O/f Fruit Suitable for South Florida
SCOTT II. STAMBAUGH
[ he 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 attached 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 conditions. They may be almost any size from that of a walnut to twenty-eight pounds. The shapes run from almost perfectly spherical through eggshape, through pearshape or even almost perfectly cylindrical. The flesh is like that of a
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 iA 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 conditions. 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-
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 clone 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-live 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.
The fruit we call the papaya has generally been classified in all of its varietal forms under the single species carica
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 territor}' where the wild form existed naturally or where the wild form could establish 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 wild papaya as a matter of sex type is always unisexual. 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 unisexual character. The Core Type should in no way be confused 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 occurrence 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 erroneous notion. The Core type is of no Mendelian significance any more than the occurrence of borderline sex manifestations 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.
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
have failed under Florida conditions. Then too the Mountain 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 pentagona, 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.
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 pentagona. 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 possible information that can be had in the way of scientific facts will not be too much. This is particularly true because a lot of unfortunate confusion has arisen as to the main basic facts of papaya breeding. This has been largely
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. Unfortunately 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 commercial 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 commercially useful type of papaya.
This matter of simple selection for fruit and plant characters 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 territory 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 arrangements. 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 characters 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
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 tropical 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 distribution 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 characters and are usually quite homozygous for those characters. It should be remembered however that regardless of how uniform they are, if they are unisexual, that is, requiring 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 attractive 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 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 another usually results in injury of the flower parts. Latex exudes and the pollen is digested by the active enzyme contained 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
Typical plant, Blue-Solo perfect flowered, lirst hybrid generation on rich permanently moist hammock soil at Vero Bench. This illustrates the capacity of the papaya to lake 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.
Specimen plant of Blue-Soio 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.
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 hermaphroditic and set fruit. This irregularity of flower behavior 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 character 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
in the flowers. This results in an irregularity of fruit production 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 cylindrical. 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 hermaphroditism. 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 introduction 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 experimentation for each new varietal form adapted.
There is a considerable family of typically hermaphroditic 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 problems 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
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 before giving them up.
The geographical origin of the typically hermaphroditic strains of papaya throws considerable light on their behavior. They come from a definitely circumscribed territory, 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 significent. 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 considerable 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 then-source.
Seed taken just as it is introduced from a known hermaphroditic 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 apparently 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
seems evident that the percentage of hermaphroditic seedlings expresses the degree of nature close fertilization and the percentage of unisexual seedlings produced is an expression of the degree of cross fertilization. It is significent 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 hermaphroditism in 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 somewhat 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 operator 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 consideration 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.
It may not be theoretically sound genetics but it has been the practice of this operator to consider that once ail 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 seedlings will be hemaphroditic, less than 1 per cent male, and the residue females.
This process is somewhat involved and of course necessitates 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 homozygous 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 tendency to stay in line.
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 attention 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 restricted 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 temperature 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 temperatures 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 variation 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
Specimen plant old type big Blue-Stem. Unisexual female, grown on scarified Oolite Limestone.
Planting Of Blue-Solo at 18 months of age, Average height of plant 20 feet, Spacing 10 feel 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,
no papaya variety under any situation will stand temperatures of 32 or below.
The papaya has been grown in protected spots from Key West to St. Augustine and all across the peninsula in Florida. 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 problem 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 sunshine and temperature index for the winter season. This would prevent the ripening of the fruit of the papaya during 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 economics 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 suitability for the growing of papaya. By the same token he
should not neglect the matter of economics and a great many factors other than weather enter into the matter of economics.
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 quantities 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 produced very economically on a soil that is almost pure Calcium 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 saturation 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 hax*dpan. Where these soils can be defended from water and frost, they seem to be entirely 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 doubtful value. The plants grow off rapidly and make tremendous 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 alluvial soils of the Rio Grande Valley of Texas.
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 adversely to the matter of pH alone. It is evident, however, that this plant requires larger percentages of organic material in the soil makeup and a greater plant food concentration 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 application 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 application 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 decomposition of vegetable debris and these soils are actually composed of preserved vegetation in a very stable and unavailable 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.
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-
nitcly limited by allowing the crop to bo subjected to a long drouth without irrigation. Where the texture of the soil is such that it can, the papaya develops a truly enormous 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 stagnant 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 condition. 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 expensive crop when judged from the standpoint of fixed overhead charges per acre. The total yield of papaya on a given acre of land can usually be more than doubled by systematic irrigation. It is hardly worth while, therefore, to attempt papaya growing commercially without irrigation. The papaya crop, once the plants are established and growing 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.
All sorts of irrigation systems have been tried for the growing of papaya in Florida. The overhead system of irrigation 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 papaya, 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 gallons 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 continuous.
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 capacity of the plant to use food is reached with all three of
Specimen plant of perfect flowered character. Old type big Blue-Stem, grown on scarified Oolite Limestone in Dade County under overhead irrigation. Ten tons of waterweed compost used in making hills; 4>,4 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 illustrates the adaptability of this plant to widely different physical soil conditions.
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>'2 feet. This indicates the capacity of this plant for vegetative growth where moisture and plant food are not limited by the character of the soil or the physical
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 program. 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 manures to weeds and grass for each acre. It should, however, contain enough manures to start decomposition when sprinkled. Chemical plant foods for a year's fertilization of the papaya field can then be added to the compost. The moisture 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 under 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 applications.
Best results can be had by spading in a certain amount of the compost before planting and then applying in furrows a little farther from the hill each time in successive applications as the plants grow and their root systems enlarge.
In contemplating the planting of papaya the grower should bear in mind that each acre is going to take the
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 fertilized, 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 matter 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 ripeness, 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 condition. Fertilization must be carried on at the same rale as long as the plant is in bearing condition if maximum results are to be obtained.
There is no such thing in Florida as a totally frost free location where a susceptible plant like the papaya is under consideration. The site for the papaya plantation then should be selected so as to require a minimum of frost protection. There are a number of factors in the matter of natural frost protection that should be taken into consideration in determining the suitability of each particular piece of land.
The matter of air drainage due to elevation of the specific land under consideration and the contour of the surrounding 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 except 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
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 tremendous help if the territory all around is low and a considerable 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 question are important helps in the matter of frost protection. Take for instance, a lake approximately round and a mile or 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 protection, 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 service 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 difficulty seems to be that down to 32 degrees F. overhead irrigation 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 protecton 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.
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 capable 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 considerably 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 heater 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 purchased, 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.
Strict attention to the daily weather map on the part of the grower and to the daily forecasts of the frost protection 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 changing.
There are many varietal forms of carica papaya growing 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 definite fact that the vast majority of the varietal forms of papaya 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 distasteful 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 unpleasant 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 introduced to Florida are free of this odor and flavor. By the
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 selection 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 IBs. 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 factory.
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 package 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
of flesh bears particularly on the matter of papaya products. Texture is of course also important in the matter of palatability. 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 character of fruit for all purposes. Green fruit of such character 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, results 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 supplied 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 sugar 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 other specific characters. Fortunately this strain can be identified 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
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.
It should be borne in mind that the growing of papaya 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 operations 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 diminished 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 greenhouse 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 surface 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.
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 %" 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 potting operations to be done thereafter should be done with soil of loose coarse texture, containing plenty of organic material, little or no chemical fertilizer, and that has been carefully 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 distressed 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.
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 cany 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 watered 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 hurricane season with a full crop of fruit on them. If they are blown out, they are blown out completely and without having 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 perfect flowered plants having desired characters. Late in August the plants will be 2y2' to 3' high and from %" to VA" 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.
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 resorted 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 21/2" across. In the bottom of this saucer 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 2K>' 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 chemical 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 culture 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 curative work.
There are only two diseases of any importance affecting 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
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 character of large quantities of fruit.
Both the leaf spot and anthracnose can be controlled by regular application of 3-3-0 bordeaux. It is recommended 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
This fly has been held over the heads of papaya growers as something of a bogey. As a matter of strict fact the control 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 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 extended 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 attempting 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 yellow 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 coincides 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.
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 appeared 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 however probably a grand thing for the budding papaya industry 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 eliminate 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 containing contact poisons. The white fly is not difficult to control if control measures are started early. The first
time a few insects are detected, contact poisons can be added 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 whatever 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 destroyed 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 of 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.
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.
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 seasons 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 northern 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 manufacture of a considerable list of papaya products are already known. There is considerable knowledge of just how salable 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 several 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
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 crystallized 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 manufacturers have different ideas as to how fast to raise the percentage 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 barrels, 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 below the surface of the pickle. Any pieces that come anywhere near the surface will become soft and slimy and cannot 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, drained 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
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 preserves. 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 digestive 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 purpose; some of them by people who have none of these qualifications. All kinds of processes have been resorted to. In some cases the papaya, skin, seeds and all was put through
a squeezing process to give up a filtered juice and the pomace used for other purposes. These efforts to express juice from the papaya have all been unfortunate. Little results from such a process but dirty water, the reason being that the flavors and sugars are tied up in chemical combination 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 character 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 flavor to be sold as a drink. There seems to be some possibility of success along this line and staying within the regulations 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 consistency 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 papaya, 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 papaya and for that reason is entitled to sell as health ice cream.
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.
The fresh fruit of carica papaya when full maturity has been reached but the fruit is still unripe yields a considerable 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 stomach as does animal pepsin, in that it digests comparatively 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 gradually 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 in the lack of the capacity of the individual stomach to digest proteins. The use of the dried latex in medicines for indigestion of all sorts has increased to enormous proportions in the course of the last 50 or 60 years. The use of this papain either as fresh fruit or as a drug is too well established and too thoroughly understood to be even subject to question.
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 character 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 native to the seed of the papaya. This oil is not an aid to di-
A display of papaya in a fancy grocer's shop in San Antonio, Texas. This display is of the Blue-Solo variety. Fruit of tiic second hybrid generation. This fruit was wrapped in ceiiophane ana packed in fruit lugs bedded in excelsior, The packages held three, five, six or eight me.ons, 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.
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 greatest 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 beneath the skin of the papaya the eggs are digested and no larvae hatch out. This is true up to the point of decomposition of the ripe fruit. Once the flesh of the full ripe papaya commences to decompose and break down the enzyme has entirely disappeared and such overripe fruit can actually 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 subjected to ordinary cooking temperatures loses the activity of the enzyme.
The papaya will of course be grown for profit if at all. This matter of where and how and what kind of papaya are salable is probably more important to the prospective 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 papaya have existed in Florida of more or less edible character ever since white men have been here. It is practically impossible at this point to avoid the remark that they were mostly less edible.
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 medicine because of this fact regardless of how nasty it may taste and smell. Vast quantities of papaya arc 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 unquestionably gives the papaya a tremendous sales advantage. 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 papaya enterprise is based on seed or plant stock whose ancestry 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 commercially 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-
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 handling that would fit the general crop. The following recommendations 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
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 probably 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 thoretical. 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 standing on end.
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 unripe 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
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 grower will have to learn to know the ripening peculiarities of his particular papaya.
I he 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.
4 cups ripe papaya cut in cubes
6 teaspoons finely chopped
onion 1 teaspoon salt
;4 cup cooked salad dressing 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 Vz cup carrots, cut fine Vz cup thinly sliced kum-quats
Well seasoned, snappy French dressing Crisp lettuce
Blend all ingredients together and place on cold, crisp lettuce. Season with the French dressing and serve with crisp crackers or cheese wafers.
1 small firm ripe or half- 1 tablespoon butter ripe papaya % 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 degrees Fahrenheit) for 35 minutes. Serve immediately after removing from the oven. This may be used in place of a vegetable.
PAPAYA SAUCE CAKE
Ya cup fat Ya teaspoon ground ginger
1 cup sugar IY2 cups flour
1 egg 2 teaspoons lemon juice \Yz teaspoons baking pow- % cup seedless raisins if
Yi teaspoon salt 3 tablespoons water
1/3 teaspoon ground cup diced ripe papaya
cinnamon 1/3 teaspoon grated nutmeg
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 ingredients 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 minutes.
2 cups strained papaya 1 teaspoon ground cinna-pulp mon
1 tablespoon butter Ya teaspoon ground nutmeg
2 egg yolks 1 teaspoon salt
Ya cup sugar 2 tablespoons lemon juice
1 teaspoon ground ginger (may be omitted)
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
1% cups ripe papaya pulp Vz cup orange juice 3 tablespoons lemon juice \lk 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 Vz cup lemon juice
5 cups sugar
Press ripe papaya through a coarse sieve before measuring. 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 desired consistency. Pour into hot. sterile jars and seal immediately.
10 cups sliced firm ripe
papaya 1 cup fresh shredded
pineapple xk cup orange juice Vz cup lemon juice
Grated rind of 1 orange
and 2 lemons 3 tablespoons grated green
ginger root (if flavor is
liked) 8 cups sugar
Combine all ingredients except sugar and boil for about 30 minutes or until somewhat thick. Add sugar, and cook together until clear and of consistency desired. Stir frequently to prevent burning and when as thick as desired, pour into hot, sterilized jars and seal immediately. Store in cool, dry, dark place.
Use sound, full-ripe fruit. Peel and cut in shapely, uniform 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 dissolved. 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, sterile jars and seal at once.
The Papaya....................---------..................... ............------------ 3
General description and appearance ........ 3
Origin ......_.......... -........-......-.......-.........-.......-................ 4
Discovery and dissemination..........................-------- 5
Botanical Classification ...............-.......... .............. 5
Domestic and wild forms ......-............---------- 6
Other Caricas..............................-.......-........-....... ?
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....................-...........-..... -------......... 2o
Plant Foods........-...................-.......................................-......- 26
Composts -.....................-.......................-.....-......---------....... 29
Total needs.......................'.:____________......--------............. 30
Frost Protection.....................-------..........................................-- 30
60 DEPARTMENT OF AGRICULTURE
Artificial Heat 32
Woods fires 32
Weather service 33
Fruits ...................... 33
Palatable or not ....._................. 33
Size, shape, texture 34
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
White Fly 42
Horn Worm 43
Papaya Products __________........ ._....... 43
Present status ......._....... 44
Digestive Factors 48
Latex, occurrence 48
Misunderstandings ..... 48
Papaya Sales ...... ................_....... 50
Picking. Packing and Shipping 52
Shipping Character 53