pulp. Some cans were found that had actually
been adulterated with the cooked pulp of sweet potatoes
and water.

Crystallized papaya can be used as a candy, can be used
in the making of fruit cake or in any way that the crystal-
lized skins of citrus are used.

Crystallized papaya is made from papaya fruit full size
but green and full size, full color, but still hard because
unripe. There are two processes used. The commonest one
is to cut the fruit, remove the seeds, boil in plain water
until tender. The fruit is then placed in a 20% sugar syrup.
Every three or four days the fruit is removed from the
syrup, the syrup brought to a boil, and the percentage of
sugar raised a little in each process. Different manufac-
turers have different ideas as to how fast to raise the per-
centage of sugar. Some make two or three processes of it.
Some raise it gradually in about ten steps. This takes a
period of almost three weeks. This product is apt to be
flaccid and very much distorted as to structural appearance.
The other process is to cut the fruit in half, pack it in bar-
rels, covered with brine that will float an egg. It takes
from ten days to three weeks in this pickling solution for
lactic acid fermentation to finish. As soon as the bubbles
stop rising, the fruit must be removed from the pickle,
freshened and crystallized. A rack of wood should be so
arranged as to hold all of the pieces at least six inches be-
low the surface of the pickle. Any pieces that come any-
where near the surface will become soft and slimy and can-
not be used. The fruit should be taken from the pickle and
freshened 8 or 10 hours in running water. It is then brought
to a boil in plain water, cooked until tender to a fork, drain-
ed out of the boiling water, placed in boiling 20% sugar
syrup, allowed to boil for 10 minutes and set aside. Every
second day the syrup should be poured off of the fruit into
a kettle and brought to a boil. Its sugar content should
then be raised by adding 10% of its total volume of heavy
syrup. Make the heavy syrup by adding one pint of water
in which 15 grains of citric acid have been dissolved to 12
lbs. of sugar, melt cautiously as in a steam kettle to prevent








DEPARTMENT OF AGRICULTURE


burning. This syrup will not flow at ordinary temperatures.
The grated rind and juice of any variety of citrus can be
used in making this heavy syrup instead of water and citric
acid.

Sweet pickled papaya and preserves are made from the
same character of fruit as is used for crystallization and are
made in the same manner as watermelon pickles and pre-
serves. This recipe can be found in any cookbook.
In making products from the ripe fruit of the papaya
it is always best to mix the fruit and sugar raw and set in
the icebox overnight before the first cooking.

Papaya Marmalade. Papaya full ripe to the point of
softness should be cut, peeled and mashed raw through a
colander. To this may be added the grated rind and juice
of any variety of citrus to suit the taste of the maker. Cup
for cup of sugar should be added to the mixture. Set in the
icebox for 24 hours, cook and bottle.

Papaya Preserves. Fruit that is full ripe and a trifle
firm should be peeled and diced carefully so as not to mash
up. Equal parts of sugar and fruit placed in a bowl. Over
it pour the grated peel and juice of any variety of citrus,
set in the icebox for 24 hours, cook and bottle.

By using different varieties of citrus for flavoring, a
considerable list of products of varying flavor can be made
in this manner.

Papaya Drinks. There has been a procession for the
past 10 years of companies undertaking to make still and
carbonated drinks from the papaya. The goal of all of these
efforts has been to make a drink that would have the di-
gestive character of the active enzyme contained in the
fresh fruit and that could be sold legally as a health drink
for that reason.

Some of these efforts have been carried out by people
of technical knowledge and experience and honesty of pur-
pose; some of them by people who have none of these quali-
fications. All kinds of processes have been resorted to. In
some cases the papaya, skin, seeds and all was put through








THE PAPAYA-A FRUIT 47


a squeezing process to give up a filtered juice and the po-
mace used for other purposes. These efforts to express
juice from the papaya have all been unfortunate. Little re-
sults from such a process but dirty water, the reason being
that the flavors and sugars are tied up in chemical combi-
nation with the matter in suspension and are not to any
extent in solution. Efforts that started out along this line
have ended up more or less in the same class as citrus
punches flavored with all manner of synthetic essences
based on dirty water squeezed out of the papaya.

Another class of these drinks of somewhat better char-
acter have been made by pulping the papaya, adding sugar
and citrus flavor, and merchandising them. This class of
drinks have mostly been made and sold fresh on a local
basis. Some efforts have been made to add enough of some
sort of preservative to the papaya pulp, usually benzoate
of soda, so that it will keep without cooking. This is a
practice of doubtful value. Some research work has been
done on processing the pulp of the papaya so that it will
keep and be later mixed with syrup water and citrus fla-
vor to be sold as a drink. There seems to be some possibil-
ity of success along this line and staying within the regu-
lations of the Federal Pure Food Laws.

The flesh of the full ripe papaya that has been put
through a pulping machine can be mixed with 10% sugar,
frozen in a brine type ice cream freezer to about the con-
sistency to which ice cream is frozen before going into the
containers. This product can be run into 5-gallon cans or
50-gallon barrels, set in a hardening room of an ice cream
factory for three or four days and become a base product.
It can be used for a number of things. It can be shipped in
the regular channels of trade under refrigeration. It must
be held at 26 or below either in storage or in transit as it
will not stay frozen above 26. This product can be used in
the making of ice cream by using 1 gallon of the frozen pa-
paya, 4 gallons of base vanilla mix without any vanilla.
This makes a trifle over 9 gallons of papaya ice cream. It
has the appearance of peach ice cream, a pleasant but not
very strong flavor. It has digestive action of the fresh pa-
paya and for that reason is entitled to sell as health ice
cream.








48 DEPARTMENT OF AGRICULTURE

This frozen papaya can be thawed out and used as a
base for making papaya drinks or papaya marmalades and
jams with citrus flavors. This product can also be made
into a mixture for making papaya ice cream sundaes or can
be used for this purpose just as it comes from the barrel.

DIGESTIVE FACTORS
The fresh fruit of carica papaya when full maturity has
been reached but the fruit is still unripe yields a consid-
erable quantity of milky juice or latex when the fruit is
scratched. This latex contains a small percentage of an
enzyme called papain. Papain behaves in the human stom-
ach as does animal pepsin, in that it digests comparative-
ly enormous quantities of proteins when its own weight was
considered. This enzyme seems to be equally active in an
acid or alkaline medium.

The percentage of latex in the fruit is greatest at the
point of full size of the fruit but before any tendency to
ripen has occurred. The percentage of latex declines grad-
ually from that point down to full ripeness. The full ripe
fruit does, however, contain in its flesh a small percentage
of this digestive enzyme. For this reason the ripe fruit of
carica papaya has been used for centuries in the tropics as
an aid in all sorts of stomach disorders having their origin
m the lack of the capacity of the individual stomach to di-
gest proteins. The use of the dried latex in medicines for in-
digestion of all sorts has increased to enormous proportions
in the course of the last 50 or 60 years. The use of this pa-
pain either as fresh fruit or as a drug is too well established
and too thoroughly understood to be even subject to ques-
tion.

There are, however, certain misunderstandings that
should be corrected. The statement has been repeatedly
made in print and commonly disseminated by word of
mouth that the seeds contain pepsin. This is a complete
error. The seeds contain an essential oil of complex char-
acter composed mostly of oil of mustard, a certain amount
of oil of nasturtium and other derivatives that have not
been catalogued up to the moment. These last may be na-
tive to the seed of the papaya. This oil is not an aid to di-















- 1


6iI


A display of papaya in a fancy grocer's shop in San Antonio, Texas. This display is of the Blue-Solo variety.
Fruit of the second hybrid generation. This fruit was wlappeu in celophane and packed in fruit lugs bedded in
excelsior. The packages held three, five, six or eight melons, depending on the size and variation in fruit shape.
This picture indicates the willingness of merchants to cooperate with growers in the matter of promoting the sale
of papaya.


--------~ --








50 DEPARTMENT OF AGRICULTURE

gestion, has a violent and somewhat detrimental effect on
the activities of the kidneys and certain other glandular
structures. The latex containing the enzyme exists in great-
est quantity just under the skin of the fruit but exists in
small quantities all through the tissues of the plant except
in the seeds and the membranous aril surrounding the seeds.

The occurrence of this enzyme has the peculiar effect
of protecting the papaya from the attacks of all types of
fruit flies except the specific fruit fly for the papaya (tox-
itripana curvacauda). When fruit flies lay their eggs be-
neath the skin of the papaya the eggs are digested and no
larvae hatch out. This is true up to the point of decomposi-
tion of the ripe fruit. Once the flesh of the full ripe papa-
ya commences to decompose and break down the enzyme
has entirely disappeared and such overripe fruit can actual-
ly be used as a medium in which to grow the larvae of fruit
flies. The larvae of the papaya fruit fly must hatch in the
cavity and feed on the green seeds and the aril surrounding
them, not the flesh of the unripe papaya.

The fresh fruit, the dried latex collected from green
papaya, the frozen pulp of the ripe papaya and some of the
concentrate syrups made for the drink trade contain the
active enzyme papain. Any product that has been subject-
ed to ordinary cooking temperatures loses the activity of
the enzyme.
PAPAYA SALES
The papaya will of course be grown for profit if at
all. This matter of where and how and what kind of pa-
paya are salable is probably more important to the pros-
pective papaya grower than any of the factors controlling
the growth of the papaya. The salability or lack of it of
this fruit must of course be taken into consideration from
the beginning in growing.

Previous reference has been made to the fact that papa-
ya have existed in Florida of more or less edible character
ever since white men have been here. It is practically im-
possible at this point to avoid the remark that they were
mostly less edible.








THE PAPAYA-A FRUIT


It is true that the papaya is a boon to those people who
suffer from indigestion in any form. It is also true that a
certain amount of the people will eat the papaya for medi-
cine because of this fact regardless of how nasty it may
taste and smell. Vast quantities of papaya are eaten every
winter season in Florida because of their medicinal value
that would be labeled outright nasty if it were not for the
digestive character of the fruit. So much for that. It un-
questionably gives the papaya a tremendous sales advan-
tage. The papaya will never, however, become the subject
of a large national trade fresh or as a product except as an
improved fruit that is really palatable as well as healthful.
The papaya grower will do well to make sure that his pa-
paya enterprise is based on seed or plant stock whose an-
cestry is known and whose history is for the production
of fruit that is really edible. It is the experience of this
writer that nothing is necessary to make a good papaya
palatable except a spoon to eat it with and that no amount
of doctoring will make a musky odored and flavored papaya
really fit to eat.

The matter of shipping quality in the papaya of course
bears directly on its salability. A papaya type to be com-
mercially feasible must have a ripening period after being
taken off of the plant of a minimum of say six to eight
days. There are such varieties. By far the vast majority
of papaya varietal types show a little color on the plant
today and are soft tomorrow. Such papaya of course are
of no service commercially.

During the time that tourists are in Florida there is
a large and mostly unsatisfied market for papaya of good
dessert quality. This market commences about December
1st, reaches its peak about February 15th and has a very
decent carryover to the 15th of May. The hotel trade in
some of the larger tourist centers of Florida is now being
supplied largely through the importation of many thousands
of dollars worth of papaya from Cuba each winter.

The improved varieties of papaya have found their
way in a sporadic fashion to the Northern markets. When
they were properly packed and arrived in good condition,
they brought the grower very fair prices. The biggest dif-


51







DEPARTMENT OF AGRICULTURE


ficulty to date with this matter of shipping papaya North
has been the unreliable character of the sources of papaya.
They would be on the market for a few months and then
disappear for a year. Of course no sound trade can be built
up on this basis. Here again it would seem to be essential
that the papaya be produced over a wide enough territory
in Florida so that some local climatic disturbance would not
take it entirely off the Northern markets.

Strains of papaya now exist that can be depended on
to produce fruit of fairly uniform, dessert and commercial
character. From this point out diligence and intelligent
effort in the matter of working out cultural schemes that
will keep these improved sorts of papaya on the market
continuously seems to be the necessity.

PICKING. PACKING AND SHIPPING
The general run of papaya grown in the State at the
moment varies so widely in all characters that there would
be no possibility of making recommendations for the hand-
ling that would fit the general crop. The following rec-
ommendations are made for papaya of known line bred
character from perfect flowered plants only. They will
not fit for any other character of papaya.

The papaya is ready to come from the plant at the first
show of color in the creases at the blossom end. At this
stage the fruit will be hard and will show little or no change
of color anywhere else.

It should be remembered in handling the papaya that
this fruit practically has no skin. The skin is so thin and
tender that the slightest roughness in handling will result
in a bruise that breaks the skin and will cause damage as
the fruit ripens. The fruit should be picked from the plant
and wrapped immediately. A good way to do this is to
wrap the fruit in a sheet of old newspaper as it comes from
the plant and lay it in a field box.

The fruit should then go to the packing shed, be laid
out on benches, burlap covered and padded, graded for size
and shape, wrapped, and packed firmly in excelsior. The








THE PAPAYA-A FRUIT


wrap can be anything from cellophane to eggplant paper.
Cellophane adds enormously to the appearance and sala-
bility.
The matter of a standard package for papaya has not
been definitely worked out. The fruit lug makes a good
small package. For a larger package a box will probably
have to be developed. A package to hold 2 dozen papaya
of the long type standing on end would probably be a good
type. Such a package would have to be built in about
three sizes and depths: 14 x 20 and 10 inches deep would
take care of the small size; 18 x 26 and 12 inches deep would
take the next size; 24 x 30 and 14 inches deep would probab-
ly take care of the larger melon. These cases would hold
approximately 48, 60, and 72 lbs. of papaya net. Such cases at
the moment are purely theoretical. They have never been
used. They are suggested by the fact that the old big, Blue-
Stem used to be packed 10 mellons to a pepper crate stand-
ing on end.
SHIPPING CHARACTER
The improved types of the papaya are quite hard when
they are ready to come off the plant. They ripen in such
a way as to allow from 8 to 12 days after coming off the
plant before they are ready to eat.

The full ripe papaya shows very little tendency to
spoil at icebox temperatures even after it has been cut.
This fruit can be kept 8 or 10 days after it has reached the
stage of edibility at anything below 50 degrees F.

The unripe papaya no matter what degree of maturity
will never go on ripening if it is chilled for any appreciable
time below a temperature of 60 degrees F.

Efforts to ship the papaya North in a mature but un-
ripe condition must be confined to the summer time or
they must go in heated cars.

The papaya can be allowed to get full ripe, precooled,
packed and shipped under refrigeration and will keep for
8 or 10 days. This is probably the only feasible method
of shipping the papaya North in the winter time. Many








DEPARTMENT OF AGRICULTURE


disappointments have resulted from the shipping of green
papaya which laid around for weeks and would not ripen.

WHEN IS THE PAPAYA RIPE?
The papaya is full ripe and ready to eat when a light
pressure of the ball of the thumb causes the flesh to break
away under the skin and leave a dent. This is the only
test of any value. The fact should be stressed that the
pressure should be light. The papaya ripens next to the
seeds first. Ripeness progresses through the flesh to the
skin. Just as long as there is any tendency to rubberness
or elasticity to the skin the fruit is not clear ripe, that is,
if a dent is made by the thumb, and when the pressure is
removed, the dent fills up, that fruit is not ready to eat.

Color is no indication of ripeness in the papaya. Some
papaya such as Solo turn a clear pumpkin yellow and are
hard as rocks, being still unripe and not fit to eat. Some
papaya ripen with an entirely green skin. One variety
particularly that has shown up as a sport among hybrids
shows only a slight appearance of sunburn over the exposed
side of a very dark blue green skin. At this point the melon
is ready to come off of the plant. The layer of flesh next
to the seeds is rich orange in color and it will ripen full
quality off the plant taking 8 or 9 days to do so. The grow-
er will have to learn to know the ripening peculiarities of
his particular papaya.









THE PAPAYA-A FRUIT 55




The Fruitful Papaya

(Prepared by State Home Demonstration Office at
Florida State College for Women,
June, 1938)

Papayas are on the markets of South Florida during
the entire year barring unusual weather conditions such as
frost and heavy rains. The supply, quality and flavor of
papayas vary considerably and for most people the taste
must be acquired.

In the full ripe state the papaya makes a delectable
breakfast or dessert fruit, served with lemon or lime. In
cocktails and salads it combines deliciously with pineapple
and citrus fruits. The fresh papaya pulp with milk or
cream makes a most delicious frozen dessert. Sliced and
seasoned in the same way as peaches, papayas are used for
pie, or, with the ripe pulp put through a sieve and milk,
eggs and spices added, for a custard or as a squash pie. The
papaya ranks high as a pie fruit.

PAPAYA SALAD


4 cups ripe papaya cut in
cubes
6 teaspoons finely chopped
onion
1 teaspoon salt


4 cup cooked salad dress-
ing or mayonnaise well
seasoned
1 cup finely chopped celery


Cut papaya into cubes, add the chopped onion and
celery. Chill, serve on lettuce leaves and garnish with
mayonnaise.
PAPAYA CITRUS SALAD


2 cups ripe papaya peeled
and cut in inch slices
1 cup grapefruit sections,
canned or fresh
1 Green pepper cut small
2 young onions, cut fine
1 cup orange sections


4 stalks celery, cut fine
1/2 cup carrots, cut fine
/2 cup thinly sliced kum-
quats
Well seasoned, snappy
French dressing
Crisp lettuce









DEPARTMENT OF AGRICULTURE


Blend all ingredients together and place on cold, crisp
lettuce. Season with the French dressing and serve with
crisp crackers or cheese wafers.

BAKED PAPAYA
1 small firm ripe or half- 1 tablespoon butter
ripe papaya 3/4 teaspoon salt
2 tablespoons lemon juice
Pare and cut papaya lengthwise into six pieces, remove
seeds. Sprinkle with salt, lemon juice and butter. Place
in a baking pan, add enough water to cover bottom of pan
to prevent burning and bake in a moderate oven (350 de-
grees Fahrenheit) for 35 minutes. Serve immediately after
removing from the oven. This may be used in place of a
vegetable.
PAPAYA SAUCE CAKE


1/4 cup fat
1 cup sugar
1 egg
11/ teaspoons baking pow-
der
1/2 teaspoon salt
1/3 teaspoon ground
cinnamon
1/3 teaspoon grated nutmeg


1/4 teaspoon ground ginger
11/2 cups flour
2 teaspoons lemon juice
1/ cup seedless raisins if
desired
3 tablespoons water
cup diced ripe papaya


Stew the papaya and water together until a soft, thick,
smooth sauce is obtained. Cream fat, add sugar, mix well,
and add beaten egg. Sift salt, baking powder, spices and
flour together. Add cooled papaya sauce and dry ingred-
ients alternately to egg mixture. Fold in lemon juice and
raisins; then pour into an oiled loaf-cake pan and bake in
a moderate oven (350 degrees Fahrenheit) for 50 to 60 min-
utes.
PAPAYA PIE


2 cups strained papaya
pulp
1 tablespoon butter
2 egg yolks
1/4 cup sugar
1 teaspoon ground ginger


1 teaspoon ground cinna-
mon
1/4 teaspoon ground nutmeg
1 teaspoon salt
2 tablespoons lemon juice
(may be omitted)









THE PAPAYA-A FRUIT


Melt butter, add cooked papaya pulp, egg yolks, sugar,
spices and lemon juice. Pour into a baked pie shell. Bake
for 45 minutes or until firm in moderate oven (325 degrees
Fahrenheit).
PAPAYA MILK SHERBET
11/ cups ripe papaya pulp 1/2 cup orange juice
3 tablespoons lemon juice 11/2 cups milk
1 cup sugar
Press papaya pulp through a coarse sieve and combine
with fruit juice. Dissolve sugar in milk, add fruit mixture
gradually to milk, and freeze in an ice cream freezer, using
8 parts of ice to 1 part of ice cream salt. Ice cream may be
made by substituting thin cream for milk.

RIPE PAPAYA JAM
6 cups ripe papaya pulp 1/ cup lemon juice
5 cups sugar
Press ripe papaya through a coarse sieve before meas-
uring. Boil briskly for 20 minutes, or until thick enough
for jam. Add lemon juice and sugar and continue boiling.
Stir frequently in order to prevent scorching or until of de-
sired consistency. Pour into hot, sterile jars and seal im-
mediately.
PAPAYA MARMALADE
10 cups sliced firm ripe Grated rind of 1 orange
papaya and 2 lemons
1 cup fresh shredded 3 tablespoons grated green
pineapple ginger root (if flavor is
% cup orange juice liked)
1/2 cup lemon juice 8 cups sugar

Combine all ingredients except sugar and boil for about
30 minutes or until somewhat thick. Add sugar, and cook
S together until clear and of consistency desired. Stir fre-
quently to prevent burning and when as thick as desired,
pour into hot, sterilized jars and seal immediately. Store
in cool, dry, dark place.








58 DEPARTMENT OF AGRICULTURE

PAPAYA PRESERVE
Use sound, full-ripe fruit. Peel and cut in shapely, uni-
form pieces. Remove seed or not, as preferred. Weigh and
for every pound of papaya add one pound of sugar. Sprinkle
over fruit and allow to stand overnight until sugar is dis-
solved. If enough liquid is not drawn from fruit to cover,
it may be necessary to add a small amount of water.

Place over heat, bring to boil and boil 10 minutes or
until fruit is clear. Cover tightly and let stand overnight.
Bring again to boil and boil until syrup is thick. Fruit must
be kept covered with syrup at all times.

Pack in hot, sterile jars and cover with the hot syrup.
Seal at once.

Lime juice, calamondin or other citrus juices may be
added if desired, but many prefer only the mild, distinctive
flavor of the papaya. The syrup is golden in color and most
delicious in flavor.

SWEET SPICED PAPAYA
Prepare the fruit and cook as for preserves. When fruit
is clear and syrup thick and heavy, drain from fruit and
add one-half cup of best vinegar to each pint of syrup, and
whole spices as follows: 1 tablespoon whole cinnamon, 1
teaspoon each of cloves and all-spice tied loosely in a bag
and lightly pounded. Boil 5 minutes then add to papaya and
cook another 5 minutes.

Let stand over night. Reheat and transfer to hot, ster-
ile jars and seal at once.








THE PAPAYA-A FRUIT 59




[ndex

The Papaya 3
General description and appearance 3
Origin -.... 4
Discovery and dissemination 5

Botanical Classification -. 5
Domestic and wild forms 6

Other Caricas 7

Breeding 8
Budding and grafting 8
Problems of unisexual phases 9
Pollen distribution 9
Insect agents 9
Orchard breeding work 10
Problems with hermaphroditic types 11
Irregular blossom, habits of 14

Papaya Culture - 19
Climatic necessities 19
Possible territories 22

Soil Demands 23
Physical characters-- 23
Chemical characters 24

Moisture Requirements 24
Floodable lands 25
Irrigation 25

Plant Foods ------------ 26
Composts .--- -------------- 29
Total needs -----------30

Frost Protection --- --30
Elevation ----..- 30








DEPARTMENT OF AGRICULTURE


Lakes --- -- . 31
Irrigation ....... 31

Artificial Heat ... 32
Woods fires 32
Heaters .. ... -- -32
Weather service -- -- -- 33

Fruits ..- ....... ...... ....... ...... 33
Palatable or not --.. ................. 33
Size, shape, texture -- ----. 34

Planting -... - -.-- -...... 36
Seed .. - .. .. 36
Soils, potting and flats . 36
Field setting, Spring and Fall 37

Pest and Disease Control ........ 39
Leaf Spot -- -..-- -. -. -. .. 39
Anthracnose of fruit .. ...... 40

Papaya Fruit Fly -- ....... 40
Description 40
Control -- .-... ... .. 41

W hite Fly ............ 42

Horn Worm ----- -.. 43

Papaya Products .----...--.- ...... .... 43
Present status ..----.--- ................ .... 44
Possibilities .... 47

Digestive Factors .. ....--- .. 48
Latex, occurrence ------ --- 48
Misunderstandings -- ----48

Papaya Sales .....- .... 50

Picking, Packing and Shipping ... 52

Shipping Character --- --53


Recipes




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