Although a large proportion of the fruit trees grown West Africa are grown on a domestic scale, the number of commercial holdings with fruit trees is gradually increasing. There is a constant demand for fruits such as citrus and pineapples which can be processed to produce a range of products which can be bottled or canned. Other fruit products are potentially export commodities, but the main production of locally grown fruit and nuts is required for domestic con-symptom.
The following are the main characteristics of fruits and nuts grown in West Africa, including: avocado pear, banana, citrus, mango, jackfruit, paw-paw, pineapple and cashew.
Fruit Trees: The soil and fertiliser requirements of tree crops have already been described in and propagation, nursery operations and transplanting have been dealt with in earlier sections of this chapter. The cultural and environmental characteristics of the crops referred to in Table are as follows.
The following are the main characteristics of fruits and nuts grown in West Africa, including: avocado pear, banana, citrus, mango, jackfruit, paw-paw, pineapple and cashew.
Fruit Trees: The soil and fertiliser requirements of tree crops have already been described in and propagation, nursery operations and transplanting have been dealt with in earlier sections of this chapter. The cultural and environmental characteristics of the crops referred to in Table are as follows.
The fruit of this tree is extremely nutritious since it has a high fat content, in addition to valuable vitamin and minerals. Seedlings, budded or grafted plants should be established in well-drained soils with a good organic content since avocados are sensitive to excessive soil moisture. They are, however, also sensitive to very dry conditions. Young trees require water in the first and possibly second dry season after planting.
Many cultivars are available, some with different periods of maturity which can be planted to extend the fruiting season. Spraying will control most of the pests of avocado, diseases are rare except for 'die-back' which may be caused by very dry root conditions.
Fertiliser should be applied if rapid and vigorous growth is to be obtained.
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Bananas: These are widely planted throughout West Africa, but since they require moist, fairly rich soils, their distribution is limited to the areas with soils which retain water. They do not thrive at elevations over 1,200m since bananas also have a requirement for stable and fairly high temperatures with a relatively high humidity; they are therefore most widely grown in the forest areas. Propagation is by means of young basal shoots or suckers which are separated from the parent plant and established in well prepared planting holes.
Irrigation is also required in the dry season after planting and fertiliser should be applied to maintain vigorous growth. Bananas are often grown on ridges, particularly if the area is likely to be flooded during heavy rainfall. Mulching may be applied during the dry season, to retain soil moistures.
Diseases and pests may be serious and bananas should not be replanted on the same soil at intervals of less than 4 years to avoid nematode infestation. A regular spraying programme will control most diseases and pests. Many cultivars are available, including Dwarf Cavendish selections, Poyo,Lacatan, Gros Michel and many others, including local selections.
Citrus: These fruits provide a valuable source of vitamins and various kinds of citrus such as lime, orange, grapefruit, tangerine and lemon are grown in many parts of West Africa. They do not thrive in the very wet areas, due to the incidence of pests and diseases, but give good yields at higher elevations where the rainfall is over 150 cm per annum. The several cultivars of each type of citrus which are in cultivation also have varying responses to the environment but, in general, all citrus require a fertile, deep soil, well supplied with organic material and with a good moisture retaining capacity. Fertilisers are required if maximum yields are to be obtained and irrigation may be needed during dry weather, particularly during the first two years after planting.
Propagation is by budding and rough lemon, sour orange and Cleopatra mandarins are used as stocks In high rainfall areas, budding at a height of at least 40 cm is practised, to avoid gummosis, a fungal disease. Where Tristeza virus occurs, Cleopatra mandarine is preferred as a stock, since it is partially resistant to this virus. Budded plants from the nursery are planted out, when the scion has become
well developed, to well prepared planting holes. Stakes are often necessary and some shade may be required until the trees have recovered from transplanting.
Diseases and pests may be kept in check by using a regular spraying programme; citrus scab can be very serious, particularly in high rainfall areas and should be controlled by using a copper-based fungicide.
Mulching during both the dry and wet seasons is recommended for all kinds of citrus.
Guava: This fruit is propagated by seed obtained from high yielding parent trees, the seedlings are raised in nursery conditions and transplanted when about 50 cm high to well prepared planting holes. Irrigation during the first two dry seasons after planting, mulching and occasional fertiliser applications are the main cultural requirements. Two main types are grown, the red and the white skinned, both of which are high in vitamin C content.
Mango: The mango, when fully developed, is a large tree and a generous allowance for later development should be made when planting. Many cultivars are now commonly cultivated, most of the newer ones are high yielding and produce good quality fruit. Mangoes are propagated by budding, more rarely by approach grafting, and budded plants are normally established In their permanent positions when about 18 months old. Well prepared planting holes are essential and irrigation may be required until the trees are well established. Although mangoes are tolerant to a wide range of soil conditions, occasional fertiliser will promote maximum growth. Routine cultivations include mulching and pruning of crossing or dead wood. Rain during the flowering period can reduce yields.
Pests and diseases are rarely serious.
Jackfruit: Jackfruit fruit is most commonly cultivated in areas of fairly moderate to high rainfall and is similar in its requirements to breadfruit and breadnut although it has a large dark green oval leaf which is not divided.
The large elongated fruits are produced directly from the main trunk of the tree and trees may grow to a height of 12-15 m. Propagation is by seeds and although tolerant to a wide range of soils, these should be generally moist and have a good organic content.
Pawpaw: This is a short ,lived fruit tree which is usually dioecious that is, the male and female flowers are unisexual and are produced on separate plants. One male tree to 5-6 female trees will ensure adequate fertilisation. Seedlings are difficult to identify as either male or female and it is usual to uproot and replant male trees which are unwanted. Some newer cultivars are monoecious, that is they have male and female flowers on the same plant.
Paw-paws are raised from seed in the nursery in containers and transplanted to permanent positions when about 30 cm in height. Weeds should be controlled and the plants are mulched and irrigated during the dry season until established. Pests and diseases can be controlled by spraying, except for virus diseases; infected plants should be removed and burned.
Pineapple: Many cultivars of pineapple are grown in various areas but some of the more recently introduced ones have high quality fruits and are preferred for both local consumption and canning. Closely spaced plants produce smaller fruits than those which are more widely spaced and if fruits are required for local consumption, wider spacings are preferable.
Propagation is from crown suckers, basal suckers from the base of the fruit, or slips which are obtained from shoots produced from the lower part of the stem. Slips produce fruits more rapidly e.g. in 9-12 months, than other types of cutting but cuttings of all types should be rooted in nursery conditions before being planted out in either single or double rows. Pineapples respond well to fertiliser but excess nitrogenous fertilisers may induce the production of large coarse fruits. Pineapples are partly droughts resistant but initial irrigation after planting, until the roots are well established, is recommended. Weeds should be controlled and pests and diseases controlled by spraying.
Cashew Nut: Cashews are partly droughts resistant and require little attention after establishment except for weeding, mulching and occasional fertiliser application. The seeds are normally sown in nursery conditions and the seedlings transplanted when about 40 cm high. Pests and diseases are rarely serious. Several cultivars are grown in West Africa, some have a red, others a white aril or succulent fleshy attachment to the seed.