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3. Potential Fruits


3.1 Durian

(Bombaceae, 2n = 56)

3.1.1 Names:

Scientific: Durio zebethinus Murray

Vernacular:

English: Durian
French: Durian
Indonesia: Durian (In), Duren, Ambetan (Jv), Kadu (Su)
Malaysia: Durian
Philippines: Durian
Thailand: Thurian
Vietnam: Sau Rieng

3.1.2 General: Main production areas in Vietnam are: Dong Nai, Tien Giang, Ben Tre, BariaVungtau, Lam Dong, Binh Duong, Vinh Long, and Can Tho.

3.1.3 Origin and distribution: Durian, originated in the rain forests of peninsular Malaysia, and Borneo, Since ancient times durian has spread to all Southeast Asian countries and more recently to Sri Lanka and south India. It is now being grown on small scale in other regions such as Australia, Hawaii and Brazil. In Vietnam, it is mainly cultivated in the South but there are some orchardsin the highlands in Lam Dong province at elevation of about 600 to 1000 mm.

3.1.4 Description: A medium to large tree growing up to 20 to 40 m or more. Leaves alternate, obovate oblong, 10 to 20 cm long, 4 to 5 cm wide, shiny, smooth and dark green above, silvery, cinnamon-coloured or light golden yellow and scaly beneath. Inflorescence on older branches, 3 to 30 flowers up to 15 cm long. Fruits round to oblong, green to yellow-brown, 15 to 25 cm long, 13 to 16 cm in diameter and may exceed 3 kg in weight. The thick rind is covered with coarse, hard, broadly pyramidal sharp spines. On ripening, the fruit splits open into four to six segments from the apex, revealing compartments containing a mass of flesh (aril), which encloses the seeds. The flesh is yellowish white, pale yellow or orange, buttery, melting, sweet and mild to strongly aromatic which is loved by the native people of Southeast Asia but often found quite repugnant by foreigners. Some cultivars originated in Thailand have a mild aroma, which is more acceptable to foreigners and relished by some.

3.1.5 Ecology: Durian requires a hot, humid climate for luxuriant growth but can also be grown in slightly cooler areas such as the highlands in the tropics and high latitude region such as in Hawaii. A well-distributed rainfall of 1 500 mm per year or more is needed, but relatively dry spells stimulate and synchronize flowering. It thrives well in deep, well-drained and light soil, but also grows normally in heavy soil provided there is good drainage. Due to its heavy bearing and the weight of numerous large fruits on a branch, a sheltered site is desirable to prevent damage from strong winds.

3.1.6 Genetics and Improvement: Originally, durian fruits were collected from the wild. Existing cultivars were obtained from a selection of chance seedlings and somatic mutations, many of which are of excellent quality with respect to the pulp thickness and small seed. In Thailand, cultivars have been selected on the basis of less pungent aroma, while strong aroma is still preferred in many Southeast Asian countries. Very few breeding programmes have been initiated, mostly in Malaysia and Thailand. Few cultivars are available in Vietnam and their quality is still poor according to international standards.

3.1.7 Major cultivars in Vietnam: Commercial cultivars include ‘Sua Hat Lep’, ‘Hat Lep’, ‘Ri-6’ and ‘Kho Qua Xanh’. Cultivars from Thailand are now available in commercial nurseries. Table 9 shows durian cultivars in Vietnam, their characters and location of cultivation.

Table 9. Durian cultivars in Vietnam, their characters and location of cultivation

Cultivar

Character

Location of cultivation

Com Vang,
Sua Hat Lep

Vigorous growth, fruit round, average weight 2.5-2.7 kg; flesh yellow, soft, fine, and non-fibrous; high edible portion (26-30%), taste sweet, creamy with attractive aroma; small seed

- Cho Lach district, Ben Tre province
- Binh Duong district, Binh Phuoc province

Hat Lep,
Dong Nai

Vigorous growth, fruit elliptical, average weight 1.5-1.8 kg; flesh yellow, firm, fine, dry and non-fibrous;. high edible portion (29.6%), taste sweet, creamy with attractive aroma

- Long Khanh district, Dong Nai province

Kho Qua Xanh

Vigorous growth, fruit elliptical, average weight 1.5-1.8 kg; flesh light yellow, soft and fibrous; medium edible portion (15-17%), taste sweet, fat and bitter with attractive aroma; high yield

- Ngu Hiep district, Tien Giang province

Ri-6

Small seed

- Vinh Long

3.1.8 Propagation: In Vietnam, as well as in some other countries like Indonesia and the Philippines, it is a common practice to grow durian from seeds, which are not true-to-type, with a large amount of variation. In Thailand, only grafted plants are used.

3.1.9 Planting: Young durian plants develop slowly with weak roots. The young plants should be kept in the nursery for about one year before field planting. Spacing varies from 8 to 16m apart, with 10 x 10 m the most common spacing. At the closer spacing the orchard may need to be thinned after 8 to 10 years.

As young durian plants cannot tolerate strong winds and sunlight, they are normally planted together with other nurse trees, such as bananas in a mixed plantation. Planting should be done in the rainy season.

3.1.10 Pests and diseases: Durian trees do not have serious pests, except for a few insects such as peach moth (Conogethes punetferalis. However, durians are affected by a number of serious diseases, particularly root rot or patch canker (Phytopthora palmivora), especially in waterlogged soils. The first sign of the disease is the production of brownish red gum from the stem in the collar region. Later, the infection spreads to the vascular elements. Gumming and discoloration extend slowly around the trunk. Before the trunk is fully girdled, terminal shoots shed leaves and die back, and the roots are infected and decay. An IPM method and phosphonate are recommended to solve such problems

3.1.11 Fruiting season: May to November (peak period June to July).

3.1.12 Harvesting and yield: Trees grown from seedlings take 7 to 8 years to start bearing fruits while those grown from grafts may take 5 to 6 years. The fruits usually take 4 months from flowering to maturity after which they drop to the ground. As the trees are tall and quite difficult to climb, many growers prefer to allow the fruits to drop after ripening. Having rather long and strong spines that protect the inside portion, the fallen fruit is rarely bruised. In Thailand and some orchards in Malaysia, where durian trees are grown from grafted plants the fruits are picked before they fall. Maturity is indicated by a hollow sound as the fruits are tapped on the spines of the fruit.

As many as 100 fruits or even more are produced on a healthy mature tree in a single season. The tree continues to bear for about 60 years or longer, provided it is disease free.

3.1.13 Post-harvest operations: Fermentation sets in as soon as fruits drop from the tree and Fruits spoil within a few days. Those picked before ripening can last more than a week. The fruits are considered ripe when they emit their characteristic odor. To open the fruit, a sharp, pointed knife is inserted through longitudinal marks, and segments areforced to split apart. Once open, the fruit should be eaten immediately, but the flesh, sealed in plastic container, can be kept in the refrigerator for a week or in the freezer for months without spoiling and without changing its flavor.

3.1.14 Problems: Main problems inVietnam include the lack of good cultivars since most of the existing plants were grown from seedsand they are not uniform, thus the quality of the fruits is not standardized and normally quite poor. Poor quality grafted plants originating from unknown cultivars are a further problem. The fruits that drop from the tree when ripe also create a problem in marketing.

3.1.15 Prospects: A suitable climate favourable to durian trees and the high price willingly paid by the consumers, makes growing durian on a large scale in the South a good prospect even if mainly for domestic consumption. New cultivars should be developed and clonal propagation (by grafting) should be practiced. Many good cultivars have already been introduced from Thailand, and these should be emphasised for propagation. Sua Hat Lep and Ri-6 are outstanding cultivars that were recommended by SOFRI for more propagation.

3.2 Persimmon

(Ebenaceae, 2n = 90)

3.2.1 Names:

Scientific: Diospyros kaki L.f.

Vernacular:

English: Persimmon, oriental persimmon, Chinese persimmon, Japanese persimmon
French: Plaqueminier, Kaki, Raquemine
Indonesia: Kesemek, Buah Kaki
Malaysia: Buah Kaki, Buah Samak
Philippines: None
Thai: Phlap Chin
Vietnamese: Hong

3.2.2 General: Persimmon is known as ‘oriental product of beauty’ as the fruit has a very good appearance, and in Vietnam it is often placed on the ancestral altar on anniversaries and lunar New Year festivals. Although commercial production is still small, persimmon has long been grown as a traditional fruit in Vietnam. This is evident from numerous ancient documents, folk songs and proverbs. They are considered by Vietnamese as precious fruits to be presented as gifts to relatives, particularly parents-in-law.

3.2.3 Origin and distribution: Oriental persimmon originated in China and has been introduced to Japan since ancient times. Both China and Japan remain the main areas of commercial cultivation but smaller areas have developed in the US, Brazil, Italy and Israel. In SE Asia, it is grown on a limited scale in Java, Sumatra, Malaysia and northern Thailand and Vietnam. Most cultivars are derived from the material of astringent types introduced from China in recent times. However, in Japan the no-astringent Fuyu types have now been popularised there as well as in New Zealand and Auatralia.

3.2.4 Description: A slow-growing, long-living, deciduous, medium-sized tree. It has a short, trunk and a profusely branched crown. Male and female flowers are borne separately although in some cultivars, the central flower of an otherwise male cluster is hermaphrodite. Mature fruit is reddish, orange in color resembling a tomato, and variable in shape, color and size.. The edible parts aremade up of thick segments, enclosing few to many seeds, depending on cultivar and pollinator used.

3.2.5 Ecology: Although subtropical in origin, persimmon is adaptive to a wide range of climates from tropical highlands such as in northern Thailand and Vietnam, to the lowlands of Kuching. However, successful cultivation in the tropics should be in the highlands above 1000m. Young foliage should be protected fromstrong winds through the use of windbreaks or shelters, which also prevent blemishes from occurring on the fruits, from wind rubbing. Persimmon can be grown ona wide range of soils but prefers well-drained, deep soils that are not too heavy with pH around 5.5 to 6.5.

3.2.6 Genetics and improvement: A number of breeding programmes have been initiated in Japan and China resulting in a large number of improved cultivars. However, very few cultivars are widely available in the tropics as yet with mostderived from selection of older introduced cultivars.

3.2.7 Major cultivars in Vietnam: Major cultivars of persimmon in Vietnam include ‘Thach That’, ‘Nhan Hau’, ‘Son Suong’, and ‘Hac Tri’. Their charcters and location ofcultivation are given in Table 10. In the South, ‘Trung loc’, ‘Fuzu’, ‘Vuong’ now are grown in Don duong and Da Lat, Lam Dong province

Table 10. Major cultivars of persimmon in Vietnam and location of cultivation

Cultivar

Location of cultivation

Thach That

North

Nhan Hau

North

Trung Loc

Da Lat, Lam Dong

Fuzu

Da Lat, Lam Dong

Vuong (Tam Hai)

Don Duong, Lam Dong

Vuong (Ong Dong)

Don Duong, Lam Dong

3.2.8 Propagation: Originally, persimmon was propagated by root shoots (i.e. division of roots that produce new shoots) or root cuttings. Normal cuttings are difficult to root, without special techniques. Plants produced from seed tend to be weak. Recently, however, anew patch budding technique of propagation has been introduced for grafting mature buds onto seedling stocks, inVietnam. In most other countries budding or grafting is the normal practice.

3.2.9 Planting: Field planting is done when the trees are dormant, and leafless. Care should be taken during planting, trying not to disturb root system. Spacing depends on the vigor of the cultivar; recommendations range from 5 x 5, 6 x 4.5, 5 x 2.5 m. In the tropics growth is normally more vigorous, thus requiring wider spacing. Spacing depends on vigour of the cultivar and the roostock chose, but in Vietnam normally a spacing of 8 x 8m is employed.

3.2.10 Pests and diseases: Persimmon has relatively few pests and diseases in Vietnam. In other tropical countries such as in Java, a few pests have been reported such as various aphids (Toxoptera aurantii, Toxoptera citricidus); similarly only a few diseases have been reported in Southeast Asia including pink disease (Corticium salmonicolor).

3.2.11 Fruiting season: September to November in Vietnam.

3.2.12 Harvesting and yield: Yields of 20 to 50 t/ha per year are reported for mature orchards (8 years old), but much lower yields have been observed in Vietnam.

3.2.13 Post-harvest operations: Most tropical persimmons are astringent. In Vietnam, with small-scale production, ripe fruits are put in a covered vase with some burning josssticks to remove astringent taste. When fully ripe, the pulp is soft and cannot endure long transportation. Simply holding immature fruits in a warm place for a wwek or so will allow them to ripen to a very soft almost jam soft state, when they are ready for eating. In Indonesia, semi-ripe fruits are harvested and soaked in slaked lime for 24 hours. Fruits so treated are sweet and firm but have patches of powdery white lime on the skin. Other methods include treating the semi-ripe fruits in sealed rooms or containers with ethyl alcohol or carbon dioxide, or dropping the fruits into boiling water and allowing to soak and cool overnight, or putting into a freezer for 24 hours. Ethylene treatment also accelerates ripening, as will enclosing them in a ventilated polythene or paper bag with a ripe banana or apple for a few days. Fruits dipped in a 1-2 % Ethrel solution will ripen more quickly. Non-astringent cultivars may be eaten while the fruit is firm and crunchy like an apple. However, may people rightly say that non-astrigent persimmon lacks the delicious flavour and aroma of ripe non-astringent cultivars.

Astringency disappears when the fruit is dried. Drying is used to prepare an excellent fig-like product. The fully ripe fruit is peeled and strung by the stalks to dry in the sun or in the rooms kept at 35°C. The semi-dry fruits are flattened gradually in a wooden press and dried again. The final product is white because sugar crystallizes on the surface. In Indonesia, ripe fruits are steamed until soft and pressed flat and dried into ‘red figs’.

3.2.14 Problems: Unlike other fruits, freshly picked, immature, firm, astringent persimmon fruits cannot be consumed in a firm state as they are very astringent and must be treated as mentioned above before eating. The non-astringent ripe fruits are soft, sweet with nice aroma and taste. However, such a condition cannot endure long transportation. In commercial practice, persimmons are transported when freshly picked and ripen at the site where they are consumed. This may be a big problem for those who normally do not know the technique of ripening and this often makes persimmon unpopular in spite of the fact that it is one of the nature’s best quality fruits.

The biggest problems in commercial-scale cultivation in Vietnam are the lack of existing technology, especially suitable cultivars to be grown in specific zones, and the lack of experience in post-harvest technology, transportation and marketing.

3.2.15 Prospects: Persimmon is one of the best of the fruit species for the tropical highlands of Vietnam. It can also be grown in several other regions such as hilly lands, in the Red River Delta, and on acid soil of the central areas. Being an easy crop to grow, once established, it has stable output (unlike lychee or longan which are also grown in similar habitat). Persimmon has few pests and diseases, with high quality fruits, persimmon is an ideal tree crop to be promoted in more remote locations both to satisfy local demand, transport to large regional markets and for export either as fresh fruits or processed products.

3.3 Pineapple

(Bromeliaceae, 2n = 50)

3.3.1 Names:

Scientific: Ananas comosus (L.) Merr.

Vernacular:

English: Pineapple
French: Ananas, Pain ade Sucre
Indonesia: Nanas (Javanese), Danas (Sundanese), Naneh (Sumatra)
Malaysia: Nanas, Nanas Pager
Philippines: Apangdan (Bantok)
Thai: Sapparot
Vietnam: Dua, Thom

3.3.2 General: Pineapple is widely grown in many tropical countries for domestic consumption or for export, either fresh or processed. It is the second (after banana) most important fruit of Vietnam in terms of area planted and production and the most important one in terms of processed fruit. At present the main production areas in Vietnam are in the North: Bac Giang, Thai Nguyen, Phu Tho, Son Tay, Ninh Binh, Thanh Hoa, Nghe An; and in the South: Tien Giang, Kien Giang, Long An, Lon Gan, Can Tho, Soc Trang, Minh Hai, Ho Chi Minh City and Lam Dong.

3.3.3 Origin and distribution: The pineapple originates in eastern South America where it was cultivated well before the time of Columbus. The Spaniards took the pineapple to the Philippines and Peninsular Malaysia. It is now widely grown throughout the tropics and sub-tropics. International canning industries are based on plantations in Thailand, the Philippines, Indonesia, Malaysia, as well as several other countries in Africa and South America.

3.3.4 Description: Pineapple is a perennial herb, 90 to 120 cm tall. Sword-shaped leaves, up to 1 m or more long, 5 to 8 cm wide are arranged in a bushy rosette on the stem. Fruit develops from a whole inflorescence with many flowers and not from a single flower as in most other fruits. Fruit is cylindrical in shape, about 20 cm long and 14 cm in diameter, weighing1 to 2.5 kg. On top of the fruit is a rosette of short, stiff, spirally arranged leaves called the ‘crown’ (which can be used to propagate). Flesh is pale to golden yellow usually seedless. Besides the crown, ‘slips’ (shoots growing on the stem below the fruit) and ‘suckers’ (shoots growing in leaf axils lower down the stem) can be used for vegetative propagation.

3.3.5 Ecology: The pineapple is mostly cultivated in the tropics between 25°N and S. Temperature range of growing areas is 23 to 32°C. Pineapple cannot tolerate frost, and high temperatures, and fruit is sensitive to sunburn, but can withstand considerable drought. Continuous warm conditions favor rapid growth and development. The fruit takes longer to grow at higher altitudes and latitudes, where temperatures are lower. Pineapple must have an acid soil qith pH around 4-5 or it will not grow successfully. Fertile soils are not required, provided nutrients are added.

3.3.6 Genetics and improvement: Most pineapple breeding has been based on mass selection or individual plant selection and followed by clonal multiplication. Cross-pollination in pineapple is quite simple and the seeds can be removed from the fruit without difficulty. Seeds germinate slowly; seedlings take about 18 months in the nursery and 18 to 30 months in the field before fruit is produced. Selected plants are cloned and then tested. Pineapple breeding is aimed at improving fruit quality for canning; thus the shape and size of fruit are important. Moreover the fruit should have a high sugar/acid ration, more uniform ripening, higher vitamin C content and absence of seeds. In Australia pineapples have been specifically bred for the fresh-fruit market.

3.3.7 Major cultivars in Vietnam: Originally there were two cultivars of pineapple in Vietnam namely ‘Ta’ and ‘Tay’. The former is a Spanish type, also known as ‘local’ cultivar since it has long been growing in Vietnam in Erythropleum and Canarium forests. ‘Tay’ is a Victoria/Queen rough leaf type, also known as ‘western’ pineapple in Vietnam, which is cultivated either as a monocrop or as intercrop (between orange, mandarin, tea and cotton). The local cultivars of the Queen group are very tasty for fresh consumtion. These cultivars presently used in processing are not suitable for canning. Recently, there has been an intensive study on varietal adaptability of the Smooth Cayenne cultivars that are used throughout the world in the pineapple industry. From the study it was found that ‘China’ and ‘Chan Mong’ cultivars, which can be grown successfully in the North are considered to be favorable for processing. Hawaiian and Australian clones were introduced in the south in 1999, but in the South the long dry season is not conducive to commercial production, unless irrigation is provided, as shown in 1999-2000.

3.3.8 Propagation: In most pineapple-producing countries, pineapple is propagated by crowns, slips or suckers. Slips are most commonly used in Vietnam. However, in some commercial cultivars such as Smooth Cayenne, few slips are produced, thus suckers are used instead. (In Thailand, the largest canned pineapple exporting country in the world, crowns of Smooth Cayenne are preferred.)

3.3.9 Planting: Planting is usually in double rows with a spacing of 60 x 30 cm with 90 cm path for Singapore Spanish cultivar, and 50 x 30 cm with 100 cm path for Smooth Cayenne. Planting is done by hand along planting lines marked with the plant positions.

3.3.10 Pests and diseases: Fruit collapse a few weeks before maturity is caused by Erwinia chrysanthemi, and is serious in Singapore Spanish. The Cayenne and Queen pineapples appear to be resistant to this bacterium. Other diseases include heart rot (Pythium butleri and Thielaviopsis paradoxa.), marbling (Acetobacter peroxydans), leathery pocket (Penicillium funiculosum), fruitlet core rot (Penicillium funiculosum), soft rot (Chalara paradoxa) and inter-fruitlet corking (boron deficiency).

3.3.11 Fruiting season: Fruits can be harvested all year round although the plant can be forced to flower almost any time of the year, depending on climates, through the use of a chemical (ethylene and other inductants) in order to facilitate harvesting.

3.3.12 Harvesting and yield: In North Vietnam, a yield of 10 to 12 t/ha of Smooth Cayenne cultivar is obtained which is much lower than the average mean yield of 25 t/ha obtained in many Southeast Asian countries, and Australia where Smooth Cayenne plant crops average over 80 t/ha.

3.3.13 Post-harvest operations: No special post-harvest treatment is necessary. For long transportation to the processing factory, normally the crowns and fruit stalks are cut off to save space, but for fresh market, the crown should remain. Storing in a cool shady placae will prolong the shelf life of the fruit. Pineapple is a non-climacteric fruit and does not ripen further after harvest.

3.3.14 Problems: Pineapple cannot withstand the waterlogging conditions that are prevalent in the delta areas. At present, the cultivar used in commercial plantation for the processing industry is the Queen type that produces small, spherical fruit unsuitable for canning as there is a lot of wastage.

3.3.15 Prospects: There are large areas that would be suitable for pineapple growing pineapple in both the North and the South, provided the dry-season water deficit is met in the South. Pineapple can help to satisfy the year-round demand of raw materials for the canneries already present in Vietnam. If good adapted cultivars for canning (i.e. Smooth Cayenne) were introduced from Thailand, China, Auatralia or Taiwan, Vietnam would be able to produce processed pineapple on a competitive basis for international market.

3.4 Rambutan

(Sapindaceae, 2n = 22)

3.4.1 Names:

Scientific: Nephelium lappaceum Linn.

Vernacular:

English: Rambutan
French: Litchi chevulu
Indonesia: Rambutan
Malaysia: Rambutan
Philippines: Rambutan, Usan
Thailand: Ngo
Vietnam: Chom Chom

3.4.2 General: Main areas of production are: Dong Nai, Binh Duong, Baria Vungtau, Tien Giang, Ben Tre, Vinh Long, Tra Vinh and Can Tho.

3.4.3 Origin and distribution: Rambutan origin is uncertain. The species ranges from southern China (Yunnan and Hainan) through Indo-China, Malaysia, Indonesia, to the Philippines. It is now cultivated in most Southeast Asian countries, Sri Lanka and in small areas in the humid tropics of America, Africa and Australia. In Vietnam, it is grown in the Mekong Delta where the climate is hot and humid.

3.4.4 Description: A medium-sized tree, 4 to 7m tall and usually with a spreading canopy. Rambutan has a terminal inflorescence. There are two forms of trees: staminate and hermaphrodite. Staminate trees produce only male flowers (only stamens are well developed) while hermaphrodite trees produce two forms of hermaphrodite flowers; one functioning as female (with small stamens), the other functioning as male (with stigma not opening). They are white yellowish or green in color. Trees that are hemaphroditic with both functionally female and fuctionally male flowers are the most common cultivars grown. The fruit is ellipsoid to subglobular, up to 7 x 5 cm, weighing 20 to 95 g, consisting of a single seed enclosed by a translucent aril whose flesh is creamy white with a distinct flavor and sweet taste. The outer skin is covered with soft hair (technically known as tubercles) of different length and colours, ranging from green to yellow to red or pink, with a skin colour also similarly variable.

3.4.5 Ecology: Rambutan thrives in humid tropical lowlands within about 17° from the equator. It requires high rainfall, 2 500 mm or more, so it is intolerant of drought and dry winds. It requires well-drained soils of sandy or clay loam with pH range of 4.5 to 6.5.

3.5.6 Genetics and improvement: There has been no genetic study in rambutan. Present cultivars were obtained either from chance seedlings or somatic mutation of wild species.

3.5.7 Major cultivars in Vietnam: Although a common plant in the South, no varietal designation is available as most trees are grown from seedlings air layering or grafting from selected mother trees with no clear varietal designation. Two distinct types have been observed, ‘Java’ and ‘Nhan’. The former type might have been introduced from Taiwan or Indonesia long time ago; its quality is poor and is being replaced by a Thai variety. The latter has very nice taste and is presently popularly grown in Vietnam.

3.5.8 Propagation: In Vietnam rambutan is normally propagated by air layering. However, grafting, particularly top-grafting, is becoming more popular to replace varieties having inferior quality. Modified Forkert budding is now a common practice in Vietnam.

3.5.9 Planting: Spacing for rambutan trees is 8 x 8 m. However, other spacings have also been observed, depending on the vigour of the stock-scion combination and on the growing conditions, for example, soil depth and fertility, irrigation. Intercropping is quite common in commercial orchards and durian, mangosteen, and langsat are usually planted along with rambutan.

3.5.10 Pests and diseases: Rambutan has no serious pests and diseases. In certain areas powdery mildew (Oidium nepheli) may be observed during blooming stage; it is controlled by sulphur spray.

3.5.11 Fruiting season: April to September (peak season June to July).

3.5.12 Harvesting and yield: Being a non-climacteric fruit, rambutan should be harvested when ripe. Entire panicles are twisted or cut off the tree using a bamboo pole with a cutting attachment and basket. An average yield of 4 to 5 t/ha is expected from a mature rambutan orchard, while NIAPP (1994) cited an average yield of 10 t/ha. If grown under optimum conditions, a yield of 20 t/ha can be expected.

3.5.13 Post-harvest operations: After picking, the panicles are bunched together for sale. In some areas, individual fruits are detached before marketing. The soft, long hairs covering the skin protect rambutan fruit against bruising during transport. The shelflife of fruits is only a few days, mainly because the fruit loses water rapidly and the hairs and skin turn black.

3.5.14 Problems: Lack of good, reliable cultivars with thick flesh easily separated from the seeds is a major drawback of rambutan cultivation in Vietnam as it is in other rabutan growing countries. Having a very short shelflife of only a few days is also a big problem in marketing.

3.5.15 Prospects: Rambutan has good prospects as the yield can be increased significantly with improved cultural techniques, better cultivars and post-harvest treatment. For fresh consumption, keeping the fruits moist and shaded will prolong their shelflife considerably. Fruits packed in shrink-wrapped containers allows fruit to arrive at the market in excellent condition. Cold storage at 12°C and fungicidal treatment can also extend the shelflife. Processing offers good prospects, especially for export, for example, as canned rambutan, either singly or in combination with pineapple (rambutan stuffed with a pineapple chunk).


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