Though cocoa has been known as the beverage crop even before tea or coffee, it is relatively a new crop in India. The cultivation of cocoa in India on a large scale started in the early 1970s. Eighty per cent of the cocoa area is inter-planted in coconut and areca nut gardens. It is also grown as an under crop in partially cleared forests. From imports of about 1000 tons in early 70’s our country has exported about 148 tons of beans in 1985-86. The present area under cocoa is estimated to be around 22600 ha. With a production of about 6300 tons. Kerala accounts for 79 per cent of the area and 71 % of the production of cocoa. Karnataka ranks second with an estimated 18 per cent of the area and 25 per cent of production.
Though cocoa (Theobroma cacao L.) is a native of the Amazon region of South America, the bulk of it is produced in the tropical areas of the African continent. About 35 countries in “the world produce and export cocoa, the major producing countries being Ghana. Nigeria. Ivory Coast. Brazil and Cameroon. In 1985-86 the total world production was 19&8 thousand metric tons.
Scientific name-Theobroma cacao.
Climate and soil required for cocoa cultivation-
Cocoa is a crop of the tropics. Though the crop grows between 200N and 200S latitude, the main growing areas are situated within 10° north and south of the equator. Cocoa is grown from sea level up to an elevation of about 500m. However. It comes up best up to 300m above sea level. Ideally. Cocoa requires a minimum 90-100mm rainfall per month with an annual precipitation of 1500-2000mm. Rainfall can be supplemented with irrigation during the dry periods.
Cocoa needs an equitable climate. It grows within a range of 15°-39°C and temperatur~ around 25°C is considered the most optimum. It cannot be grown commercially in areas where the minimum temperature falls below 10°C, and the annual average temperature is less than 21°C. The microclimatic environment around the cocoa plants consists of a high humidity at all times.
Cocoa requires a soil which can be easily penetrated by its roots. Retains moisture during the dry season and permits the movement of air. Poorly drained soils are inimical to this crop. A significant proportion of the cocoa of the world is grown on clay loams. Loams and sandy loams. It thrives on a wide range of soil types with pH ranging from 4 .5-8.0 with the optimum pH being 6.5-7.0. Cocoa does not come up in coastal sandy soils where coconuts flourish.
The cocoa whose natural environment is the lower storeys of the forest. Requires shade when young and also to a lesser extent when grown up. Young cocoa plants grow best with 50% full sunlight. It grows very well in the partially shaded conditions prevailing in the areca nut and coconut gardens in our country. As the tree matures. Its shade requirements are reduced.
Varieties of Cocoa beans-
Commercial cocoa has two major varieties. Criollo and Forestero which differ mainly in the color of the cotyledons. Criollo cotyledons are plumpy and white when fresh. turning cinnamon colored on fermentation.In Forestero the beans are flat and the color changes from purple when fresh to dark chocolate brown on fermentation. The dark red Criollo pods have a rough surface. pronounced point and a thin wall wihle Forestero pods are green when immature and yellow when ripe. thick walled. melon shaped with rounded ends and smooth inconspicuous ridges. The Criollo variety possesses a bland flavor and pleasant aroma. while
The Criollo variety possesses a bland flavor and pleasant aroma. while Forestero variety possesses a harsh flavor with bitter taste. In India. the Forestero variety is recommended for cultivation. The Criollo variety has a lower adaptability and less yield potential. It is highly susceptible to diseases. Hence its cultivation is not enouraged anywhere in the world . Forestero variety forms most of the commercial Cocoa of the world. Criollo ferments fully in three days, while forestero variety needs six days. They must, therefore; be fermented separately.
High yielding accessions:
The accession numbers of I-21. II-11. II-18, II-67. III-5 and III-101 from Malaysian collections were found to be high yielders compared to other types. These selections have got desirable characters such as high yield and more than one gm. Bean weight. These accessions are. Therefore, recommended for the cocoa growers for cultivation.
Raising of planting material in Cocoa-
1.Selection of seeds:
Cocoa can be propagated from seeds. or vegetatively from buds and cuttings. However, vegetative propagation is used only for experimental studies. Fresh beans should be used for sowing. as cocoa seeds lose their viability soon after they are taken out of pods.
2. Nursery techniques:
Before sowing. the seeds are rubbed with dry sand or wood ash to remove mucilage. The beans are planted with their pointed end upwards . Seeds may be sown either in plastic bags (25 x IS cm size. ISO gauge) or in raised beds. If planted in beds. young seedlings are usually transplanted into polythene bagsa.fter about two weeks of germination. The seedlings are ready for transplantation to the field after about 3-4 months. In tropical West Africa. seeds are often sown in situ instead of transplanting the seedlings . In such a case. two seeds are planted per pit and the weaker seedlings are later thinned out.
As cocoa shows considerable variability in the field. it is recommended that seedlings may be obtained only from government nurseries and such other dependable sources.
3. Vegetative propagation:
Vegetatively propagated progenies will be true to the parents. Soft wood grafting is found to be possible in cocoa. The method consists of cleft grafting of scions to the seedlings of 40-45 days old raised in polybags. The scions are procured by prior defoliation of shoots of comparative thickness. The scions start sprouting within one month. All the shoots emerging from the root stocks are to be removed periodically. The grafts are planted in the pits as in the case of seedlings. For better establishment, greater care has to be exercised by providing water. shade and nutrients.
Establishing plantation of cocoa-
As a pure plantation. Cocoa can be planted in forest lands by thinning ‘and regulating the shade suitably. It is planted at a distance of 2.5-3.0 m both between and within rows, either at the beginning of the monsoon. In May-June. Or at the end of the monsoon, in September.
Spacing and alignment:
Cocoa seedlings are planted in pits of 75 cm cube filled with compost. It can be planted with advantage as a mixed crop with both areca nut and coconut. The mixed plantations of areca nut and cocoa can be raised adopting either the quincunx method at a spacing of 4m x 4m with the cocoa occupying the centre of the square, or the normal spacing of 2.7mx 2 .7m for areca and 2 .7m x 5.4m for cocoa . Both areca and cocoa require shade during the first two hot weather seasons after planting . Banana can be grown as shade crop. Red gram. Sesbania and such other tall growing pulse or green manure crops are found to be equally good. All of them may be planted either within or bet\veen rows. During the subsequent years, the shade cast by areca palms will provide the required shade for cocoa. When cocoa is to be raised as a mixed crop with coconut, either Single hedge or double hedge system of planting may be adopted. In single hedge system cocoa can be planted 2.7m apart in a single row in between two rows of coconut, while in double hedge system it can be planted 2.5m apart in double rows in between two rows of coconut palms.
Manuring and irrigation:
An annual application of 100g N, 40g P20S and 140g K20 per tree per year in two equal split doses is recommended. During the first year of planting the plants may be given one-third the above dose. while in the second and third year two-thirds and full dose of fertilizers applied. The fertilizer is applied in two splits. the first dose in February-March and the second dose in September-October. fertilizers may be applied uniformly around the base of the tree up to a radius of 75 cm and forked and incorporated into the soil. Summer irrigation is one of the important aspects of the cocoa cultivation. Cocoa plants require a continuous supply of moisture for optimum growth and yield. During summer. the plants will have to be irrigated at weekly intervals. When cocoa is planted as a mixed crop in areca nut garden it has to be irrigated with 30mm depth of water with IW/CP ratio of 1. If adequate water supply is not ensured in summer months. the yield will be reduced and under mixed cropping systems if there is severe drought. the yield of both the Crops may be affected. Providing adequate irrigation is very important for cocoa both in mono as well as mixed crop system.
The cocoa trees should be pruned regularly to develop a good shape. For this all the fan branches arising from the main stem are nipped off up to a height of about 1.0-1. 5m or cut in the initial years of their growth. Later. only the thin and dried up branches are periodically removed. Operations like harvesting, spraying etc. will be easier if the height of the trees is kept at the second storey level.Cocoa grows in a series of storeys. The chupon or vertical growth of the seedlings terminates at the jorquette. where four or five fan branches develop. Further chupon develops just below the jorquette and continues its vertical growth till another jorquette form and so on.Then the first jorquette develops at a height of about 1.5 m. the canopy will form at a height convenient for harvesting and other operations. It is desirable to limit the height of the tree at that level by periodical removal of chupon growth. A second jorquette may be allowed to develop if the first one formee was very close to the ground. Generally 3-5 fan branches are developed at each jorquette. When more fan branches developed at each jorquette. When more fan branches develop. one or two weaker ones may be removed. The branches badly affected by pests and diseases also should be removed.
Cocoa Pests and Disease Management-
More than 50 insects have already bean recorded in on cocoa from India.The more important among them have been described here.
Mealy bugs(Planococcus lilacinus Ckll. and citri Risso):
Most important insect pest of cocoa in India is mealy bugs.The adult females and young ones feed on the tender shoots, cushions, flowers, cherelles and pods by sucking up the sap. They also attract various ants. Seedlings and young plants affected by the mealy bugs show retarded growth and excessive branching at undesired height. They also cause cushion abortion and wilting of cherelles.The population of the bugs is more during the summer months. Spot application of anyone of the insecticides viz.. fenthion (Libaycid) 50 ml in 100 liters of water monocrotophos (Nuvacron) 125 ml in 100 liters of water or dimethoate (Rogor) 160 ml in 100 liters of water will maintain the population at a low level. If recurrence of the pest is noticed a second round of spraying is recommended after 30 days.
Tea mosquitoes (Helopeltis antonil) :
These mosquitoes usually damage the pods. Infested pods develop circular water-soaked spots around the feeding punctures. These punctures subsequently turn pitch black in color. Deformation of pods occurs because of multiple feeding injuries. The spraying of Endosulfan (0 .05%) is recommended for control of Tea mosquitoes attack.
Stem borer (Zeuzera coffeae Nietn .):
The red borer of coffee bore into the branches and trunks of cocoa trees. The portion of the branch above the point of entry of the pest dries up. Control of the pest is best achieved by pruning off and destroying the attacked branches and by local application of carbaryl paste.
Aphids (Toxoptera aurantii B de F.):
They colonize on the underside of tender leaves, succulent stem, flower buds and small cherelles. Heavy infestation brings about the premature shedding of flowers and curling of leaves. Spraying with dimethoate (Rogor) at 160 ml in 100 liters of water is suggested.
Stem girdler (Glenea sp):
The larvae of this beetle tunnel the bark first and penetrate deeper making galleries. On younger trees, the pest attack occurs at the jorquette, which normally results in the drying or breaking of the portion above. Mechanical extraction of the larvae and tropical treatment with carbaryl paste are suggested as control measures.
Leaf eating caterpillars :
They include bagworms, caterpillars of Lympantria species and two species of loopers. Several caterpillars and semi loopers feed on the tender foliage, shoots and green bark of cherelles and pods. They may cause serious leaf damage on seedlings and young trees. If the damage is very severe, spraying could be given by mixing 16 ml dimethoate in 10 liters of water.
Leaf eating beetles:
Leaf-eating beetles mainly Mylloceros species and Popillia sp. feed on tender leaves causing a series of irregular holes. They make a sporadic appearance in some areas after rains and cause serious damage. Grubs of these beetles dwell in the soil. Drenching the soil with a suspension of BHC 50% WP at the rate of 20g in 100 liters of water is effective in controlling the pest.
Rats (Rattus rattus) and squirrels(Funambulus tristriatus and F. palmarum) are the major rodent pests of cocoa. They cause serious damage to the pods. The rats usually gnaw the pods near the stalk portion whereas squirrels gnaw the pods in the center. They are known to damage the mature as well as immature cocoa pods whereas the squirrel’s damage only the mature ones. The rats can be controlled by keeping 10g bromadiolone (0.005%) wax cakes on the branches of cocoa trees twice at an interval of 10-12 days.Squirrels are best controlled by trapping with wooden or wire mesh single catch ‘live’ trap with ripe coconut kernel as the bait. The success is more if trapping is carried out during the lean periods of the crop (September-November) and when the alternate foods such as paddy, cashew apples, and jackfruit are not available. Timely harvest of the pods will help in increasing the efficiency of poison baiting as well as trapping.
Black pod disease (Phylophthora palmivora):
It occurs in all the cocoa growing areas in South India during the South-west monsoon period with the maximum incidence in July-August. The infection occurs anywhere on the pod surface. Pods of all ages are susceptible. Pods damaged by rodents/insects or injured while harvesting, pruning or carrying out other cultural operations, are more prone to infection by the pathogen.Infection appears as chocolate brown spot, which spreads rapidly and soon occupies the entire surface of the pod. As the disease advances, a whitish growth of fungus consisting of fungal sporangia is produced over the affected pod surface. Ultimately, the affected pods turn brown to black. The internal tissues, as well as the beans, become discolored as a result of infection. The beans in t he infected pods approaching ripeness may escape infection because they are separated from the husk on ripening. The beans in such pods can be saved by timely harvesting.The disease can be prevented by spraying one per cent Bordeaux mixture at the onset of southwest monsoon rains and thereafter at least twice during the monsoon season at monthly intervals. Frequent removal and destruction of all infected pods will help in reducing the disease incidence to some extent. Overcrowding of trees and thick shade should be avoided.
Preparation of 1 % Bordeaux mixture
Dissolve 1 kg copper sulfate crystals in 50 liters of water. In another vessel containing 50 liters of water, prepare milk of lime with 1 kg quick lime. Pour the milk of lime into the copper sulfate solution slowly stirring the mixture all the while. Test the mixture before use for the presence of free copper, which is harmful to the palm by dipping a polished knife in it. If the blade shows a reddish color, add more lime till the blade is not stained when dipped a fresh in the mixture. Always use wooden or earthen or copper vessels for the preparation of Bordeaux mixture.
Preparation of 10% Bordeaux mixture paste
For the preparation of Bordeaux mixture paste, 100 9 copper sulfate and 100 g quick lime each are dissolved in 500 ml of water separately and mixed thoroughly.
Canker (P. palmivora):
The cankers appear either on the main trunk, jorquettes or fan branches. The earliest symptom is the appearance of a grayish brown water-soaked lesion on the outer bark. A reddish brown liquid oozes out from these lesions, which later dries up to form rusty deposits. The tissues beneath the outer lesion show reddish brown discoloration due to rotting. When these cankers girdle the main stem or branches, dieback symptoms appear and ultimately the tree dies. The infection may also spread from the infected pod to the peduncle and then to the cushion and bark.All infected pods should be removed and destroyed. The disease can be controlled in the early stages by removing the infected tissues and applying Bordeaux paste. The good drainage system is to be provided in the garden.
Charcoal pod rot (Botryodlp/odia theobromae) :
This disease, though known to occur throughout the year, becomes severe during summer months. Pods of all ages are susceptible. Infection appears as dark brown to black colored spot. The affected spots turn black and remain on the tree as mummified fruit. The internal tissues are rotten and the affected beans turn black. Spores appear in masses forming a soot. Infection takes place through wounds. Spraying with one percent Bordeaux mixture is recommended to control this disease.
Pink disease (Pellicularia salmonicolor) :
It is characterized by the presence of a pinkish powdery coating on the stem. It causes wilting of shoots, shedding of shoots, shedding of leaves and finally drying up of the branch. The disease persists from season to season through dormant mycelium inside the bark and in the cankerous tissues. It is checked by pruning the affected branches and swabbing the cut ends with Bordeaux paste. The disease can be prevented by regularly spraying with 1% Bordeaux mixture.
The shriveling and mummifying of some young fruits are a familiar sight in all cocoa gardens. In the early stages the fruits lose their luster and in four to seven days the fruits shrivel. The fruits may wilt but do not abscise. Many factors are associated with this malady. The most important factors are: insects, diseases, for nutrients competition, overproduction etc. Hence, the remedial measures will depend upon the nature of the causative factors involved.
White thread blight (Marasmius scandenS):
White thread blight is observed in some of the gardens in Kerala and Karnataka states. The white mycelial threads of the fungus spread longitudinally and irregularly along the surface of the young stem or branches. The growth of the fungus is very rapid under the favorable condition of high humidity, and the infection enters leaf lamina along the petioles. On the leaf lamina, it spreads exclusively. The affected leaves turn dark brown. These dead leaves eventually get detached from the stem but are found suspended by the mycelial thread. The extensive death of the young branches and suspended leaves are the common field symptoms.Thread blight disease can be controlled effectively through removal and burning of the affected parts. Removal of heavy shade will also help in the control of the disease.
Vascular streak die-back (Oncobasidium theobromae):
This disease is mainly found in Papua-New Guinea and Malaysia . It is also reported from some parts of Kerala. The first indication of the disease is a characteristic yellowing of one or two leaves on the second or third flush behind the growing tip. Diseased leaves fall within a few days of turning yellow. The other leaves on the shoot soon show similar symptoms.When the infected shoot is split lengthwise there is always a characteristic brown streaking of the woody tissue extending well beyond the region of yellowed leaves. The disease is spread by spores produced on diseased branches, which are released only at night under certain specific climatic conditions and are dispersed by the wind. A spore, which is deposited on a young flush can initiate a new infection. The disease can be controlled by the disposal of diseased branches and regular pruning of chupons on the trunk. Cocoa nurseries should not be located near the diseased trees.
Zinc deficiency is observed in many cocoa gardens in Kerala, Tamil Nadu, Andhra Pradesh and Karnataka states. The initial symptom is chlorosis of the leaves. This appear in patches and in advanced stages the green areas are found only along the vein margins, giving a vein-banding appearance to the leaves. Affected leaves show mottling and crinkling with wavy margin. Most of the younger leaves become narrow and sickle-shaped showing characteristic ‘little leaf’ symptom. Symptoms on twigs Include rosette and dieback. Shortening of internodes causes a rosette type of growth. In severe cases, premature defoliation followed by dieback of the branches occurs. Zinc deficiency can be corrected by foliar spray of a mixture of 0.3% zinc sulphate and 0.15% (w/v) lime.
Harvesting and processing of cocoa-
Cocoa produces flowers from the second year of planting onwards, and the pods take about 140-160 days to ripen. Each pod will have 25-45 beans embedded in a white pulp (mucilage). Cocoa gives two main crops in a year, i.e. , September-January and April -June though off-season crops may be seen throughout the year especially under irrigated condition.
Ripe pods are to be harvested without damaging the flower cushions by cutting the stalk with the help of knife. The harvesting is to be done at regular intervals of 10-15 days. The damaged and infected pods are to be separated to ensure better quality of beans after processing. The harvested pods should be kept for a minimum period of two days before opening for fermentation ; however, the pods should not be kept beyond four days. For breaking the pods, wooden billet may be used. After breaking the pods crosswise, the placenta should be removed together with husk and the beans are collected for fermentation.
- Central Plantation Crops Research Institute, Kasargod,Kerela.