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4. Other Fruits

4.1 Avocado

(Lauraceae, 2n = 24)

4.1.1 Names:

Scientific: Persea americana Miller


English: Avocado
French: Avocatier
Indonesia: Adpukat, Avokat
Malaysia: Avokado, Buah Mentega, Apukado
Philippines: Avocado
Thai: Awokhado, Luk Noei
Vietnam: Bo, Le Dau

4.1.2 General: Avocados are mostly consumed fresh as a salad fruit. However, in Viet Nam avocado mostly used as juice by grinding the flesh and mixing with milk giving a nice taste of a kind of a drink. The better cultivars for the world market are high in oil and low in sugar. The oil content varies with genetic and environmental factors, fruit age and ripeness from 5 to 25% of pulp weight. Low oil content, West Indian cultivars are not the preferred avaocdo of commerce. The main components of the very digestible oil are the unsaturated fatty acids - oleic and linoleic, and a saturated fatty acid - palmitic acid. The amino acid balance of the protein is ideal for human consumption and avocados are a good source of vitamins A, B (thiamine), C and G. On a world scale, avocados are not a major crop. Most of the crop is grown for home consumption, but a few countries, notably South Africa, Israel, USA, Chile, USA, Mexico, Australia, South Africa, and Kenya among others, export fresh fruit to Europe. In Vietnam, avocados are mainly grown in the highlands (in Lam Dong province) and in the Mekong Delta areas.

4.1.3 Origin and distribution: Avocados originated in Central America. When the Spanish arrived in Latin America in the 15th century they found three races of avocados - Mexican, West Indian and Guatemalan. The transfer of races outside their areas of origin resulted in the development of hybrids. Avocados are now widely grown throughout the tropics and sub-tropics.

4.1.4 Description: An evergreen tree up to 20 m high. Leaves are simple, elliptic, ovate-oblong or obovate-oblong. Inflorescence is a compact axillary panicle crowded at the ends of branches. Flowers are numerous greenish-yellow with 6 perianth segments; stamen 9, perfect, arranged in 3 series; ovary with a single ovule. Pollination in avocados is complex, and A and B type trees exist with respect to flower opening and pollen receptivity. The fruit is a large fleshy berry, pyriform, round or globose, 7 to 20 cm long. The edible mesocarp is yellow or yellowish-green and with a butter-like consistency. The fruits contain a seed single, which is large, globose to pyriform with two seed coats and two large firm, almost hemi-spherical cotyledons, 2-4 cm in diameter enclosing a small embryo.

4.1.5 Ecology: The ecological requirements of avocados vary somewhat with races. They are sensitive to frost, especially the West Indian one, being particularly susceptible during flowering. Mexican cultivars are rather less susceptible to cold than West Indian and Guatemalan cultivars. They grow well in a wide range of soil type from sandy to clay loams, but the roots must not be waterlogged. High or low pH and salinity may be a problem in some areas, as the preferred pH range is 5.5 to 6.5 and the trees are intolerant of salinity, which is found in parts of the Mekong delta.

4.1.6 Genetics and improvement: The genus Persea has 2n = 2x = 24. Desirable fruit types were presumably selected by the South American Indians, and these seeds resulting from uncontrolled pollination were planted. Genetic improvement based on controlled pollination and selection has only been attempted in a few countries, notably Australia, Israel and U.S.A. Major aims in the breeding of rootstocks include: resistance to root rot; tolerance to salinity, high pH, low soil temperature at higher latitudes and altitudes. The aims in breeding scions include: spreading habit; cold hardiness; heat tolerance; early, heavy and consistent yield; fruits of the required weight, shape, skin and flesh color, flavor, storage and ripening behavior and oil content.

Avocado trees may be grouped into two classes: the flowers of class A open first in the morning and a second time the following afternoon; class B flowers open first in the afternoon and again the next morning. The flowering mechanism is partly controlled by weather conditions and ensures cross-pollination unless the two stages overlap, as sometimes happens. Pollination is by insects, often bees.

4.1.7 Major cultivars: There are several hundred named avocado cultivars, but most of the crop is produced from only a few of them. Cultivars are classified primarily on the basis of the three botanical cultivars, commonly called West Indian, Mexican and Guatemalan races, but there may also be natural or man-made hybrids. Unfortunately, there is no varietal name of avocado in Vietnam since most have been propagated from seed. However, there has been some selection of superior types for propagation, like S1-D-T, S1-Bd-T, S2-Bd-T. Cultivars which are grown in the lowlands of the Mekong delta are of West Indian origin, while those in the highlands are a mix of West Indian, Mexican and Guatemalan races. From the result of the recent fruit contest, the introduced cultivars, i.e. Hass, Ettingger, Fuert, Reed were introduced by SOFRI to be grown in Da Lat. Some local cultivars include Sap, Sap Trai Dai, Sap Trai Nho, Sap Tron and Trai Dai Com Vang.

4.1.8 Propagation: Avocados in Vietnam are generally propagated from seeds that have to be sown very soon after removing from the fruits. Modern plantations are usually established through budding or grafting selected cultivars on to the seedling rootstocks. To date virtually no grafting is practiced in Vietnam.

4.1.9 Planting: In Vietnam, seeds may be directly sown into planting positions, usually two to three seeds per hole and the strongest seedling is selected to grow further or to be field grafted. They may also be pre-germinated in sand or sawdust and then transferred to containers or larger black polythene bags, where they are grafted and grown to a suitable size for field planting. During orchard establishment, field crops or vegetables may be grown between the trees. Spacing of trees varies from 6 to 12 m on the square (280 to 69 trees/ha). Close spacing improves yields for the first six to eight years, but thereafter tree removal, or pruning becomes necessary.

During the first year the tree requires special protection against wind. Avocados have a rapid turnover of leaves and after a few years the fallen leaves provide a measure of self-mulching. In humid areas, cover crops of sorghum or maize raise soil organic matter and inhibit root rot, caused by Phytophthora cinnamomi.

4.1.10 Pests and diseases: The most severe fungal disease is root rot caused by Phytophthora cinnamomi, which results in tree decline and death. The disease is serious on poorly drained soils. Creation of a Phytophthora suppressive soil under the tree canopy, by using wide C/N ratio, mulches, 10-15 cm deep, with straw, and the application of organic manures greatly assists with control of Phytophthora. Successful long-term production requires land with well-drained soils and a continuous programme of cultural and chemical control measures. Compared to other crops, avocados require a high level of care and management, if Phytophthora cinnamomi is present. Care should be taken to use disease-free planting material, raised in sterilized soil in a nursery.

Other diseases affecting leaves and fruit include anthracnose (Colletotrichum gloeosporioides), cercospora spot blotch (Cercospora purpurea) and scab (Sphaceloma perseae). In isolated areas where avacados have been planted from seed the tree may be completely free of these diseases, including Phytophthora and great care must be exercised in introducing new grafted plants into such areas as they are likely to carry disease.

More than 30 insect and mite pests attack avocado trees, but only about a dozen cause significant problems. Various fruit flies attack the fruit causing superficial damage; although larvae rarely develop in fruit, this can be a reason to refuse entry to some markets. Fruit spotting bugs (Amblypelta nitida) cause deep fruit lesions in older fruit; young fruit will usually fall from the tree when ‘stung’. Various webbing caterpillars, including avocado leafroller (Homona spargotis) and ivy leafroller (Cryptopila immersana) can cause severe leaf damage as they roll and web leaves together, forming shelters from which to attack the fruit. Often the fruit may be infected with anthracnose (Colletotrichum gloeosporioides) and drop; even if the damage heals, the fruit is rarely marketable.

Loopers, including the ectropis looper (Ectropis sabulosa), can cause serious damage to fruits and leaves. In severe infestations, the tree may be completely defoliated exposing fruit to sunburn. Larvae also damage the skin of the fruit leaving rough brown scars.

All pests can be controlled with contact insecticides if carefully timed.

4.1.11 Fruiting season: Almost all year round although there are peaks of production in certain months (March to July) when there are good rainfalls and temperatures.

4.1.12 Harvesting and yield: Maturity is judged by the ability of the fruit to soften and become palatable without shriveling or showing flesh breakdown once it is harvested. Because of protracted flowering, the fruit matures over a period of time. Selective picking should be practiced as this gives the remaining immature fruit the opportunity to grow on to maturity. Yields vary according to cultivar and cultural practices as well as climatic conditions. On average, a yield of 3.5 to 5.0 t/ha is obtained in Vietnam, but a much higher yield can be achieved and in a well-managed orchard up to 25 t/ha may be produced.

4.1.13 Post-harvest operation: Fruit is clipped from the tree, retaining a pedicel button that prevents the entrance of post-harvest disease through the fruit stalk scar. In many countries, fruit is simply shaken from the tree or thrown to catchers by boys climbing the trees. Picking from ladders into picking bags or with a picking pole fitted with a hook and a collection bag is recommended. Fruits must be handled carefully to avoid bruising. After picking, the fruit should be shielded from direct sunlight to prevent the build-up of field heat and reduce internal damage.

Gentle brushing of the fruit removes field bloom, scale insects and traces of fungicide, giving the fruit an attractive luster. Fruit reaches the eating-ripe stage within 4 to 14 days from picking depending on its stage of maturity and the ambient temperature. In Vietnam, there is little sophistication in post-harvest handling. Generally fruit is transported to local markets in open baskets or crates.

4.1.14 Problems: Diseases are the major problem in avocado and there are at present very few disease resistant cultivars. Several sources of resistance to root rot disease can be obtained from disease tolerant rootstocks that must be propogated vegetatively. Such rootstocks are available from countries such as Australia, USA and Israel.

4.1.15 Prospects: Selection within open-pollinated seedlings has resulted in many valuable cultivars, and much has been achieved in the selection of rootstocks, many of which are resistant to diseases including root rot. Because of high world demand due to its versatile uses, there is a great prospect for Vietnam, with its suitable climatic conditions especially on the highlands in Lam Dong province, to embark on a large-scale plantation of avocado for export, especially to nearby countries such as Singapore, Hong Kong, Taiwan, Korea and Japan. However, avocado is a tree crop requiring sophisticated management and propagation techniques for profitable commercial production for export. In the interim avocado should be promoted in isolated communities for improving nutrition of the people. Avocado is the near perfect baby food of the world in terms of balanced nutrition and should be promoted as such to isolated communities. However, great care must be exercised to avoid the introduction of grafted plants with soil and diseased leaves and buds.

4.2 Banana

(Musaceae, 2n = 22 (2x), 33 (3x), 44 (4x))

4.2.1 Names:

Scientific: Musa sp.


English: Banana
French: Bananier
Indonesia: Pisang
Malaysia: Pisang
Philippines: Saging
Thai: Kluai
Vietnam: Choui

4.2.2 General: Banana is one of the most ancient of food plants cultivated at the dawn of recorded history. It is the most important traditional fruit of Vietnam, both in terms of historical and economic significance. Commercial annual production in Vietnam is over one million tons, not including home gardens, which almost always grow bananas for personal and local use. Main production areas in Vietnam are: Dong Nai, Can Tho, Son Trang, Tien Giang, Vinh Long, Ben Tre, and Vinh Phu provinces.

4.2.3 Origin and distribution: Banana originated in Southeast Asia from two wild species, Musa acuminata (AA) and M. balbisiana (BB), both of which are diploid (2x) with 2n = 22. Depending on their genomic constitutions (A and B), bananas are divided into many distinct groups: diploid - 2x (AA, BB, AB), triploid - 2x (AAA, AAB, ABB, BBB) and tetraploid - 4x (ABBB). In Vietnam, only AA, BB, AAA, AAB, and ABB genomes are found. Most are grown in home gardens; a few are grown in plantations while some are still found in the wild (BB group).

4.2.4 Description: Banana plant is an herbaceous plant growing to 2 to 9 m. It has a false stem known as pseudostem that is formed by overlapping leaf sheaths. These are tightly rolled around each other to form a rigid bundle of 20 to 50 cm in diameter. A short underground stem (rhizome or corm) produces a clump of aerial shoots (suckers) close to the parent plant. New leaves originating from the corm grow up continuously through the center of the pseudostem with the laminas tightly rolled pushing the fruiting stem through the middle. Each plant (stem) produces a single bunch of fruit. After the fruit has ripened and been harvested, the stem is usually cut down allowing the follower stem/sucker to produce the next crop of bananas.

4.2.5 Ecology: Bananas prefer warm, humid tropical climates. Optimal temperature is about 27oC in the range of 15 to 38oC. Most bananas grow best in full sun, but excessive exposure causes sunburn to fruits. They are susceptible to strong wind that shred the leaves, causes crown distortions and will blow plants over. Optimal monthly rainfall is between 200 to 220 mm. The best soil for banana is a deep, friable loam with good drainage and aeration. Banana grows in a wide range of pH, from 4.5 to 7.5 and prefers high fertility with high content of organic matter.

4.2.6 Genetics and improvement: Although originating in Southeast Asia, no breeding has been done in the region. Most research has been concentrated on characterization of various cultivars. Most improvement of banana is through induced mutation in conjunction with tissue culture techniques, although one breeding programme existed in Central America for many years.

4.2.7 Major cultivars in Vietnam: There are sixgenomic groups of bananas in Vietnam. They are:

(1) AA Group: Pisang Mas, Lady’s Finger, Sucrier, Kluai Khai. Cultivars of this group include:

‘Chuoi Ngu’: Its ripe fruit has a paper-thin skin, making transport difficult without damage to the fruit. Its taste is sweet and very aromatic but the yield is rather low. It is called King banana in the North.

‘Chuoi Cau’: It is similar to Chuoi Ngu and is native to the South.

(2) AAA Group: Cavendish, Gros Michel, Pisang Ambon, Kluai Hom Thong. Cultivars of this group include:

‘Chuoi Tieu’ (N) and ‘Chuoi Gia’ (S): They are aromatic bananas and the most important cultivar in Vietnam. The calorific value is not as high as other cultivars (AAB or ABB group) but they are very delicious, aromatic and easily digestible. They can tolerate low temperature quite well, thus can be grown on the highlands in the South (for example in Dalat at 1 500 m), or in the North at 500 to 600 m. Grown in fertile soil and with proper management and fertilizer application, these cultivars produce a high yield. They are sensitive to drought but resistant to many diseases. In the North, the cultivar develops good flavor and aroma with yellow skin covered with black spots when ripe in the winter (22 to 25°C); but in the summer, the ripe bananas have green skin and flabby pulp. There are many forms that differ in height of the plant, quality, shape and colour of the fruit.

(3) AAB Group: Plantain, Pisang Tanduk, Kluai Klai. Only one cultivar is popularly grown, namely:

‘Chuoi Bom’: Cultivated in Dong Nai province (SE), it is very tolerant of drought and poor soil. It matures quite early (six months after planting) and prefers the hilly areas of the South where there is a long dry season.

(4) ABB Group: Bluggoe, Pisang Awak, Kluai Namwa. Cultivars of this group include:

‘Chuoi Tay’ (N) and ‘Chuoi Su’ (S): Tall plant with large, short fruits. (Hai or Minh Chau, can you provide more information on this?). It does well on the highlands, is suited to drying and is more disease tolerant on the highlands.

(5) BB Group: Wild Balbisiana (Pig babana). Only one cultivar is popularly grown, namely:

Chuoi Hot’: Robust tall plant with dark green color; popularly cultivated as its fruit are full of seeds and the plant is very tolerant of low temperatures. It is mainly grown for animal foodstuff. The young stem and unripe fruits are used as fresh vegetables and uncooked food.

4.2.8 Propagation: Bananas are generally propagated by suckers. Sword suckers are preferred since they bear larger bunches in the first crop. Corms can also be used to propagate banana. At present, many countries use tissue-cultured plants for commercial banana growing.

4.2.9 Planting: In Vietnam banana is grown in four distinct cropping systems: home gardens, mixed cropping system in farmers’ fields, commercial small holder orchards and large-scale plantations. In home gardens, numerous cultivars are grown for home consumption using minimal inputs while surplus is sold in the market. This is the most common system in Vietnam. In mixed cropping systems, banana is either the principal or the auxilliary crop, or the nurse crop for young cocoa, coffee or pepper In newly established industrial crops such as oil palm or rubber, banana is grown as an intercrop during the first few years. In large-scale plantations, banana is grown as the principal crop, usually interplanted with annual crops.

4.2.10 Pests and diseases: The most important insect pest is the banana weevil borer (Cosmopolites sordidus). Female weevils lay their eggs on or near the corm. The larvae bore into the corm and destroy a large portion, which they later pupate, resulting in lessening the uptake of water and nutrients as well as the anchorage of the plants. Other pests include two kinds of thrip (Thrips spp.), one attacks developing fruits, resulting in rough skin; the other feeds on the area where the fingers touch. Nematodes (Meloidogyne spp.) attack the roots, causing dark patches or spots on the roots, indicating subsequent fungal infection.

Leaf spot or yellow sigatoka (Cercopspora musae = Mycosphaerella musicola) is one of the most important diseases, causing premature death of large areas of foliage. A more virulent form of leaf spot is black sigatoka (Mycosphaerella fijiensis) caused by a related fungus to the former disease. Another serious fungal disease is fusarium wilt or Panama disease (Fusarium oxysporum cubense race 4). It blocks the vascular system, causing the plant to wilt. Bacterial wilt (Ralstonia solanacearum, ealrier known as Pseudomonas solanacearum), can kill an infected banana plant in just a few weeks. Virus diseases include bunchy top, mosaic and bract mosaic, all are transmitted by aphids (Pentalonia nigronervosa).

4.2.11 Fruiting Season: Bananas produce fruits all year round.

4.2.12 Harvesting and yield: The fruit bunch is harvested when still green. The stage of maturity is judged by the angularity of the fingers, the rounder the fruit the more mature. For export market the fruit is harvested 10 to 14 weeks after flower emergence. The yield varies from 3 to 60 t/ha/year, depending on cultivar and field management.

4.2.13 Post-harvest operations: The harvested bunches are de-handed and fruits washed, sorted and packed in cartons for export. The fruits are treated with fungicides to prevent rotting during transportation. Storage at 13 to 15oC helps to prolong shelf life for about 20 days. Calcium carbide or ethephon solution may be used to ripen green mature fruits. Banana is a climacteric fruit that may be picked green for long distance transport and ripened upon arrival at the designated markets.

4.2.14 Problems: As banana is one of the most common fruits in Vietnam, it is assumed that there is no need for improvement. Currently, there is no cultivar grown commercially for export, and there is no breeding program in any of the fruit research institutes.

4.2.15 Prospects: Banana is native to Southeast Asia and can be grown abundantly in the region. It is the cheapest fruit available and is conveniently available all year. It has multiple uses including processing into different industrial products, such as dried banana. There appears to be ample room for increased local consumption and export market development.

4.3 Breadfruit

(Moraceae, 2n = 28 (2x), 56 (4x))

4.3.1 Names:

Scientific: Artocarpus altilis (Parkinson) Fosberg


English: Breadfruit
French: Arbre a pain
Indonesia: Sukun (seedless), Kelur, Timbul (seeded)
Malaysia: Kelor (seeded)
Philippines: Rimas (seedless), Kamansi (seeded)
Thai: Sa-ke (seedless), Khanun Sampalo (seeded)
Vietnam: Sake

4.3.2 General: The breadfruit is a minor crop on a world scale, but it is quite important in Polynesia where it may supply a large proportion of the daily food. There are seeded and seedless forms of the breadfruit, the pulp of which may be boiled, roasted or steamed and used in various main and side dishes. It has a high nutritional value. The seeds can also be eaten after cooking. Currently the main area of breadfruit cultivation is in the Pacific islands, especially Polynesia, although it is grown throughout the tropics, including Vietnam.

4.3.3 Origin and distribution: Breadfruit originated in the Indo-Malayan Archipelago and Papua New Guinea and spread eastwards over the Micronesian and Polynesian islands many centuries before European explorers first arrived. It was first described in 1595 from its occurrence on Tauta Island in the Marquesa group. The seedless form, which has been cultivated on some Pacific islands for centuries, is a triploid derived from diploid x tetraploid crosses but mutation may also have played a role.

4.3.4 Description: A tree up to 30 m tall, evergreen in the humid tropics, semi-deciduous in monsoon climates. Leaves alternate, ovate to elliptic, undivided when young, older ones entire or deeply pinnately cut into 5 to 11 pointed lobes, dark green above, pale green below. Inflorescence axillary; male flowers drooping, club-shaped, yellow colored; female flowers stiffly upright, globose or cylindrical, green. The fruit botanically is a syncarp formed from the entire inflorescence, and is cylindrical to globose, rind yellow green, sometimes bearing short spines. Most cultivated breadfruits are seedless. All parts of the tree are rich in white gummy latex.

4.3.5 Ecology: The breadfruit is adapted to hot tropical lowland conditions and grows well on a cultivar of soils as long as there is good drainage. Cultivars differ in their tolerance of seasonal drought and soil salinity. The tree is susceptible to wind damage causing branches to break and flowers and young fruit to fall.

4.3.6 Genetics and Improvement: Variable 2n numbers have been reported for the breadfruit, viz. 54, 56, and 81. The basic chromosome number of the genus Artocarpus is probably, x = 28, and the seedless form is likely to be triploid with 2n = 3x = 84, explaining the absence of seeds. To date there has been no deliberate breeding of breadfruit; only selection has been done by the farmers from seedling populations.

4.3.7 Major cultivars in Vietnam: No cultivar has been recorded in Vietnam.

4.3.8 Propagation: The seeded form of breadfruit is usually propagated by seed, while the seedless form by root suckers, although this method is rather unreliable and slow. Several other methods of vegetative propagation are possible, including grafting, but with varying degree of success.

4.3.9 Planting: Plants are set out in the field at the onset of the rains at a distance of 6 to 12 m, depending on the type and growing conditions. Partial shading is provided until the plants are well established. Often they are grown in household gardens or mixed orchards in Vietnam.

4.3.10 Pests and diseases: There are a number of diseases, including eight of economic importance: three root rots (Fusarium sp., Alternara sp. and Phillinus noxius), one crown rot, one leaf blotch (Phyllosticta artocarpicola), and three fruit rots (Rhizoctonia solani, Phytopthora palmivora and Rhizopus artocarpi). The fruit rot caused by Rhizopus artocarpi can be partially controlled with copper sprays. A few insects and mites may damage breadfruit trees, but can be chemically and biologically controlled.

4.3.11 Fruiting season: Fruits are harvested all year round.

4.3.12 Harvest and yield: Breadfruit trees typically yield well, but may suffer from drought when grown on porous coral soils in the Pacific, strong winds and salt spray damage. Artificial pollination, a relatively simple operation, has resulted in considerably increased fruit yields.

4.3.13 Post-harvest operations: Harvested fruits are collected in baskets and kept in cool place for 7 to 10 days. Fruits wrapped in polyethylene bags and kept at 12oC can be stored for about 20 days.

4.3.14 Problems: Breadfruit is still a minor crop in Vietnam. There is currently no varietal improvement, resulting in poor yield. There is very limited market for the fruit harvested.

4.3.15 Prospects: Breadfruit is an important staple food in many Pacific Islands countries as well as an exotic fruit of the western world.

4.4 Cashew Nut

(Anacardiaceae, 2n = 42)

4.4.1 Names:

Scientific: Anacardium occidentale Linn.


English: Cashew
French: Cajou, anacardier
Indonesia: Jambu Monyet (In), Jambu Mede (Jv)
Malaysia: Gajus, Jambu Monyet
Philippines: Kasoy, Balllubad (Ta), Balogo (Il)
Thai: Mamuang Himmaphan
Vietnam: Dao Lon Hot (North), Cay Dieu (South)

4.4.2 General: The cashew tree yields three products: an edible nut, an edible swollen pedicel (known as ‘apple’) and a phenolic liquid with industrial uses. The principal product, the kernel or nut, varies considerably in composition but is of high nutritional and calorific values. The nuts are a rich source of unsaturated fatty acids, calcium, iron, thiamine, riboflavin and nicotinamide. Cashew nut shell liquid (CNSL) obtained from the shell has numerous industrial uses, the main ones being for brake linings of motor vehicles and in paints, chemicals and plastics. The shells contain 20 to 25% CNSL of which 7 to 12% is commonly recovered, but only a small proportion of all cashew shells are used. The cashew ‘apple’ is the fleshy stem below the real fruit (‘nut’). It produces a gum used in vanishes (cashew gum), and is used as a table fruit or processed into pasta, jam, juice, beverages, vinegar, wine, candied fruit, etc. It is similar in composition to that of many other succulent fruits with a low calorific value, low protein and fat contents but has very high vitamin C content. Cashew nut ranks third after almonds and hazelnuts on the basis of total world production of tree nuts. Total world production was 700 000 t in 1996 while that of Vietnam was 122,000 t. Other major producers include India, Mozambique, Tanzania and Brazil.

In Vietnam, the area under cashew occupied only 30 000 ha in 1980, increased to 250 000 ha by 1996, and 300 000 ha in 2003. The total production in 1996 was 122 070 t, with an export value of $122.07 million for cashew kernel, making Vietnam one of the major producers of cashew in the world. At present, many provinces in the South including Dong Nai, Sing Be, Tay Ninh and Binh Thuan have large areas of cashew plantations.

4.4.3 Origin and distribution: The cashew originated in northeastern Brazil and spread in pre-Columbian times to large areas of South and Central America. The Portuguese and Spaniards took it to Africa and Asia in the 16th and 17th centuries, and later it reached northern Australia, Fiji, Hawaii and Florida. At present cashew is naturalized and cultivated in many tropical countries. It was introduced into Vietnam in the 19th century and originally grown in home gardens as a shade tree. It was recognized as an industrial crop only about 20 years ago.

4.4.4 Description: An evergreen, woody, much-branched tree up to 15 to 20 m tall. Leaves alternate, simple, glabrous, thick and leathery, oblong to obovate, 10 to 20 cm x 5 to 10 cm. The inflorescence is a panicle with numerous hermaphrodite or staminate flowers. Hermaphrodite flowers are usually terminal and borne on a short pedicel, with usually a superior, reniform, monocarpellate ovary. Staminate flowers are similar in structure to the perfect hermaphrodites, but are smaller, and with a sterile, rudimentary pistil. After fertilization, the ovary develops into one-seeded fruit, the receptacle swells and becomes a pseudo-fruit, called the ‘apple’. The fruits when mature are a kidney or heart-shaped achene, which are commonly, though incorrectly, called a nut of 3 x 2 x 1.2 cm and weighing 5 to 6g. The pericarp comprises a coriaceous epicarp, a spongy mesocarp containing aleveoles with a sticky, resinous liquid (CNSL) and a hard endocarp. The seed is slightly curved, consisting of a creamy white curved kernel covered by a thin, reddish-brown testa. The pseudo fruit or apple when ripe ranges in color from red to yellow, and is of variable shape and size.

4.4.5 Ecology: The cashew is sensitive to frost especially while young, and growth stops below 7°C. Growth is most rapid at an optimum monthly average temperature of 27°C. It needs a well-defined dry season of at least four months, and generally 1 000 to 2 000 mm per year over a 6 to 8 month period is suitable for commercial cultivation. Heavy rain during flowering or close to harvest is harmful. The cashew tree is regarded as very suitable for re-afforestation of poor, exhausted and eroded lands, although the best crops are produced on deep and fertile soils. In Vietnam, cashew-rowing areas are Quang Nam, Da Nang province and further to the south since these areas possess suitable soil and climatic conditions. Cashew is grown up to around 500 masl. in South Vietnam.

4.4.6 Genetics and improvement: The chromosome number of cashew is 2n = 42. Most plant improvement has been done by selecting seeds for planting from trees with desirable characteristics and on the basis of nut quality. The following criteria are used for selecting parent trees: dwarf, bushy, much-branched plant with many inflorescences and with a short flowering period (two to three weeks), a high percentage of perfect flowers, medium nut size, high shelling percentage, and a good quality of ‘apple’. The yields of cashew can be significantly increased through breeding and selection. Crosses between local and exotic cultivars normally exhibit hybrid vigor for yield, indicating the benefit of germplasm collection.

Major cultivars: Clonal selection has been made and many clones were released by MARD such as: DDH 66-14, DDH 67-15, B01, PN1, KP11, BD 01 (Hanoi 2004).

4.4.7 Propagation: Cashew is propagated by seed, which germinate within 15 to 25 days. The seedling populations are often highly heterogeneous and vegetative methods of propagation must be used to maintain the characteristics of selected trees. Various grafting and air layering technics are used to produce clonal trees which of course are more costly. Grafted trees begin to bear fruit after three years and reach full production after seven years.

In Vietnam, the most popular practice has been to select high-yielding trees and collect the seeds for planting. This method has led to low yield as most progenies from such trees were not true to type. However, since 1994, about 46% of new cashew plantations have been planted with selected grafted clones. Cleft grafting is recommended for propagation and the best time for grafting in Vietnam is from May to August.

4.4.8 Planting: In Vietnam, cashew trees are planted on degraded soils in the eastern and central coastal provinces of the South. Spacing is 10 x 5 m (200 trees/ha). Organic matter, for example farm manure, is normally applied at the rate of 10 to 20 kg/hole during planting time. No other cultural practice is carried out including fertilizer application and pruning since the income derived from cashew is very low. It is estimated that only 37.7% of the cashew plantations are provided with fertilizers that yielded on average 155 kg more than the unfertilized orchards (with an overall yield of 543 kg/ha) Robusta coffee or sometimes pepper and other fruit trees are planted with cashew in South Vietnam.

4.4.10 Pests and diseases: Anthracnose (Colletotrichum gloeosporioides) is a common and serious disease of cashew. Water-soaked lesion develops on affected shoots, inflorescence and fruits, resulting in dieback and finally death of the whole tree. Fungicide sprays can be used as a control. Major insect pests include an East African weevil (Mecocorynus loripes) the larvae of which make extensive tunnels in the trees, an Indian weevil (Plocaederus ferrugineus) with wood-boring grubs, and a Brazilian butterfly (Anthustarcha binocularis) with larvae boring into young twigs and inflorescence. General control measures include plant and plantation sanitation and the use of insect repellents and insecticides.

Shoot borer (Zeuzera coffeae) is the most serious pest of cashew trees. Control measures applied for pests and diseases were practiced only in 2.17% of orchards.

4.4.11 Fruiting season: All year round.

4.4.12 Harvesting and yield: As most orchards in Vietnam were planted with low-yielding material and poorly managed, the average yields are as low as 500 to 600 kg/ha/yr. However, recent development has resulted in average yield of 2 000 kg/ha/year with newly selected clones. Good, well-managed cashews should yield up to 4 t/ha of kernels. The size of many Vietnamese cashew kernels is also often below accepted standard and market acceptance is a problem for the growers.

4.4.13 Post-harvest operations: After being roasted in oil, the nut is cracked with a wooden mallet or opened with a special opening sprader device. Raw nuts are sometimes slit open with a knife or spreader, but great care jas to be taken to avoid the highly corrosive CNSL. Small-scale factories are suitable for a newly producing country like Vietnam because of the relatively small quantity of nuts grown, and low labour cost rates.

4.4.14 Problems: Most cashew trees grown in Vietnam are unimproved cultivars giving low yield and quality. There is no breeding programme or germplasm collection for cashew in Vietnam. Being a low-income crop no extra input is provided. Major constraints in cashew production in Vietnam are lack of: (i) planted improved cultivars, (ii) sufficient high-quality planting material, and (iii) interest by the government as compared to other industrial crops such as cotton, rubber, etc.

4.4.15 Prospects: Being one of the most drought and poor soil tolerant crops, cashew has a role to play in being cultivated in this degraded soil. As there is an increasing trend in world demand, there is a good prospect for Vietnam to expand plantings of cashew, together with processing facilities to produce good quality cashew for export market. Vietnam already is able to produce some high quality cashews, as evidenced by the high quality cashew nut products available at airports and in the Hho Chi Minh City and Hanoi markets and 90% of the production is exported. Viet Nam is exporting s cashew nuts to the USA, Australia, the Netherlands, and China.

4.5 Dragon Fruit

4.5.1 Names:

Scientific: Hylocereus undatus (Haw) Brit. & Rose


English: Dragon fruit
French: -
Indonesia: -
Malaysia: -
Philippines: -
Thai: Kaeo Mangkon, Luk Mangkon
Vietnam: (Cay) Thanh Long

4.5.2 General: The fruits, having very attractive color and shape similar to the eyes of the imaginary animal, the dragon, have been quite popular in Vietnam under the name of ‘dragon’s eyes’ or ‘thanh long’. In addition to its attractive color and shape, the dragon fruits also have a high nutritional value including vitamin C, calcium, potassium and fiber. They are claimed to reduce cholesterol that is the cause of coronary heart disease. As it helps the digestive system and also prevents cancer, the fruit is considered by some as a health fruit. Until recently, Vietnam was the only country in Asia producing dragon fruits on a commercial scale, exporting to Hong Kong, Singapore, Malaysia, China, Taiwan, Japan and EU. Main production areas in Vietnam are: Binh Thuan, Lon An, Tien Giang.

4.5.3 Origin and distribution: Originating in Central America, the dragon fruit plants were brought to Vietnam about 50 years ago. It is commonly cultivated in Vietnam and a few other countries like Southern China and recently in Thailand, Australia and Taiwan.

4.5.4 Description: A plant belonging to the cactus family, resembles other cactus in being three sided, winged with a fragmented viny stem (similar to the fin of the dragon). The plant climbs on any type of support - other trees, walls, a trellis etc.. At each node, there is no leaf (like the other cactus plants), but instead, a group of 4 to 5 spines attached to the stem. The fruit is egg-shaped about 7 to 10 cm wide, 10 to 15 cm long and weighs 300 to 700 g. The skin is leathery, thin (2 to 3 cm), brilliant reddish color with several greenish, soft flat scales protruding out towards the end of the fruit. The flesh is pure white, soft, juicy with numerous small black seeds. Both the flesh and seeds are edible with a pleasant mild sweet/sour taste and characteristic aroma making it pleasant to eat especially during hot weather.

4.5.5 Ecology: Although dragon fruit grows in any soil types and is quite drought resistant, it prefers well-drained soils with pH of 6.3 to 6.8 and soils high in organic matter. It needs bright sunshine. Rainfall should not be more than 2500 mm per year.

4.5.6 Genetics and improvement: Other species of Hylocereus include: H. polyrhizus, H. costariciensis and another unidentified species, all of which produce edible fruits but smaller in size that H. undatus.

4.5.7 Major cultivars in Vietnam: Two cultivars, namely Binh Thuan and Cho Gao, are commonly grown in Vietnam. SOFRI has successfully bred the red-fleshed cultivar with the local ones, resulting in some outstanding clones of red-fleshed dragon fruit. It is expected this red-fleshed cultivar will be released for production within two years.

4.5.8 Propagation: Dragon-fruit plant can be propagated by seed but the most practical method is by cutting. The stem to be used for propagation should be more than one-year old. A cut stem section of 20 cm is inserted in the propagating medium - sand, burned rice husk, or potting soil. Rooting hormone is not necessary as the cutting develops roots easily in about 30 to 45 days and is ready for transplanting.

4.5.9 Planting: To obtain optimal yield and quality, the dragon plant should be grown in fertile soil with irrigation.. A trellis can be constructed in the following manner. Take a 2.5 m long cement post and embed one end 0.5m in the soil. On the top of the post, attach a wooden crosspiece to support the vines of the plant. Normally, four plants are grown at each post, one on each side of the post. Dig each hole for the plant 30 x 30 x 30cm add manure and compost to the soil and plant. Spacing between is 3 x 3 m. In lowland areas, good drainage should be provided during the rainy season since the root system of the dragon plant is susceptible to waterlogging. During the first year, water regularly (about once every five to seven days) but take care not to over-water. Control weeds and apply mulch. Chemical fertilizer at a rate of 15-15-15, 1 kg/post (of four plants), should be split into six applications, during the first year. In years 2 to 3, more manure and/or compost, and fertilizer (15-15-15, 8-24-24, or 19-20-26) should also be applied in order to provide enough nutrient for the growing dragon plants.

4.5.10 Pests and diseases: Dragon-fruit plants do not seem to be susceptible to pests and diseases. Only minor pests are encountered - aphid (Pentalonia nigronervosa), mealy bug (Pseducoccus brevipes) and ants (Solenopsis geminata, Iriidomyrmex humilis and Pheidole megacephala) which can be easily controlled by common insecticides. Collar rot (Phytopthora sp.) and root rots (Fusarium sp., Alternara sp.) are the two main diseases, which can be controlled by fungicides. Weeds are normally controlled manually, and the residue is to be left to cover the hole as mulch.

4.5.11 Fruiting season: Dragon fruit plants produce fruits almost all year round, especially if irrigation and fertilizer are provided. Timing of fruit ripening to satisfy the market demand at particular period can be done by providing additional light during the short-day period to induce flowering at the required period.

4.5.12 Harvesting and yield: Harvesting is done by manually picking each mature fruit. Dragon plant is a high yielder, with a yield of 50 to 80 t/ha, provided good cultural practices are adopted.

4.5.13 Post-harvest operations: Being a delicate fruit, care must be taken in handling the transport of fruits from the farm to the market. Special care is provided in the packing for the export market, where special cartons are used. The fruits keep well in the refrigerator, and in fact, the quality improves after storage. If consumed right after picking, the fruit is a little sour, but sweetens after keeping a few days.

4.5.14 Problems: The fruit is not well known in other countries so the export market is limited. At present, there is an improvement program to develop new cultivars of the dragon fruit as well as an international project for pest and disease identification on this crop. However, the existing dragon fruit cultivars are good, having high quality and accepted by the cosummers; thus this is not a major constraint..

4.5.15 Prospects: Having attractive color and shape, supplemented with high nutritional value and pleasant taste and aroma, dragon fruits have great potential as export commodity to countries like China. At present Vietnam exports dragon fruits to several nearby countries particularly Hong Kong and Singapore. It has great potential to be exported to European markets as its taste is liked by Europeans. It has less sugar content than most popular tropical fruits, and thus is more suitable to diabetics and high blood pressure patients. In very near future, the red-fleshed cultivars having high sweetness, hight vitamin A and self polination of flowering, will be released.

4.6 Mangosteen

(Guttiferae, 2n = 56-76, 88-90, 96, and 120-130)

4.6.1 Names:

Scientific: Garcinia mangostana Linn.


English: Mangosteen (En)
French: Mangoustan
Indonesia: Manggis
Malaysia: Manggis
Philippines: Manggustan, Manggis
Thailand: Mangkhut
Vietnam: Mang Cut

4.6.2 General: Main production areas in Vietnam are: Binh Duong, Ben Tre, Can Tho and Hue.

4.6.3 Origin and distribution: At present mangosteen is only known as a cultivated species since no wild form exists. It is cultivated mainly in SE Asia where it originated. Other countries like Sri Lanka, South India, Central America, Brazil and Queensland (Australia) have only small areas of production

4.6.4 Description: Mangosteen is a medium-sized tree, 8 to 10 m tall, but it may reach 20 m or more if growing conditions are suitable. It has a straight trunk and is symmetrically branched to form a regular pyramidal crown. All parts of plant exude yellow latex when damaged. Flowers are borne singly or in pairs at the apex of branchlets. Fruit are globose, smooth, turning dark purple when ripe, with persistent sepals and still crowned by the stigma lobes. The purple 1-cm thick rind encloses white arils of three to seven segments. The aril or flesh of mangosteen is considered to be the best tasting fruit of all, by some people.

4.6.5 Ecology: Mangosteen will only grow in the humid tropics and is often found in association with durian. (There is a saying that durian is king of fruits and mangosteen is queen of fruits. King and queen of fruits always stay together, in the natural condition or on the table). It thrives well only under high temperature and rainfall. Shade is required during the young stage when growth is very slow, but after two years, the trees need direct sunlight.

4.6.6 Genetics and improvement: Being a monotypic species, there has been little or no known natural genetic improvement via hybridization in mangosteen. Embryo rescue tissue culture techniques and mutation induction are ways that mangosteen may be improved.

4.6.7 Major cultivars in Vietnam: Mangosteen is monotypic, i.e. there is no variation because it is propagated apomictically (through the development of maternal tissue). Thus all mangosteens in the world are of only one cultivar. Variation that is observed is mainly caused by environmental factors. However, Vietnam is now conducting a clonal selection programme with the hope to obtain better mangosteen clones.

4.6.8 Propagation: The only way to propagate mangosteen is by seed that produces a true-to-type seedling. Growth is very slow taking up to two years before the seedling is large enough (60 cm) to plant out in the field. However, grafting has been attempted with some success, and in Australia, special nursery management techniques have been developed to accelerate seedling growth rates to shorten the long juvenile phase of 8-10 years before fruits start to bear. However, with good planting materials, and under proper irrigation and fertilization, the mangosteen trees can give first fruits at six years after planting

4.6.9 Planting: Mangosteen requires nurse trees or artificial shade to shade the young plants, thus it is a common practice to grow mangosteen together with other fruit trees like durian, langsat, rambutan or coconut. Mangosteen requires an area of 40 to 80 m2 per tree for growth.

4.6.10 Pests and diseases: No serious pests and diseases are encountered in mangosteen. A physical injury to the fruit causes the yellow latex, known chemically as gamboge, to exude from the latex vessels of every part of the plant including the fruit. This injury may also bring about the hardening of the rind and the fruits become difficult to break open, while the flesh inside deteriorates. However, boron deficiency is a very likely cause of this rind hardening and internal corking and breakdown.

4.6.11 Fruiting season: In the South of Vietnam, May to August (peak period June to July). while in Central Vietnam (Hue), mangosteen bears fruit in January-February.

4.6.12 Harvesting and yield: Mangosteen has a very long juvenile phase of growth before cropping begins and this is usually eight to ten years and this is a major deterrent to many farmers. Mature fruits should be picked every two to three days before they become over ripe. Only the fruit that have turned from greenish to light red color should be picked. It is difficult to obtain yield data as most mangosteen orchards are not pure stand, but consist of many kinds of fruit tree. From 200-2 000 fruits may be obtained from a single tree, or the average of about 400 fruits/tree, equivalent to a yield of 4.5 t/ha.

4.6.13 Post-harvest operations: Light red fruit ripens in four to six days. At the end of this stage, the fruit turns to dark purple that is a sign of the full ripe stage. Ripe fruit have a shelflife of about one week. The fruit is graded by size and appearance of the skin. In spite of having thick skin, mangosteen fruit is very delicate and vulnerable to physical injury. Even one drop of the fruit from 10 cm high will cause internal damage. Hence the fruit should be handled with extreme care from harvest to marketing.

4.6.14 Problems: Since mangosteen thrives only in strictly humid tropical conditions, and any slight change in the climate may affect productivity, it is difficult to a maintain mangosteen orchard, unless great care is taken in management. Picking is also very costly, and so are handling and transport.

As it normally takes 10-15 years for trees to come into bearing, it is difficult for any new growers to decide to grow mangosteen. A long juvenile phase, before fruiting of eight to ten years is a major deterrent to larger scale production. However, if the plant is well taken care of, fruiting can start at 6-7 years after planting

4.6.15 Prospects: Considered as perhaps one of the the most delicious fruits of all, mangosteen has an excellent prospect for both domestic and export markets, provided that quality of fruits can be maintained at all stages. Vietnam has excellent opportunities for expanding production.

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