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INTRODUCTION
The rambutan (Nephelium lappaceum Linn.) is indigenous to the Malay Archipelago and is a fruit of widespread popularity in Peninsular Malaysia. Like most other tree fruits, the cultivation of this popular fruit is predominantly undertaken by smallholders who grow the plant in mixed orchards or holdings called 'dasun' which are scattered in kampungs throughout the country. As such, formal cultivation of this fruit with proper cultural practices have not been seriously attempted until very recently. This has been due partly also to the lack of information on the correct method of propagation, establishment and maintenance. There has been increasing incentive among some individual growers recently to plant this fruit tree in sole orchards on large scale basis. It was estimated that of the total physical hectarage of 10,761 hectares (based on total sole crop equivalent) in 1976, about 16 percent was planted in mono crop orchards. With the increasing interest, it is possible that the present area under this fruit should considerably exceed the above estimated hectarage.

By and large, a great proportion of the rambutan grown in the country is consumed fresh or raw. A small amount is made into jam for home consumption. The possibility of commercialising this home-made jam has not been studied and attempted. Quite a substantial amount of the fruit is now available in canned form and is well received by the public. The feasibility of canning rambutan will, admittedly, generate greater demand for this fruit. It is envisaged that the area under this fruit will increase substantially in the next few years. However, canning quality and potential is restricted to only a few clones. Thus the increase in hectarage envisaged will be confined to a few distinct and acceptable clones at the expense of the less important ones.

SOIL REQUIREMENTS

The distribution of rambutan in Peninsular Malaysia corresponds closely with that of the durian. Hence, like the durian, it is also adapted to a wide range of soils. It has been observed to thrive best on soils derived from granite like the Rengam series. Observation has also shown that even poor soils like the Batu Enam series are capable of supporting a reasonably good crop. Only the peats, poorly-drained and very sandy soils are unsuitable, as the rambutan tree does not thrive well on these soils. Generally, the best soils appear to be those which are deep, loamy, well-drained and with high organic matter content. However, unlike the durian, rambutan does not grow vigorously on steeper slope. The maximum limit is about 12° slope.

The selection and preparation of site for planting, both for small and large scale planting, are similar in many ways to that proposed for durian.

CULTIVARS (CLONES)

A large number of rambutan clones is available in the country, each differing from the others in several distinct ways. However, not all of these are recommended for general planting. Even some of those recommended earlier have proved obsolete against the test of time. Recommendation of clones for planting is made complicated by the inevitable effects of the environment, as some clones are specific and perform well in one environment or area but not in other areas. Thus, some of the clones reported to be promising in one area may be frowned upon by growers who plant them in a different area. Nevertheless, from the collection of the 'older' clones of rambutan that have been tested in Serdang, eight have been recommended for general planting. These are: R3, R4, R7, R9, R99, R134, R139. The latter three are recent additions. Of these, R134 has proved to be a reliable clone in Serdang. It appears to be an early-season clone, coming into bearing earlier than the others. The fruit is large and the flesh is firm. R137 and R139 are good-yielding clones which produce fruits of above average quality. In addition to the above, a few other promising clones may also be cited. Among these are R156 (Muar Gading) and R168 (Cik Embong).

PROPAGATION

The rambutan is widely, though not advisedly, raised from seed, since this is the easiest method of propagation. A large proportion of stands that exist in the mixed holdings in the country at the moment are seedling trees. This method of propagation is no longer favoured and recommended.

The most common method of propagation now is by bud-grafting. It has the advantage over the seed propagation in that it gives true-to-type individuals and the plants propagated this way often come into bearing much earlier. In bud-grafting method, the rootstocks can be raised from seeds of fruits available in the markets. They are ready to bud when they have attained a diameter of 0.5 to 0.75 inches (about pencil size) and producing a new flush of leaves. The best sources of budwood are trees that are known to be good bearers of high quality fruits, but which have borne little fruits in the current season. Shoots selected for budwood should be well furnished with dormant buds and should be obtained from trees three to four months after harvest, since at this time the bark will part easily from the wood. The success of 'take' is affected by the weather. Bud-grafting succeeds best in dull, cloudy weather. After the bud patch has been fitted, it is tied using transparent, clear plastic strip. About 18 to 20 days after budding, the bud-patch is checked. If it remains green, which indicates successful 'take', the stock may be cut back to within six inches of the bud about seven to ten days later to encourage the bud to develop. Plants with vigorous shoots can be transplanted about two to three months after the bud starts to grow. Normally, the total time from budding to the production of a plant large enough for planting out is about four to five months.

Other methods of propagation such as approach grafting or inarching and air layering or marcotting have not been looked into at great depth and are seldom practised.

PLANTING

Planting systems:
Three planting systems are commonly adopted. These are (i) the square planting system, (ii) the quincunx planting system, and (iii) the triangular planting system. A fourth planting system, namely, contour planting system, is commonly adopted when planting trees on undulating or sloping land. The number of trees per acre (i.e. planting density) will vary according to the system adopted and also the planting distance that one chooses. A planting distance of 30 ft x 30 ft is normally used.

Planting holes:
Planting holes should be dug to a minimum of 2 ft x 2 ft x 2 ft. Large and deeper holes are better. In making holes, the top soil should be set aside in separate heap and later mixed with 25 to 30 1bs of dried and decomposed cattle dung or other animal manures. The mixture is then put back into the hole, firmed, and the level of the soil in the hole area raised to about six to nine inches to allow for subsequent sinking.

Planting:
The best time for planting is during the onset of the rainy season. The moist, but not too wet, showery weather with overcast cloudy sky would be most ideal for plant establishment. The young tree may be planted out on the field about a week or two after the hole has been prepared. Care must be taken not to allow the roots of the young plant to dry out. For this reason, it is advisable to water the plant in the polybag before taking it out to the field for planting. When planting, a hole is dug in the centre of the prepared planting hole in accordance to the size of the po1ybag or the plant. The po1ybag is then removed with as little disturbance to the roots and soil as possible. It is then placed in the cavity and covered with soil. The soil around the plant should slope slightly from the plant to the sides of the hole to provide drainage.

APPENDIX 1
RAMBUTAN MANURING SCHEDULE

Shade:
The young plant must be provided with shade to protect it from strong sunlight. Temporary shade may be provided by making use of a few palm leaves. These leaves are simply placed firmly on to the ground around the plant with their tops meeting above the plant. These temporary shade should be provided for the period of from two weeks to a few months to enable the plant to recover from transplanting shock. This may be gradually removed, after which the plant is left to be shaded by 'permanent' shade, which is best provided by banana plants. Apart from providing 'permanent' shade, the banana also allows for maximum utilization of the land and provide side income to the grower.

Staking:
Staking is simply putting a support to the young plant. This is best done by driving a stake into the ground near the young tree and then tying them together with a soft rope or string.

FIELD MANAGEMENT

Mulching:
Mulching is done as soon as the plant has been planted on the field. Mulching serves two purposes, namely preventing the growth of weeds near the plant as well as keeping the soil cool and at the same time conserving moisture around the base of the tree. Mulching materials can be provided by organic matter such as straw, dried leaves or grass cuttings. Coconut husks may also be used.

Fertilizer and manuring:
It is important to adopt a consistent and well-balanced fertilizer and manuring programme in order to stimulate rapid growth in the young trees as well as to ensure maximum yield at the bearing stage.

As mentioned earlier, at planting stage, 8 oz of rock phosphate mixed with 25 to 30 lbs of dried cattle dung is normally incorporated with the soil and put into the planting hole. The amount and time of subsequent fertilizer application are as shown in Appendix 1. As in the case of other crops, fertilizers are normally applied either as broadcast or in narrow band around the periphery of the canopy at the base of the tree.

Pruning:
Pruning aims at maintaining good vigour of the tree, obtaining desired shape of canopy and to enhance production of fruits. The operation, as usual, consists of removal of dead, broken or diseased branches and water shoots. Removal of these unwanted parts permit free circulation of air and allows good penetration of sunlight through the canopy. In rambutan, open centre system of pruning is recommended. In carrying out pruning, a balance must be struck between fruit development and vegetative growth, as it is certainly unwise to cut off potential bearing shoots or branches. All wounds due to pruning should be pared with sharp knife and later painted with tree dressing. The removed parts must be burnt.

Weeding:
Weeding is carried out to remove other plants which tend to compete with the tree for sunlight and nutrient. The operation may be done manually or with the help of machinery. If mulching has been successfully carried out around the base of the tree, circle weeding, which justifiably should be done manually, may not be necessary at all. Weeding with machinery should be confined to the inter-row or inter-plant spacing. However, if the spacings are filled with good and vigorous legume covers, service-cutting to clear weed may not be necessary. Spots of Ialang are easily eradicated with the help of Roundup, while general weeds are easily controlled by spraying with Gramoxone or other recommended herbicides.

Pest and disease control:
The rambutan is free from many pests and diseases. The major pest appears to be leaf-eaters, which attack and feed on young developing shoots. The best control measures appear to be spraying with suitable systemic insecticide. These leaf-eaters are not particularly serious once the plant is well-established.

DATE: May 1984

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