COCOA (Theobroma cacao, Linn.)Outlines:

The cocoa plant and its distribution

Cultivated species of cocoa

Botany and Agronomy of cacao

Insect and disease pests of cocoa

Harvesting and post-harvest handling of cocoa.

Cocoa Plant And Its DistributionCocoa has currently been reclassified as a member of Malvaceae instead of Sterculiaceae families.

The crop originated from the foot of the Andes in the Upper reaches of Amazon river.

Theobroma contains about 22 species, all locally used for refreshing beverages, cooked dishes and jellies.

Brief History Of Cocoa CultivationEvidently, the Maya Indians firstly cultivated cocoa in Mesoamerica over 2000 years ago, the beans being consumed and as currency.

The Aztec Indians collected high levies / taxes in form of cocoa beans cacahoatl the name cocoa.

The tribes attributed divine origin to cacao through a god Quetzacoatl (the plumed serpent).

Its beverage is referred to as xocolatl hence the name chocolate.

The sacredness of the crop made Linnaeus to name cultivated cocoa as Theobroma cacao food of gods

Cocoa plantations were first established at Martinique in 1660 and Brazil in 1754.

Introductions Of Cocoa PlantationsThe Spaniards, Dutch, and Portuguese introduced cocoa to their overseas territories.

By 1874, cocoa got to Nigeria and Ghana from Fernando Po (now Malabo).

By 1887, cocoa established in Ibadan - seedlings from Botanical Garden, Ebute-Meta Lagos.

Cocoa got to West African peasant farmers through:Trading companiesMissionariesSoldiersChiefsFarmers associationsCooperativesDepartments of AgricultureWest African Cocoa Research Institute (WACRI) (defunct)Cocoa Research Institute of Ghana (CRIG)Cocoa Research Institute of Nigeria (CRIN)

Cultivated Species Of CocoaThe Criollo, The Amazonian forastero and The Trinitario

The Criollo group:Cultivated in Venezuela, Nicaragua, Mexico, Colombia and Guatemala.Most anciently cultivated.Poor cacao vigour.High susceptibity to diseases.Slender cacao with green pods.Watty, thin and soft pericarp.Lignified mesocarp.Plump beans, embedded in pulpy mucilage with white cotyledons.Fermented and dried cotyledons are light brown.Excellent bean flavour.

The Amazonian Forastero GroupCultivated in Brazil, West Africa, Central America, South East Asia and Caribbean Island.

Staminodes with purple pigments.

Green and varying shapes of cocoa pods.

Thick pericarp and very woody mesocarp.

More or less flat beans

Dark purple cotyledons

Relatively bitter flavour and acid taste.

West African Amelonado belongs to this group.

The Trinitario GroupBelieved to evolve from a cross between Forastero and Criollo groups.

Highly heterogeneous group.

Selected from Trinidad, hence the name Trinitario.

Cultivated in Mexico, Central America, Trinidad, Colombia, Venezuela and some African and South East Asian countries.

Botanical traits are intermediate between Forastero and criollo groups.

Bean flavour is also intermediate between Forastero and Criollo groups.

Botany And Agronomy of CocoaCocoa is cauliflorous and semi-desidous.

Height, leaf area, branches and canopy spread of cacao determined by planting spacing.

When grown from seeds cacao attains anthesis between 24 and 36 MAT and fully matured at about 10 YAT.

A well managed cocoa continue to be economic for over 50 years.

Dimorphous root: Orthotropic taproot and Plagiotropic lateral root.

3 to 4 DAS cocoa seeds start germinating through the emergence of whitish taproot and lateral roots.

10 YAT, taproot well developed, (1.5m) with a mass of root hairs covering 5 6 m around cacao.

Botany and Agronomy of Cocoa Contd.Stem growth is orthotropic holding the leaves.

The orthotropic growth is intermittently interrupted by the degeneration of the terminal bud, below which branches develop Jorquette.

Thus, there can be 1st and 2nd jorquette which form the framework of cacao.

pruning starts at the level of 2nd jorquette through the removal of excessive orthotropic shoots chupons.

Growth in cacao is discontinuous and in successive growth phases flushes.

Each flush results in the production of 5 6 alternate leaves with short petioles and 4 5 flushes occur in a year.

The young pigmented leaves may be pale-green, pink or deep blue depending on variety, mature leaves are dark-green with 7 9cm petiole length.

Flowering is marked indicator of successful field establishment, and anthesis may be attained in 2 years in improved varieties and it may take a longer period in unimproved varieties of cocoa.

Botany and Agronomy of Cocoa Contd.Flowering depends on favourable physiological, soil and climatic conditions.

In mature cocoa, fruiting occurs twice a year in the tropics dry (November / December) and rainy (June / July) seasons.

Cocoa is an out-breeder and an entomophilous plant. Pollinators midges, ants, thrips and leaf hoppers.

Within 36 hours after pollination, fertilization occurs leading to the formation of a young okra-sized pod cherelle.

Cherelle continues to develop by longitudinal elongation and girth increase to become a fully-grown mature cocoa pod.

It takes up to 150 180 days between fertilization and pod maturation. Ripe pods are light-yellow in colour and thus ready for harvesting.

A cocoa pod contains 30 40 beans on the average and 50 60 pods needed to plant an hectare of cocoa spaced 3m x 3m.

Figure 1: Developing cocoa pods (A Cherelle and a pod).

Site Selection2 major factors must be considered while selecting a site for cocoa plantations establishment: climatic and soil factors.

Climatic factors:

Cocoa is a low altitude crop, performing best within 100 300m above sea level (asl). It can be grown at 700m asl.

Cocoa is sensitive to water deficiency particularly when in competition with other plants (shade plants, wind breaks and weeds) and also to excess water in the soil.

It thrives within wide rainfall ranges of 1000 3000mm or more per year.

The site should enjoy an evenly distributed rainfall of 150mm/month and at least for 9 months.

With provision of irrigation and limited occurrence of dry winds, cocoa can be cultivated completely without rain.

Cocoa responds to temperature variations: the maximum being 30 -320C while the minimum is 18 210C. At a temperature lower than 100C, cacao becomes damaged.

Climatic factors contd.Cocoa enjoys high relative humidity of between of between 70 80%, above which disease infection occurs and below which (obtainable in the dry season) cocoa leaves become limp and droop, thus causing severe defoliation.

The deleterious effects of drying and strong winds like harmattan (in West Africa) is reduced through wind breaks, shade trees or even by high density planting. This is because cacao rooting is superficial thus offering little resistance to strong and drying winds.

At early stage of cocoa plantation establishment, temporary shading is indispensable. A temporary shading / a nurse plant should meet the following conditions :

Easy establishmentProvision of good overhead shade throughout the dry seasonLittle competition wit young cocoa transplants for moisture and nutrientsShould not serve as alternative host to cocoa disease and insect pestsEasy removal when no longer neededIts removal should not pose any threat to the plantation.

Soil FactorsThe soil on which cocoa will be planted should satisfy the following conditions:The soil must be at least 1.5 m deep.

The soil structure must be as homogenous as possible.

It must have good water-retaining capacity, well-drained and well aerated.

Sandy soil is not suitable except it contains high organic matter and not under prolonged hot and dry season.

It must be of acceptable chemical properties.

It must have pH of between 5 and 8 optimum being 6.5.

High organic matter content in the topsoil is essential for good growth and high productivity.

Raising cocoa seedlings in the nursery.Cocoa beans readily germinate when sown and lose viability easily on extraction from pods within 5 t days unless specially treated with moist fine sand or sawdust. They retain viability for 4 weeks inside pod after harvesting.

Nursery establishment is done between December and February, in order to allow the seedlings a period of 4 months under intensive care.

Seedlings bags of 20/25cm x 12cm are used for raising the seedlings. The are filled with sifted top soil, heavily watered the previous day and arranged under a shade in the nursery.

The beans are sown at seeding rate of 2 per bag and later thinned to 1 per bag after germination. Daily light watering till germination at 7 -10 days. Adequate watering follows.

Regularly examine for the incidence of disease and insect pests. Seedlings that show symptoms of bacterial or viral infections must be burnt outside the plot. Fungal and insect attacks are chemically controlled.

Transplanting Of Cocoa Seedlings Into The Field.In preparing the land for cocoa transplanting, some trees are left unfelled to act as windbreaks (upper storey).

The field should have been planted to a temporary shade of plantain suckers the previous year or simultaneously with cocoa seedlings (middle storey) at same planting density with cocoa (100% shade density).

Both upper and middle storey are to provide conducive environments for cocoa transplants when eventually transplanted.

Prior to transplanting, the seedlings should undergo hardening gradual exposure of the seedlings to environmental conditions obtainable on the field, especially, light.

Transplanting of cocoa seedlings is carried out when the rains are steady.

Transplanting contd.Vigorous seedlings are transplanted with ball-of-earth at the age of 4 5 months. Bare-rooted seedlings are treated with clay slurry or artificial polymer before transplanting.

Transplanting of overgrown seedlings, seedlings in flush or seedlings with broken taproot results in high seedlings mortality / low survival percentage after transplanting.

Alternatively, cocoa can be transplanted into a selectively thinned forest or along traces cut through regrown forests.

The crop is transplanted at a spacing of 3 m x 3 m giving a plating density of 1,111 plants/ha. High density planting in cocoa is practicable.

Vegetative / Clonal Propagation in CocoaConventionally, cocoa is clonally propagated through budding, grafting, cutting, marcutting (air layering) and soil layering. Cutting being the most popular method.In rooting stem cuttings, the following precautions should be adhered to:Fan branches should be taken for rootingCuttings should be taken in the early hours of the day and setting done same day.The stem base of the cutting should not be thicker than the stem of a lead pencil.Set cuttings in an humidified chamber made of transparent polythene sheet.A fine jet sprayer should be used for watering to saturate the air inside the chamber.After successful rooting (ramets) cuttings should be hardened off and subsequently kept in the nursery till transplanting.The shade provided should be uniformIf sawdust should be used, it should have been partially weathered 3 months in the dumping site.The hardened off ramets are transplanted into the field under a combined temporary and permanent shading.

Cocoa Disease PestBlack pod / Phytophtora pod rot: Most serious disease of cocoa in West Africa, especially, Nigeria and Cameroon.

Caused by Phytophtora megakarya, during the rainy season when the relative humidity is higher than 80%.The causative organism had hitherto been P. palmivora, but the strains had been brought to a low level.

Damage characteristics include:rotting of pods which begins with small brown spot with irregular water soaked margins. Tiny whitish downy mould, at the centre of the brown spotEnlargement of brown spot and downy mould until the entire pod is covered The beans contained become rotted. This may take up to 18 days in matured and normal-sized pods.

Phytophtora pod-rot is different from cherelle wilt, which is a physiological disorder.

Under severe attacks, especially when there is long periods of rains cool weather, chupons, seedlings and leaves are attacked and killed.

The spread is through and infected pod by rain drops.

Figure 2: A cocoa pod infected by P. megakarya.

Control of Phytophtora pod rotThe incidence of the disease is preferably prevented in the cocoa plantation through:

Frequent removal of weeds / other plants that can increase the relative humidity of the plantation.

Removal and burning of the infected cocoa pods.

Application of the copper-based fungicides to control the incidence.

The use of resistant / tolerant varieties.

Swollen shootA viral disease which may not appear till 6 months after cacao is infected.

Symptom appears at the shoots produced after infection.

Characteristics of infection:A network of red vein bandingVein clearingChlorosisSwellings of the stems, fan branches, chupons and seedlingsInfected pods become rounded and small with some mottling.Infected cocoa seedlings have reduced plant height, stem diameter, number of leaves, number of roots and root length.The disease does not affect stem / root ratio.

Control measures:Removal and burning of the infected cacaoBreeding programme has put the disease under check through the introduction of the resistant / varieties.

Cherelle wilt

Major insect pests of cocoaCocoa Mirids (Capsids or Jori-jori): Most serious insect pest of cocoa in West Africa.The insects attack both young and mature cacao.Cocoa mirids are of 3 types:

(1) Sahlbergella singularis (Brown mirids): Feed on pods, chupons, soft and hard wood branches and tips.

(2) Distantiella theobromae (Brown mirids): Feed on pods, chupons and fresh green shoots especially, on young plants. Mainly found in Ife-Ondo-Akure area of Nigeria.

(3) Helopeltis bergrothi (Cacao mosquito): Feed on pods.

Mirids feed at night and rest during the day at the axils of leaves and behind the pods.Mirids are vectors of weak fungal pathogens especially die-back infections.

Mealy bugsMealy bugs are vectors of viral disease especially swollen shoot.Control methods:

Chemical control method is effective, but the hard cuticle of the insect prevents penetration of the insecticide.

Use of systemic insecticide through cacao results in toxicity of cocoa.

Chemically killing the ants that provide shelter for mealy bugs is found effective.

Exposure of mealy bugs following killing of the ants results in the reduction in numbers of the mealy bugs.

Biological control method through the use of mealy bug predators has not been effective.

Spraying of a fungus (Cephalosporium sp.) cultured in rice and crushed in water is very effective against these mealy bugs.

Harvesting and post-harvest handling of cocoaIt takes 150 180 days between pollination and ripening in cocoa, depending on varieties.

Only mature and ripe pods are harvested, diseased and damaged pods must not be processed for markets.

Harvesting should be regular and frequent in order to avoid damage due to over-ripening, disease and animals.

In a case of irregular / delayed harvesting, the beans start germinating in-situ, such cocoa is unsuitable for marketing.

Harvesting of unripe cocoa pods results in poor-quality beans with low aromatic compounds after fermentation.

During harvesting flower cushion must not be damaged, if damaged, subsequent years harvests will be reduced.

Cocoa pods must not be pulled off in order to avoid any damage to flower cushions.

Pods are ready for harvesting when colour changes from green to yellow/pink/red, depending on varieties.

Harvesting contd.In West Africa, there 2 cocoa seasons:Main crop season September to MarchLight crop season April to August

Harvesting tools include:Sharp cutlass, for removing pods within easy reach.A sharp knife with short handle, for removing pods well above ground level.A sharp knife attached to a long pole (go-to-hell) for plucking pods at the top-most part of cacao.A basket or other container for packing pods.

Breaking / opening of cocoa pods:

Never use a cutlass. Use a blunt object such as a stone or a thick piece of wood for the breaking. This is to avoid damage to cocoa beans.

Extracted beans with mucilaginous pulp are collected in a clean container for fermentation.

Preparation of Commercial CocoaIn order to be sold as cocoa beans, the fresh cocoa removed from pods have to undergo two very important processes Fermentation and Drying: The main aim of which include:

To remove the mucilaginous pulp which surrounds the beans.

To cause the death of the embryo and consequently prevents it from germinating.

To bring about complicated biochemical changes inside the cotyledons, leading to a reduction in the bitterness and astringency thus enabling the precursors of the chocolate flavour to develop.

Finally, to reduce the water content of the fermented beans from approximately 60% to 6 7%, in order to block the enzymatic reactions and to enable the commercial product to be stored safely, free from pests and diseases.

FermentationFermentation in cocoa is a process by which mucilaginous pulp surrounding the beans is removed under the gradual influence of heat and pressure for the purpose of removing the beans bitter taste and the development of acceptable bean flavour and colour.

It is necessary to ferment cocoa beans in order to fulfill the following conditions:

To get the proper taste, colour and flavour associated with cocoa products.

To kill the embryo and stop germination.

To remove pulp/mucilage so that the beans may dry properly.

To loosen the skin from the cotyledon thereby allowing easy and proper de-shelling during processing.

Cocoa is fermented by different methods of fermentation which include:Heap fermentationBasket fermentationSweat box fermentationTray fermentation.

Heap Fermentation Wooden base with perforated banana/plantain leaves.

Fresh cocoa beans are piled on the platform until a heap of 60 90 cm high is made.

The heap is covered with the leaves again and weigh down with logs of wood in order to retain the heat.

The heap is thoroughly turned on the 3rd and 5th days with a wooden spade or hand.

The mixing should be fast in order to avoid heat losses.

The cocoa beans are fully fermented and ready for drying on the 7th day.

Basket Fermentation Woven baskets lined with perforated banana / plantain leaves to facilitate drainage of the sweating.

The baskets are placed on a wooden raised platform to aid further drainage.

After being filled with cocoa beans, the baskets are tightly covered with banana / plantain leaves again and pressed with stones / wooden logs.

Turning into another basket is done on the 3rd and 5th days.

On the 7th day, fermentation completes.

Sweat Box Fermentation An improved method employed in large cocoa plantations.

Three wooden boxes (90 x 90 x 90 cm each / 120 x 120 x 120 cm) each, perforated at the bottom are used.

One side of the box should be removable and no lid is necessary.

The boxes are placed on raised platforms for aeration and drainage.

This method requires a ventilated and roofed building with adequate drainage system against rains.

The boxes are arranged in steps on top of one another.

The fresh beans are placed on the top-most box, covered with sufficient banana/plantain leaves and sacks and pressed with stones / wood.

The beans from the top-most box are turned into the middle and last boxes on the 3rd and 5th days respectively and covered as before.

On the 7th day the beans are properly fermented and ready for drying.

Tray Fermentation An efficient and standard method of fermentation in a number of cocoa countries.

The bottom of the tray is covered with slatted mat made from palm frond midribs.

The 4 sides of the tray (75 x 75 x 10 cm) are made of strong wood.

The trays are filled with the wet beans to a desired level.

The first tray is placed on a raised wooden platform to facilitate aeration and drainage.

The number of the trays used depends on the volume of the cocoa beans, but 10 or more trays could be stacked upon one another to a convenient height for handling.

The wet beans, when loaded into the trays are covered with banana / plantain leaves and sacks to retain the heat.

The beans are properly fermented on the 4th day of fermentation and are ready for drying.

The advantages of this method are as follows: It requires far less labour compared to other methods.The average cost of a tray is not much and a try can be used for more than 2 years.It is fast, only 4 days required to complete fermentation.No mixing of beans required and good and well-fermented cocoa are obtained.

Factors Affecting Fermentation of Commercial Cocoa.The degree of ripeness of cocoa pods. Healthiness of cocoa pods.Types of cocoa: Criollos ferment at a shorter periods compared to Forasteros and Trinitarios.Climatic and seasonal variations: Low temperature of high altitude (800 m asl) slows the rate of fermentation. The weight of pulp and sugars per bean depend on growing conditions. Bean has limited amount of pulp during the dry season.Quantity of cocoa: A minimum quantity of about 70 90 kg of fresh bean is needed per fermentation unit in order to have a satisfactory fermentation.Duration of fermentation: A complete fermentation gives the bean a uniform brown colouration. Inadequately fermented cocoa bean has purple colour and this gives a bitter and astringent product. An excessively long fermented cocoa bean runs the serious risk of having a very bad taste due to the commencement of putrid fermentation.

Drying.

The aim of drying is: to reduce the water content of fermented cocoa beans from about 60 % to 8 %. to ensure that cocoa is kept under good conditions for storage and transportation. If drying is slow, mould may develop.If drying is too rapid, oxidation may be prevented, acetic acid may be retained in the cotyledon resulting in excessive acidity of the cocoa beans. Flat beans, germinated beans and broken beans as well as foreign bodies must be removed.

Methods of drying.Sun-dryingDrying autobus Movable roof dryer.Simple dryersMechanical dryersAutomated workshops.

Test for dryness.A well-dried cocoa bean will crack when squeezed between the fingers.Cut through the sample beans with a knife, if properly dried, the cotyledon will separate easily.

Grading of cocoa.Grade 1 cocoa: less than 3 % slaty, mouldy and defective beans each.Grade 2 cocoa: less than 5 %, 4 % and 5 % slaty, mouldy and defective beans respectively.The international standards state that the net weight of a cocoa bag must be 62.5 kg, (16 bags makes a ton).Cleaning and bagging of cocoa.Sorting and elimination of flat, broken, germinated beans and other impurities.The beans are packed in jute bags. Polythene bags must not be used for bagging cocoa. Storage of commercial cocoa.The international standards stipulate the following conditions.The ambient humidity must not exceed 70 %.The bags must be stored at least 7 cm above the ground in order to allow air circulation.There must be at least a passage of 60 cm between the walls and the bags and between bags of different types of cocoa.Disinfect by fumigation. Protection against rodents and other pests must be carried out as and when due.Steps must be taken to avoid contamination by odour, off-flavours or dust. Periodic checking of the moisture content of each lots must be carried out.

Economic Importance Of Cocoa.Beverages (not tea)Foreign exchange earnings.Black soapsHerbsChocolatesIce creamCocoa juiceWine productionJin productionHair creamBody creamToilet soapsFire woodOrganic nutrient sourcesWrapping of pap Employment generationRecreational / ornamental usesIncome generation.

Figure 1: Developing cocoa pods (A Cherelle and a pod).*

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