Papaya Production

Papaya is a well known plant in the Philippines, a very common food item in the local markets which is a good source of Vitamin A, B, and C. Its productive life is about 3 ½ years and the plant's luscious fruits are available throughout the year.

Papaya is grown for different purposes, could be for various food preparation, for industrial and for medicinal uses. When green it is use as a vegetable, it is being cooked or processed into pickles. The ripe fruit is eaten as a breakfast fruit, ingredient in fruit cocktail or salads, in preserves, sauces and pies or as an inviting drink. The enzyme papain which is obtained from the latex is used as a meat tenderizer, in beer processing, softening of woolens, manufacture of toothpaste and nowadays it is usually the main ingredient in many whitening products like soap and lotion . The leaves when properly flavored can be made into cigarette.

Because of these uses, papaya has a great economic potential and since it can be easily grown even in home yard gardens, this could be a profitable enterprise.

I. BOTANICAL DESCRIPTION

Papaya also known as pawpaw, kapayas in Visaya and Tayapas in Bikol is a giant herb which reaches 10m in height and is widely distributed in the tropics. The papaya usually has unbranched trunk which bears prominent leaf scars. At the top of the trunk are large, deeply-lobed leaves with long stalks. The male and female plants should together if the species is to produce fruits and seeds. In the course of frequent cross pollination, it is inevitable that the pollen of other varieties should find its way to the stigma of the flower of the female plant, the only one that bears fruit. Hence, in the cultivation of such plants it is desirable to limit or reduce the number of male plants in a group to conserve the desired variety.

Papaya may be grouped into 3 sex types according to the flowers they produce. The 3 types are female, male and hermaphrodite. The white male and female flowers are normally found in separate plants (Dioeciously).

Male papaya trees produces long, pendulous and many flowered inflorescence throughout the year but occasionally bear flowers which are capable of producing fruits if fertilized.

The female trees bear female flowers only which are sessile. Its large flowers, about 5cm long, are borne at the leaf axils close to the stem and occur singly or in small clusters. The flowers posses functional ovaries but lack stamens and thus rely on an outside source of pollen for fruit set to occur. Female flowers are several times than the male. Female flowers are entirely dependent upon the male or hermaphrodite flowers for pollination and fruit setting. Normally female flowers produce rounded fruits that bear 5 distinct scars which are arranged in circular fashion at the base of the fruit.

The hermaphrodite flowers, sometimes referred to as bisexual flowers, contain both the essential organs of the female and male flowers. Most of the hermaphrodite flowers are unstable under field conditions, being easily affected by the changes of the environmental conditions. Hermaphrodite flowers are highly seasonal but some produce fruits throughout the year. There are several variants of hermaphrodite flowers. Some of these produce only two stamens while others produce as many as 10 stamens. Fruit produced by hermaphrodite flowers are elongated.

Under favorable conditions, hermaphrodite plants produce flowers with female like tendencies while unfavorable conditions favor the production of flowers with male- like tendencies. This is why, during summer when growing conditions are unfavorable, many of the hermaphrodite papaya trees particularly the summer steriles do not bear any fruit.

The only reliable means of determining the sex of the plant is to wait until it has borne its flowers which usually come 4 to 6 months after planting.

II. DIFFERENT VARIETIES/ CULTIVARS

Many varieties of papaya have been introduced in the Philippines. Majority have lost their distinct varietal characteristics mainly because they are commercially propagated by seeds.

In terms of selection, the principal factor to consider is the consumers’ preference. Local consumers and growers prefer large-fruited papayas.

1. Cavite Special- is a popular semi-dwarf type that blooms 6 to 8 months after planting. The fruit weighs from 3 to 5 kilos each and mainly eaten fresh.

2. Sunrise Solo - is a new improved high quality selection with reddish orange flesh, each fruit weighing half a kilo.

3. Waimanalo - is high quality variety with orange yellow flesh, each fruit weighing from one half to one kilo

4. Sinta - is the first Philippine- bred hybrid papaya, semi dwarf, profile, sweet and fleshy and weighs 1.2 – 2.0 kg/fruit. Prolific producer of papaya, excellent fruit quality, medium resistance and most active variety.

III. SOIL AND CLIMATIC REQUIREMENTS

Soil Requirements

Papaya trees are not selective as to their soil requirements for as long as surface and internal drainage are good. Papaya thrives best in light, well-drained soils rich in organic matter. Clay soils which lack good aeration are not good for papaya.

Low lying land where water accumulates and stands after heavy rains should not be grown to papaya. Water logging is very harmful and imperfect drainage encourages root and stem rots. Standing water around the roots for even a day is likely to kill the plant. If not killed by excess water, it loses its vigor and recuperates very slowly. Prolonged rainy periods may result in premature shredding of the lower leaves, yellowing of young leaves, thin and tall stems, and reduced yields.

The soil must have a good supply of available nutrients. Papaya can tolerate soils with pH ranging from 5.8 to 7.0. For best results, the spoil should have a soil pH about 6.0 to 6.5.

Climatic Requirements

Papaya prefers a warm climate with abundant rainfall or irrigation. An average daily temperature can be tolerated provided the soil has adequate moisture and relative humidity. Cool weather reduces growth and yield and has an unfavorable effect on fruit flavor.

A minimum annual rainfall of 1200 mm is sufficient provided soil conditions are favorable and water conservation practices are employed. Rainfall should be well distributed throughout the entire growing season.

The plants are found from sea level up to 2100 but grow best at lower altitudes. Commercial plantings for high grade fruit are found below an altitude of 1000m. For papaya production, papaya should be grown at altitudes below 900m. Since the flow of latex above this altitude becomes progressively slow.

IV. PROPAGATION AND PLANTING

A. Propagation

Propagation by seeds is the most practical method. They can be sown in flats of soil, seedbeds or in small containers and allowed to germinate in a partially shade place. Sterilized soil should be used to avoid damping-off and nematode infestation. In the seedbeds, the seeds should be placed in shallow furrows and covered with thin layer soil. Germination takes place in 3 to 4 weeks. When 2 to 3 true leaves have appeared, transfer seedlings into small containers. Polyethylene bags, tin cans or any other suitable containers can be used. The plants should be watered only when the soil appears dry since excessive moisture induces the growth and spread of damping-off fungi.

The seed may also be sown directly in small containers, 3 to 4 seeds per container. As soon as the seedlings are 15 to 20 cm tall or develop 3 to 4 leaves, transplant them into the field. It is necessary to transfer the seedlings before reaching a height over 30cm. Care should be taken not to disturb the roots.

Papaya plants may also be started by directly sowing the seeds to the field. At least 8 seeds are placed in a planting hole and covered with about 1 cm of soil. After emergence, some of seedlings should be removed, leaving 4 most vigorous ones. When they are 30cm high, thin seedlings to 3 and allow them to grow until they produce flowers and their sex can be determined. As soon as the sex is determined destroy the two and leave only one vigorous female plant to bear fruits.

Seeds can be stored for up to six years at 5⁰C (41⁰F) in sealed moisture proof bags without losing viability. Best seeds are from controlled pollination between superior trees. Papaya trees can also be produced by budding by invitro micro propagation and by cuttings.

B. Land Preparation

Land preparation for papaya is similar to other upland crops. First clear the fields, then plow and harrow alternately about two to three times to kill weeds and provide good internal drainage. If papayas are to be planted in places where there are distinct wet and dry seasons, land preparation should be properly timed in such a manner that the land is ready for planting when the rainy season begins.

C. Marking the Field and Distance of Planting

Layout the land so planting and subsequent operations like weeding , fertilizer application, pest and disease control and harvesting are facilitated. On flat to gently rolling land, the square, triangular or rectangular system of planting are recommended. On rolling land, planting on contour is highly recommended to minimize soil erosion.

Distance of planting depends upon the variety, soil fertility and management practices to be followed. The common practice of the farmers is to plant papaya trees as close as 3 meters apart and as wide as 5 meters apart. Wider spacing of 4 to 5 meters is commonly used in areas where the soil is rich or where the farmers practice intercropping.

D. Preparation of Planting Materials

Remove the gelatinous material that covers the seeds. To clean the seeds simply macerate them in sand or in a piece of cloth after gathering them from a slice papaya fruit. Once macerated, wash thoroughly in clean water, then dry. When conditions are warm, do not sundry the seeds, but rather air dry them. If planted in suitable conditions, fresh papaya seeds will start germinating in 10 to 15 days after sowing.

E. Planting and Transplanting

When papayas are directly seeded (3 to 5 seeds) they are immediately planted in the field after the land is laid out. If seed germination is high, more than 50% of the seeds planted will germinate. If the seedlings are released in the seedbed, transplanting time should be when the seedlings are about 15-20 cm high. Water them regularly until they are established in the field. Carefully remove the seedlings from the nursery beds before transplanting. Avoid serious root injuries.

F. Thinning the Plants

Thin papaya seedlings in the field 4 to 6 weeks after emergence. Leave only 3 of the strongest seedlings in each hole. Save plants that are spaced for enough from one another to allow minimum completion for sunlight and nutrients.

The second and final thinning in the field should be done as soon as flowers appear. This is usually 4 to 6 months after seed germination. At this stage, leave one tree seedling per planting hole. In plantation where female trees are grown, some pollinating trees of either male or hermaphrodite forms should be preserved during the thinning process. Allow one male plant to grow for 15 to 20 female trees for pollination process.

V. CARE OF PAPAYA PLANTATION

A. Establishment of Windbreaks

Windbreaks are necessary in areas where strong winds prevail. Local materials used as windbreaks are ipil-ipil and madre cacao . The distance between windbreaks varies with location. where wind blows horizontally across the plantation, a common rule of thumb is to space windbreaks at a distance of 20-30 times the height of windbreak trees where winds come in different direction and angles, it is necessary to have windbreaks half as close.

B. Fertilization

Factors such as soil types, rainfall, locations, cultural practices and age of plant influence fertilization practices. Start fertilizing when seeds are planted or when seedlings are transplanted in the field, mix a handful (5 to 10gms) of complete fertilizer (14-14-14) with the soil at the bottom of the hole before planting. As papaya seedlings grow larger, more fertilizer is applied.

During the first vegetative growth of 6 months after planting, a continuous supply of available nitrogen is necessary to maintain healthy papaya plants.

Basal application of complete fertilizer has proved beneficial to many papaya growers in the country. In areas where potassium is low, the application of complete fertilizer with NPK ratio of 2:1:2 or 2:1:3 has proved highly profitable.

Potassium becomes of particular importance after the flowering stage. Young plants should be provided with readily available phosphorus.

Guide for papaya fertilization in the Philippines.

1. Apply 60 grams of ammonium sulfate as soon as plants are well established and show new growth.

2. Apply the same amount of intervals of 6 weeks until plants are one year old.

3. Thereafter, apply 22 grams of ammonium sulfate per plant every 3 months.

4. Apply 450 grams super phosphate per plant at the start of rainy season every year.

5. In potassium deficient soils, complete fertilizer with ratio 2:1:2 or 2:1:3 is recommended.

C. Weed Control

Weeds can be controlled by mechanical, shallow cultivation and chemical means. Hand weed when papaya plants are less than 2 ½ meters high. Always keep one meter around trunk free from weeds.

The most common practice to control weeds in papaya plantation is shallow cultivation. shallow cultivation is necessary because it does not destroy many roots of the plants that are growing near the surface of the soil.

In large commercial papaya plantation, weed control is done using herbicides. Spray post. Emergence herbicides such as Paraquat of gramoxene plus a surfactant, at intervals between sprays 5 to 6 weeks. Since papaya seedlings are very sensitive to chemical sprays, remove close to seedlings manually.

D. Irrrigation

An adequate moisture supply is required for good growth and yield. Papaya requires plenty of water. Newly established plants can tolerate some dry weather but when flowering starts a week of dry weather may cause the flowers to drop. Older crops are more resistant to drought because of their rate of vegetative growth and more extensive root system, but they will not produce high yields when water is not sufficient.

Plants should be irrigated during dry months since water stress causes growth retardation, flower abortion and dropping of young fruits.

Practice mulching during the dry season. A mulch of rice hull, saw dust or rice straw at a distance of 20 to 60 cm from the plants may be recommended.

E. Intercropping

Papaya can be grown as intercrops with coconuts, coffee, pineapple or assorted vegetables. Intercropping with papaya increases total farm income and reduced weeding expenses. It is important to provide fertilizer requirement of the intercrop.

VI. COMMON DISEASES AND PESTS OF PAPAYA AND THEIR CONTROL

A. Diseases

1. Phytophtora Blight / Rot

-caused by Phytophtora Palmivora . Common symptoms are found on stems and fruits. Small, water-soaked, discolored spots may occur anywhere on the stem, around the fruit or leaf scars especially during fruit production. These infected areas enlarge and often completely encircle stems of young trees green fruits are resistant to infection but can invaded through the wound or through the peduncle from the stem cankers, progresses, turn dark brown, become mummified and fall to the ground. Mummified fruits become reservoir for fungus and source of infection.

Control: Remove rotting fruits the tree as trees serve as reservoir of spores from fungal mass which is carried by rain or wind to healthy parts of plants. These spores may infect non-injured leaf tissues, stems or fruit, good-drainage conditions reduce infection and use of protectant spray such as copper sulfate or Dithane M-45 fungicides limit extent of injury.

2. Anthracnose

-caused by Collectrichum gloeosporiodes Penz. A fungus found attacking many plants in tropical areas. It affects both plants in the field and the fruits at harvested. A first symptom is usually a small, round, water-soaked area on ripening portion of the fruit. As fruit ripens, these spots enlarge rapidly, forming circular, slightly sunken lesions; these enlarge up to 2 inches in diameter as fruit matures. Fungus frequently produces large, light orange or pink masses of spores in the center of the lesions. Sometimes, spores are produced in concentric rings similar to a bulks eye. In addition to produce this surface damage, the fungus also advances into the fruit.

Occasionally, green portions of the papaya become affected. Disease first appears as a small, water soaked lesion. Soon after the fungus penetrates the fruit, latex comes out in sticky mound of horns. These lesions enlarge to ½ inch in diameter as fruit remains green and eventually plant dies. Infected petioles may act as a source of inoculums for infection of fruit.

Control: Thorough spray program. In many rainy areas with high temperature, spray Dithane M-45 at 7 to 10 days intervals. Copper-based fungicides also provide good controls.

3. Papaya Mosaic

-initially leaves develop rugged appearance. Undersides of leaves show thin, irregular, dark-green lines etching the borders of cleared area along the veins. Younger leaves of crown are generally stunted and severely chlorotic with veins building transparent oily areas are scattered over leaf or long leaf veins. In mature leaves, chlorotic patterns are accompanied by numerous small kinds ranging from transparent yellow to tan yellow. In several affected areas, defoliation progress upward until only a small tuft of leaves remain at the crown. Stems of infected plant show pinpoint-sized, water-soaked spots may develop into linear or concentric ring patterns which become longer and more intense in color. This is generally transmitted by green peach aphid, Myzuz persicae .

Control: The only satisfactory way of controlling is by destroying source of the virus. Strict rouging program should also be followed.

• Spray all infected trees with insecticide to kill aphid carriers.

• Cut all infected trees with insecticide to kill aphid carriers.

• Cut all infected trees and remove them growing trees and other cucurbit plants.

• Avoid nearby cultivars of cucurbits plants

• Control aphids with pesticides since they are disease carriers.

4. Damping-off of seed

The major causes of fungi including Phythium aphanidermatum (Edson) Fitz; Phythium ulitmun Trow; Phytophthora parasitica, Dastur; Rhizocphthora palmivores. Butler and Rhizoctonia sp . These fungi are all found in most soils. Damping-off is common in young seedlings wherein the tissues at the soil line become rotten due to the growth of one or more of the causal organisms.

5. Stem-End Rot

Post harvest disease caused by fungi Aschochyta sp . and Phytophthora parasitica . Infected fruits become shriveled and dark brown. They ultimately become brownish-black, light in weight and mummified.

Control: Infected fruits should immediately be removed from the field. Protectant sprays with Dithane M-45 may also be used to control the disease.

6. Rhizopus Fruit Root

-caused by Rhizopus Stolonifer (Enrehb. Ex. Fr.). This fungus only invades injured mature fruits. Infected fruits produce a soft watery rot while the fungus continues to grow in the infected tissues. High humidity favors the production of masses of visible black sporangia.

Caution should be observed in harvesting and packing operation so as not to bruise the fruits. Prompt removal and proper disposal rotten fruits in the packing sheds will help reduce the source of spores capable of starting new infections.

7. Root- Knot Nematodes

-caused by several species of Meloidogyne . Roots are only parts attacked. The feedings of the nematodes result in the production of root galls of various sites. Severe infestation brings about subsequent root systems.

Control: Soils that are heavily infected with root knot nematodes and intended for replanting to papaya can be plowed thoroughly and allowed adequate time to lay idle for the decomposition of heavily-galed roots.

B. PESTS

• MITES

-colonized on different parts of the plants and feed on plant, causing premature leaf drop, reduce tree vigor and produce external blemishes on fruit. They puncture plant tissues with their needle-like mouth parts and feed on tissue juices. Some multiply rapidly throughout the year and cause widespread damage in a very short time.

Control: Control mites by sulfur dusting. Spray malathion at rates recommended by manufacturers.

Fruit Fly/ Oriental Fruit Fly

-Dacus dorsalis Hendel, infests fruits which are allowed to ripen in the tree beyond recommended picking stage. Fruits harvested in the mature green stage are not infested due to the milky substance they exude when fruit is punctured.

Control: Sanitation is important. Harvesting the fruits during the mature-green stage. Destroy all dropped and premature ripe fruits and suspected of being infested to prevent larvae from developing into adults flies.

VII HARVESTING AND HANDLING

Harvesting is a simple operation when papaya trees are short and the fruit can be reached by hands. The first harvesting starts on the 7^th to 8^th month after planting. Pick all fruits showing a tinge of yellow at apical end.

Under local conditions and if well managed, you can harvest from 3-8 fruits from one tree per month at two weeks interval. Usually, the highest yield is obtained during the first year of fruiting.

The most common harvesting aid is the bamboo pole, some pickers use light step ladders. Harvesting is done with the use of ladder when papaya trees grow older. It is tedious, time consuming and costly method of harvesting. Farmers in Cavite use a long pole to strike the apical end of the papaya fruit to detach it from the tree while the fruit is caught by hand.

Place harvested fruits in picking bags, galvanized containers or pails, Allow fruits to mature more fully to develop the better flavor. However, these shorten shelf life and make them more susceptible to fruit fly infestation. These peduncles are trimmed to the level of thin shoulder and then graded. Bamboo baskets are the most popular containers for packing papayas.

Papaya fruits should not be allowed to ripen on the tree. Ripe papaya fruit are easily bruised when harvested. Fruits harvested which show traces or yellow were ripen in 4 to 5 days.

The plant will keep on fruiting for many years but production declines rapidly as it grow older. The productive life span of papaya plantations end after 3 ½ years. The yield of well managed papaya plantation is 35 to 40 tons of fruits per hectare which is roughly 4 times the average yield (national) of 10 tons per half/per year.

HANDLING AND STORAGE

Fruits are highly perishable. Carefully handle the fruits from harvesting to shipping to avoid loses due to spoilage in transit and storage.

Papaya can be kept longer if stored in a low temperature regime. The ripe fruits can be kept for a period of 3 weeks if stored at 8⁰C and partially ripe fruits at 12⁰C to avoid chilling, do not store the mature fruits below 7⁰C.

CONCLUSION

Papaya production will also be a profitable enterprise like other crops if good management practice and good variety esp. the hybrid will be used. It can be a good source of income.

BIBLIOGRAPHY

Asis, Consuelo. Plants of the Philipines. Vol. 1 and 2. 1971. M and L Licudine Enterprises. Pp. 123- 124.

Dagoon, Jesse D. Farm Crop Production and Agroforestry. First Ed. 2000. Rex Printing Company INC. Quezon City. Pp. 326-336.

Department of Agriculture. Papaya.

Hartman, Hudson T., Dale E. Kester and Fred T. Davies Sr. Plant Propagation: Principles,

Practices. 5^th ed. 1990. Prentice Hall International Ed.

”High-tech Tactics May Cut Papaya Replanting Costs”. Agriculture Magazine: New Papaya has Sweet Mango and Coconut Flavor issue. Pp. 8-10, February 2004.

“How to Grow Sinta Papaya”. Agriculture Magazine. Pp. 6-7, May 1999.