Cocoa wood \u0026 lass

$: Cocoa wood \u0026 lass$
Cocoa

Fourth Edition

G. A. R. Wood, BA, DTA formerly Cadbury Schweppes plc

arid

R. A. Lass, B.Sc. (Agric.), DTA Cadbriry Schweppes plc

b Blackwell Science

Cocoa

TROPICAL AGRICULTURE SERIES

The Tropical Agriculture Series, of which this volume forms part, is published under the editorship of Gordon Wrigley

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Cocoa G. A. R. Wood and R. A . Lass Coffee G . Wrigley

Payne

Wilson

G. Williamson and W . J . A . Payne

Cocoa

Fourth Edition

G. A. R. Wood, BA, DTA formerly Cadbury Schweppes plc

arid

R. A. Lass, B.Sc. (Agric.), DTA Cadbriry Schweppes plc

b Blackwell Science

(For Blackwell Science Books - + IOWA address in left column & as dibtrihutor. 07/03/01) (iv)

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British Library Cataloguing in Publication data

Wood. G.A.R. Cocoa.4th ed. - (Tropical agriculture series) I . Cacao 2. Cocoa 1. Title I I . Las. R.A. 111. Series 633.7'4 SB267

ISBN 0-632-06398-X

Library of Congresh Cataloging-in-Publication Data

Wood. G . A. R. (George Alan Roskruge). 1920- Cocoa.

(Tropical agriculture series) Bibliography: p. Includes index. I. Cacao. 2. Cocoa. 1. Lass, R. A,. 1943-

11. Title. 111. Series. SB267.W66 1985 633.7'4 84.17152 ISBN 0-470-20618-7 (Wiley. USA only)

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Contents

PREFACE

ACKNOWLEDGEMENTS

NOTE ON TERMINOLOGY

LIST OF PLATES

LIST OF FIGURES

LIST OF MAPS

GLOSSARY

1

2

3

4

5

6

7

8

9

10

11

History and development G. A . R. Wood

Botany, types and populations H. Toxopeus

Environment G. A . R. Wood

Planting material H. Toxopeus

Propagation G. A . R. Wood

Establishment G. A . R. Wood

Shade and nutrition M . Wessel

Maintenance and improvement of mature cocoa farms R. A . Lass

Replanting and rehabilitation of old cocoa farms R. A . Lass

Labour usage R. A . Lass

Diseases R. A . Lass

vii

ix

X

xi

xv

xviii

xix

1

11

38

80

93

119

166

195

210

234

265

vi Contents

12 Insects and cocoa P. F. Entwistle

13 From harvest to store G. A . R. Wood

14 Quality and inspection G. A. R. Wood

15 Marketing A. P. Williamson

16 Production G. A . R. Wood

17 Consumption and manufacture G. A . R. Wood

APPENDIX 1 Visual symptoms of mineral malnutrition

APPENDIX 2 International Cocoa Standards

APPENDIX 3 Conversion factors

APPENDIX 4 Publications on cocoa

INDEX

366

444

505

528

543

587

598

60 1

607

608

610

Preface to the fourth edition

The text of the third edition was completed in 1973 just before the sharp rise in cocoa prices which stimulated a surge of interest in planting cocoa, particularly in Brazil and Malaysia. This fresh interest gave rise to much new cultural information and to some new problems which led to research projects designed to overcome them. Cocoa production has not greatly increased since 1973, but there have been considerable changes in the distribution of production; Ghana and Nigeria declining in importance, while Brazil, Ivory Coast and South- East Asia have risen. These changes and the new knowledge about cocoa production are dealt with in this new edition which has been almost entirely rewritten and all aspects are dealt with in greater detail and from a wider range of publications than before.

This could not have been done competently and expeditiously without the help of our collaborators. P. F. Entwistle, the author of Pests of Cocoa, has rewritten and enlarged the chapter on ‘Insects and cocoa’; H. Toxopeus, a plant breeder with wide experience of cocoa, has contributed the chapters on botany and planting material, while his fellow-countryman, M. Wessel, has written the chapter on shade and nutrition. The institutions to which these three currently belong are given in the chapter heads. A. P. Williamson, the director in charge of cocoa buying for Cadbury Schweppes plc, has brought the chapter on cocoa marketing up to date. We are most grateful to all these contributors.

We would also like to thank many others for their advice and assistance to us and to our collaborators during the preparation of this book: C. A. Thorold for his interest in the history of cocoa; A. J. Smyth ana E. A. Wyrley-Birch of the Land Resources Division of the Overseas Development Administration; W. E. Freeman of Trinidad; P. de T. Alvim of CEPLAC, Brazil; H. C. Evans of the Common- wealth Mycological Institute; A. J. Bailey of the Royal Botanic Gardens, Kew; J. D . Mumford and B. E . J. Wheeler of Imperial College; P. H. Gregory, formerly of Rothamsted Experiment Station; Salman Shah of Borneo Abaca Ltd, Sabah; C. Prior of Lowlands

... VIII Preface

Experiment Station, Keravat, Papua New Guinea; W. Hadfield, J . S. Lawrence, A. C. Maddison and J . Orchard, ODA; M. G. Graham, Agrotech Associates, Sabah.

Many of our colleagues at Cadbury Schweppes, Bournville, have assisted us, including A. J . Beales, A. B. Cook, R. J . E. Duncan, P. M. Grist, G . D. Pearse, B. A. Penney, B. D . Powell, P. Smith, P. H. Wiggall, F. J . Stanley and his library staff, Mrs E. Wilkins and the Word Processing Department. Finally, we wish to thank Cadbury Schweppes plc for enabling us to carry out this work and our families for tolerating the inconvenience.

March 1984 G . A. R. Wood R. A. Lass

The occasion of a reprint has been taken to correct some errors and misprints and also to update the figures of production and consumption in chapters 16 and 17.

November 1986 G. A. R. Wood R. A. Lass

Acknowledgements

We are grateful to the following for permission to reproduce copyright material: Agraria Press Ltd for fig 6.3 (Nelliat et a1 1974); British Ecological Society for fig 7.1 (Murray 1975); ’the author, Dr. J . G. Carr for fig 13.3 (Carr et a1 1979); CommissCo Executiva do Plano da Lavoura Cacaueira for Table 3.7 (CEPECkEPLAC, 1974); The Cocoa Chocolate & Confectionery Alliance for figs 13.4, 13.7 (Anon 1983), Table 13.3 (Dougan 1980); the Editor, Cocoa Growers’ Bulletin pub. Cadbury Schweppes plc for fig 5.1 (Edwards 1959), Tables 3.2 (Lee 1974), 3.4 (Smyth 1980), 5.2 (Shepherd 1976), 7.5-6, 7.9, 7.14 (Wessel 1980); Cocoa Producers’ Alliance for Table 6.9 (Bonaparte 1981b) 0 Cocoa Producers’ Alliance; Department of Agriculture, Sabah for fig 6.1 (Wyrley - Birch 1978); the Controller of Her Majesty’s Stationery Office for Tables 17.3-4 (Paul & Southgate 1978); the Editor, The Journal of Horticultural Science for fig 7.2 (Ahenkorah et a1 1974); The Incorporated Society of Planters for fig 6.2 (Mainstone 1972), Tables 7.3 (Thong & Ng 1978) 7.12 (Ebon et a1 1978); Inter-American Institute for Cooperation on Agriculture for Table 13.1 from page 350 (Hardy, 1960); International Board for Plant Genetic Resources for fig 219 (Anon 1981); Koninklijk Instituut Voor De Tropen (Royal Tropical Inst.) for figs 7.3-4, Tables 7.7, 7.10-11, 7.13, 7.15 (Wessel 1971); Longman Group Ltd for figs 12.1-12.23 (Entwistle 1972); Macmillan Accounts & Administration Ltd for fig 2.7 from fig 18 (Van Hall 1932); Smithsonian Institution Press for figs 2.1-2.3a/b, 2.6, 2.8 (Cuatrecasas 1964).

We have unfortunately been unable to trace the copyright holders of figs 2.4a,b,c (Van Himme 1959) and Table 16.3 (Ankrah 1974) and would appreciate any information which would enable us to do so.

Note on terminology

In this edition we have standardised on the names of certain diseases: 1. ‘Phytophthora pod rot’ is used in place of ‘black pod’ in order to

avoid confusion in other languages. 2. ‘Monilia pod rot’ is here called ‘Moniliophthora pod rot’ owing to

the proposed change in generic name, though the former name is still in widespread usage.

I t should also be noted that BHC is referred to as HCH in line with modern nomenclature.

As the book was going to press it was learnt that the generic name of the cocoa pod borer Acrocercops cramerella has been changed to Conopomorpha (Bradley 1985). The earlier familiar name appears in the text.

Ref. Bradley, J. D. (1985) A change of generic name for the cocoa moth Acrocercops cramerella (Snellen) (Lepidoptera: Gracillariidae) Entomologists’ Record 97: 29-30.

Colour between pages 172-173 and 268-269

I.

11. 111. IV . V.

VI.

VII. VIII.

IX . X.

XI. XI1 .

Botanical illustration from Der Cacao und'die Cho- colade by Alfred Mitscherlich, Berlin 18.59. Symptoms of nitrogen deficiency. Symptoms of iron deficiency. Symptoms of potassium deficiency. Symptoms of calcium deficiency. Cocoa beans showing defects and degree of fermentation. Phytophthora canker, West Africa. Vascular-streak dieback, Papua New Guinea. Pods attacked by Phytophthora spp. Nigeria. Attack by Crinipellis perniciosu on pods. Pod attacked by Moniliophthora pod rot, Ecuador. Pod rot caused by Truchysphaera fructigena, Ghana.

Black and white

P1. 2.1

P1. 2.2 P1. 2.3

P1. 2.4

P1. 2.5 P1. 4.1 P1. 5.1

Amelonado cocoa pods showing arrangement of beans. Young cocoa plant showing jorquette. Young cocoa tree with jorquette and five fan branches, bearing cherelles and pods. A seven-year-old cocoa tree grown from a fan cutting . A cocoa farm in West Africa. Comum cocoa pod from Bahia, Brazil. Plastic tube covering a flower bud for hand- pollination.

13 14

1.5

15 25 8.5

97

xii Plates

PI. 5.2 A cocoa nursery in West Africa. P1. 5.3 A cocoa nursery in Malaysia under rubber trees. PI. 5.4 A cocoa nursery in Sabah, Malaysia. PI. 5.5 P1. 5.6 PI. 5.7 P1. 5.8

PI. 5.9

P1. 5.10 PI. 5.11

PI. 5.12

P1. 5.13

P1. 6.1 PI. 6.2 P1. 6.3

PI. 6.4

PI. 6.5 PI. 6.6 P1. 6.7 PI. 6.8 P1. 6.9 P1. 9.1

P1. 10.1

P1. 11.1

PI. 11.2

PI. 11.3

PI. 11.4 PI. 11.5 P1. 11.6 PI. 11.7

PI. 11.8

A seedling ready for planting. Rooted stem cutting. A simple propagating bin for cuttings, Nigeria. Budstock from fan branch, showing pruned leaf petioles. Seedling stock panel opened to receive budpatch; note short ‘tongue’ of bark at lower end. Budpatch extracted from budstick. Operator holding budpatch by petiole remnant while placing budpatch against stock panel. Seedling stock showing budpatch and tape after tying. An oblique upward cut is made to arch over the stock of a successfully budded plant. Cocoa under forest shade, Ivory Coast. Young cocoa under thinned forest, Cameroon. Cocoa under temporary shade of bananas, Ivory Coast. Young cocoa under Leucaena leucocephala, Papua New Guinea. Cocoa under Gliricidia sepium, Malaysia. Seedling cocoa under coconuts, Malaysia. Young cocoa under coconuts, Malaysia. Young cocoa under arecanuts, India. Mature planting of rooted cuttings, Trinidad. Regrowth of an old cocoa tree from a basal chupon, Cameroon. A small cross-country vehicle in use on an estate in Trinidad. Witches’ broom disease - a typical vegetative broom. Witches’ broom disease - brooms and malformed pods. Young seedling infected with witches’ broom, Ronddnia, Brazil. Cushion gall disease. Warty pod, West Africa. Cocoa swollen shoot virus, leaf symptoms. Vascular-streak dieback. Early and advanced symptoms. White thread-blight. Mistletoe, Ivory Coast. P1. 11.9

PI. 11.10 Mistletoe, Equatorial Guinea.

100 100’ 102 103 106 110

113

113 115

115

115

115 119 121

123

127 129 139 140 143 159

223

254

286

287

288 301 305 313

325 341 348 349

Plates

PI. 12.1 Capsid damage in West Africa. PI. 12.2 Pod damage by Distantiella theobroma West

Africa. P1. 12.3 Pod damaged by Helopeltis spp. PI. 12.4 Mist-blower used for capsid control in Ghana. PI. 12.5 Pod damaged by Bathycoelia thalassina. PI. 12.6 Mealybugs: nymphs of Planococcoides njalensis. P1. 12.7 Pod damaged by Acrocercops cramerella. P1. 12.8 Pupae of A . cramerella on cocoa leaf. PI. 12.9 Pod damaged by Marmara spp. PI. 12.10 Rat damage to pod in Malaysia. P1. 12.11 Squirrel damage to pod in Malaysia. PI. 13.1 Opening pods, Cameroon. PI. 13.2 Mules carrying wet beans, Bahia, Brazil. PI. 13.3 A cascade of boxes, Ivory Coast. P1. 13.4 A row of fermenting boxes, Ecuador. P1. 13.5 A fermenting box showing'slatted floor. P1. 13.6 A cascade of boxes with moveable side wall,

Malaysia. PI. 13.7 The start of a heap ferment, Ghana. PI. 13.8 A heap ferment uncovered. P1. 13.9 Basket fermentation, Ivory Coast. P1. 13.10 Fermenting tray with matting floor. PI. 13.11 Tray fermentation: tiers of trays. PI. 13.12 Pressing wet beans with hydraulic ram, Malaysia. PI. 13.13 Simple screw press, India. PI. 13.14 Drying mats in a Ghana village. PI. 13.15 Drying cocoa beans on a concrete floor, Ivory

Coast. P1. 13.16 A row of barcaqas, Brazil. P1. 13.17 A Samoan dryer. PI. 13.18 Fermenting boxes and circular dryer, Sabah. PI. 13.19 Circular dryer, Indonesia. PI. 13.20 A rotary dryer, Papua New Guinea. PI. 13.21 Sheeting a stack prior to fumigation, Ghana. P1. 13.22 Ventilated container. PI. 14.1 The MAGRA cut test device. PI. 14.2 Carrying out a cut test, Cameroon. P1. 14.3 Sampling cocoa before shipment, Ghana. P1. 15.1 The London Cocoa Terminal Market in session. PI. 16.1 Estufa on a small farm in Bahia, Brazil. P1. 16.2 Irrigated cocoa farm in Huila Province, Col-

ombia. P1. 16.3 Drying cocoa on a farm in the Cibao, Dominican

Republic. PI. 16.4 Unloading a mule, Quevedo, Ecuador.

... xi11

373

373 373 381 384 395 402 403 406 426 426 448 450 464 464 465

466 467 467 468 469 469 474 475 480

48 1 48 1 486 488 489 490 499 501 51 1 516 517 533 547

549

551 553

xiv Hares

P1. 16.5 A Criollo tree in Chiapas State, Mexico. P1. 16.6 Sun-drying platform with sliding roof or ‘boucan’,

Trinidad. PI. 16.7 Fermenting boxes, Venezuela. P1. 16.8 A simple dryer, Cameroon. P1. 16.9 A cocoa farm in Ghana. PI. 16.10 Unshaded hybrid cocoa, Ivory Coast. PI. 16.11 Cocoa drying on mats in Nigeria. PI. 16.12 Young cocoa under Gliricidia, Indonesia. PI. 16.13 Cocoa under coconuts, Malaysia. PI. 16.14 Cocoa drying, Papua New Guinea. PI. 17.1 A 12-pot press made by Carle & Montanari.

555

557 559 562 564 569 570 575 577 579 592

Cover Photograph

The original photograph was taken by R. A. Lass and was of a high yielding Amelonado tree on Finca Bonyoma owned by Casa Mallo S. A., Bioko, Equatorial Guinea.

Fig. 2.1 Pod of Theobroma bicolor. Fig. 2.2 Pod of Theobroma grandiflorum. Fig. 2.3 Stem growth of cocoa tree. Fig. 2.4 Root development. . Fig. 2.5 The ideal cocoa plantation. Fig. 2.6 Floral diagram of Theobroma cacao. Fig. 2.7 A cocoa flower. Fig. 2.8 Examples of pod shapes. Fig. 2.9 Shapes of neck and point of pods. Figs. 3.1-11 Climatic data. Fig. 3.1 Itabuna, Brazil. Fig. 3.2 Ouro Preto, RondBnia, Brazil. Fig. 3.3 Pichilingue, Ecuador. Fig. 3.4 Yaounde, Cameroon. Fig. 3.5 Tafo, Ghana. Fig. 3.6 Gagnoa, Ivory Coast. Fig. 3.7 Ondo, Nigeria. Fig. 3.8 Lower Perak, Malaysia. Fig. 3.9 Tawau, Sabah, Malaysia. Fig. 3.10 Keravat, Papua New Guinea. Fig. 3.11 Makanga, Malawi. Fig. 3.12 Sunshine and radiation data, Pichilingue,

Fig. 3.13 Sunshine and radiation data, Tafo, Ghana. Fig. 5.1 Layout of seed garden in Sabah. Fig. 6.1 Cocoa spacing under permanent and temporary

Fig. 6.2 Planting pattern on a plantation in Malaysia. Fig. 6.3 Change in degree of shade under developing

coconut palms. Fig. 7.1 Effect of fertiliser application on yield of cocoa

grown at different light levels. Fig. 7 .2 Effect of shade removal and fertiliser appli-

cations on yield of Amelonado cocoa in Ghana.

Ecuador.

shade.

12 12 16 17 19 19 20 26 28

40 41 42 43 44 45 46 49 50 51 53

56 57 95

134 135

141

168

169

xvi Figures

Fig. 7.3

Fig. 7.4

Fig. 8.1

Fig. 12.1

Fig. 12.2

Fig. 12.3 Fig. 12.4 Fig. 12.5 Fig. 12.6

Fig. 12.7 Fig. 12.8 Fig. 12.9

The relationships between the phosphate and dry matter content of cocoa leaves on soils with an adequate and inadequate supply of available phosphate. Responses of N and P fertilisers in series I and series I1 trials on farmers' cocoa in Nigeria. Diagrammatic representation of the results of correct and incorrect pruning of cocoa. The world distribution of the genera of bryocor- ine mirids associated with cocoa. (A) Sahlbergella singularis Hagl. (B) Distantiella theobroma (Dist.). Monalonion annulipes Sign. Helopeltis clavifer Walk. Pseudodoniella laensis Miller. Bathycoelia thalassina (H.4) . (A), (B), (C), (D), (E) first; second, third, fourth and fifth instar nymphs. Bathycoelia thalassina (H.-S). Adult male. Amblypelta theobromae Brown. Empoasca devastans Dist .

Fig. 12.10 Tyora tessmanni (Aulm.) Fig. 12.11 Life cycle of Planococcoides njalensis (Laing). Fig. 12.12 Selenothrips rubrocinctus (Giard). Fig. 12.13 Zeuzera coffeae Nietn. Fig. 12.14 Acrocercops cramerella (Snell). Fig. 12.15 Earias biplaga. Fig. 12.16 Leaf damage by workers of Atta cephalotes (L.),

Fig. 12.17 Nest of Atta cephalotes. Fig. 12.18 Adoretus versutus Har. Fig. 12.19 Steirastoma breve (Sulzer). Fig. 12.20 GIenea aluensis'Gah. Fig. 12.2 1 Pantorhytes species. Fig. 12.22 Pantorhytes species. Fig. 12.23 Xylosandrus compactus (Eichh.). Fig. 13.1 Crop pattern at Tafo, Ghana. Fig. 13.2 Crop pattern at BAL, Sabah. Fig. 13.3 Major changes in the pulp during fermentation. Fig. 13.4 Temperature profiles for a box fermentation. Fig. 13.5 Temperature profiles for a heap fermentation. Fig. 13.6 Oxygen profiles for a box fermentation. Fig. 13.7 Oxygen profiles for a heap fermentation. Fig. 13.8 pH changes during fermentation. Fig. 13.9 Changes in acetic acid levels in pulp and

cotyledon of Amazon and Amelonado beans during a heap fermentation.

Brazil.

177

182

202

375 376

377 377 377

386 387 389 389 390 394 399 401 404 40'1

41 1 412 414 416 418 420 420 423 445 446 453 454 455 456 457 458

459

Figures

Fig. 13.10 Changes in lactic acid levels in pulp and cotyledon of Amazon affd Amelonado beans

Fig. 13.11

Fig. 14.1 Fig. 14.2

Fig. 14.3

Fig. 15.1

Fig. 16.1 Fig. 16.2 Fig. 16.3 Fig. 16.4 Fig. 16.5 Fig. 16.6 Fig. 16.7 Fig. 16.8 Fig. 16.9

during a heap fermentation. Monthly variation in recovery and dry bean weight on a farm in Ecuador. Seasonal changes in bean weight in Nigeria. Seasonal changes in quality of beans from one area in India in 1978. Relation of temperature 4 months previously to hardness of cocoa butter. Manufacture of a typical European milk chocolate World production of cocoa 1945/46 to 1980/81. Production graph for Brazil. Production graph for Colombia. Production graph for the Dominican Republic. Production graph for Ecuador. Production graph for Mexico. Production graph for Trinidad and Tobago. Production graph for Venezuela. Production graph for Cameroon.

Fig. 16.10 Production graph for Equatorial Guinea. Fig. 16.11 Production graph for Ghana. Fig. 16.12 Production graph for Ivory Coast. Fig. 16.13 Production graph for Nigeria. Fig. 16.14 Production graph for SCo Tome. Fig. 16.15 Production graph for Malaysia. Fig. 16.16 Production graph for Papua New Guinea. Fig. 17.1 Flow diagram of cocoa and chocolate prod-

uction.

xvii

459

494 522

524

526

541 545 546 550 55 1 552 555 556 558 561 563 565 568 569 572 576 578

59 1

Maps

2.1

11.1

Northern South America showing places and rivers

Map of Northern South America to show known distribution of Crinipellis perniciosa. 284

mentioned in this chapter. 33

16.1 The cocoa-growing areas of West Africa. 573

Glossary

This glossary is confined to some of the less common technical terms used in this book and some words which are peculiar to the cocoa tree.

Allele - one of two alternative genes Cherelle - small and immature pods of the cocoa tree Chupon - vertical stems or shoots of the cocoa tree Clone - group of plants produced vegetatively from one original plant Cultivar - a variety of a plant species Dimorphic - exhibiting two distinct forms Diploid - cell having chromosomes in homologous pairs Drupe - a stone fruit Gamete - mature germ-cell which unites with another in sexual

Heterosis - tendency of cross-bred individual to show qualities

Hypertrophy - abnormal enlargement of organ Hypocotyl - part of embryo or seedling below the cotyledons Isohyet - line joining places of equal rainfall Jorquette - the point at which the vertical chupon stem changes to fan

Necrosis - death of part of leaf or other tissue Orthotropic - vertical growth (chupon) Plagiotropic - oblique growth (fan branches) Saprobic - describes a micro-organism living on decaying organic

Zygote - cell formed by the union of two gametes

reproduction

superior to both parents

growth on the cocoa tree

matter

Chapter 1

History and development G. A. R. Wood

The cocoa tree belongs to the genus Theobroma, a group of small trees which occurs in the wild in the Amazon basin and other tropical areas of South and Central America. There are over twenty species in the genus but the cocoa tree, Theobroma cacao, is the only one cultivated widely.

The headwaters of the Amazon basin have been said to be the origin of the cocoa tree but it is more correct to describe that area as the primary centre of diversity, an area where great variation in morphological and physiological characters is found. The development of the major forms of the species has been explained as follows:

It may be assumed that in early times a natural population of Theobrorna cacao was spread throughout the central part of Amazonia - Guiana, west- ward and northward to the south of Mexico; that these populations developed into two different forms geographically separated by the Panama isthmus; and that these two original forms, when isolated, had sufficiently consistent characters to be recognised as subspecies (Cuatrecasas 1964).

These two subspecies have formed the basis of classification of T. cacao since 1882 when Morris of Jamaica distinguished two great ‘classes’: Criollo and Forastero, and divided the latter into several varieties (Morris 1882).

The varieties that had been cultivated since prehistoric times in Mexico and Central America must have belonged to the Criollo group. The beans tend to be rounded and are white in cross-section, producing cocoa of a weak and special flavour. The trees tend to be susceptible to diseases.

The seeds of Theobroma bicolor, known by the Maya as ‘pataxte’, were also used but were regarded as inferior and were therefore probably collected solely from wild trees and never cultivated.

Cocoa varieties of the Forastero group came into cultivation in historic times. Its trees are hardy and vigorous which is why they now form the greater part of all cocoa grown. Compared to Criollo

2 History and developmeni

the beans are smaller and flatter and the cotyledons are violet. The flavour derived from them is stronger and provides the basis for plain and milk chocolate. The beans have a higher fat content than Criollo beans. Of the Forastero varieties Amelonado has been the one most widely grown. It is relatively uniform and has a smooth yellow pod; it has been the major variety planted in West Africa.

Cultivation in the sixteenth century

When Cortes discovered Mexico City, the capital of the Aztecs, in the sixteenth century he found that cocoa beans were used in the preparation of a drink - ‘chocolatl’ - prepared by roasting the beans, then grinding them and mixing them with maize meal, vanilla and chilli. This mixture was a thick drink stirred with a special whisk. Although the recipe has changed considerably to cocoa beans and sugar, sometimes flavoured with vanilla or cinnamon, a similar thick drink is still made today in Colombia and the Philippines.

Much has been written of the large quantities of chocolatl consumed by Montezuma and his court. It was made from beans sent as tribute to the capital, the crop being grown not by the Aztecs, who lived in an area unsuitable for the cocoa tree but by the Mayas and other subject peoples. While chocolatl was a luxury in Mexico City, it was probably consumed by many classes of people in the growing areas. However cocoa beans had far more sign& cance than as the main ingredient of a drink. Cocoa beans are easy to count and the tributes were paid in ‘cargas’ or loads of 24,000 beans weighing 22.5-27 kg. As the beans were relatively valuable they were used as currency and Oviedo, whose history of the West Indies was published in 1526, stated that in Nicaragua:

everything is bought with cacao, however expensive or cheap, such as gold, slaves, clothing, things to eat and everything else . . . There are public women . . . who yield themselves to whomever they like for ten cacao beans . . . which is their money (Quoted in Bergmann 1969)

The use of cocoa beans as currency appears to have continued for a long time as cocoa beans were being used as small change in Yucatan markets as late as 1840 (Stephens 1843). They were also used in many social and official rituals and various medicinal properties were attributed to cocoa (Thompson 1956). Cocoa held an important place among the Maya as depictions in stone reliefs and figurines from places as far apart as Honduras, Guatemala and Veracruz in Mexico indicate. These go back at least as far as the sixth century. Thus cocoa was a well established crop and article of commerce in the early sixteenth century but we do not know how it reached Central America from its supposed origin in the Amazon

Spread of cultivation 3

basin. The main cocoa areas at the beginning of the sixteenth century were Tabasco, which borders the gulf of Mexico, Soconusco on the Pacific coast of Mexico and also in what is now Guatemala and El Salvador. There is evidence of smaller and scattered areas in Mexico to the north of the major areas and in Nicaragua and Costa Rica. Another significant area was in the Sula valley on the Caribbean coast of Honduras and it was probably a load from this area that was encountered by Columbus in 1502, the first contact of the Old World with cocoa beans (Bergmann 1969).

There is no evidence that cocoa was cultivated in South America or in the Caribbean at that time, although it is thought that cocoa was used for ceremonial purposes in western Venezuela, the beans being collected from wild trees. The type of cocoa grown in Central America must have been what we now call Criollo as there is no indication that Forastero cocoa was cultivated in that region. The reason for this may well lie in the fact that Criollo beans can give a palatable drink with little or no preliminary fermentation whereas Forastero beans require several days’ fermentation.

Spread of cultivation

After the conquest of Mexico cocoa cultivation spread to Caribbean islands and parts of South America, but Mexico remained the major market for cocoa beans until the seventeenth century. Venezuela was one of the first countries where the growing of cocoa was started in the sixteenth century. Some of the earliest plantings were in the valleys along the north coast where, until recently, Criollo cocoa was grown, but there is no record of the origin of the cocoa planted there. Jamaica was another such country and enjoyed a cocoa ‘boom’ around 1670; cocoa was also grown in Trinidad but the exact date of the first introduction is uncertain. A later introduction to Trinidad was made in 1678 from Venezuela with seed of a Criollo type. At about the same time cocoa was introduced to Martinique and Haiti. In Jamaica, Trinidad and Martinique the cocoa crops were devastated by ‘blasts’ at various times. While ‘blast’ has sometimes been assumed to be a hurricane, it is now considered far more likely to have been a disease, possibly Ceratocystis wilt to which Criollo cocoa is very susceptible.

Apart from movement within the Caribbean area Criollo cocoa was taken across the Pacific to the Philippines about the year 1600. From there it spread later to Sulawesi and Java and it is possible that the first introduction of cocoa to Sri Lanka and India came from the East Indies. There is evidence of an introduction of Criollo cocoa to India from Ambon in the Moluccas in 1798 (Ratnam 1961).

The greater bulk, if not the entire production, of cocoa in the

4 History and developmeni

sixteenth and seventeenth centuries was Criollo cocoa, but during the eighteenth century Forastero cocoa began to be grown and used. The first countries to produce Forastero cocoa were Brazil and Ecuador. There have always been many wild cocoa trees in the Amazon basin and when exports began in the eighteenth century much of the cocoa was collected from wild trees known as cacao bravo. The planting of cocoa in the Amazon basin started in the seventeenth century, but plantings suffered from severe shortages of labour and transport so that cultivated cocoa formed only a small proportion of Brazil’s production. Exports from Para, the State through which all exports from the Amazon area passed, were 1,000 tonnes by the end of the eighteenth century, reached 2,000 tonnes by 1820, and rose to 4-5,000 tonnes by 1870-80 (Alden 1976).

The first plantings in the State of Bahia were said to have been made in 1746 by a French planter bringing seeds from the State of Para. This introduction, which is thought to have been derived from wild Amelonado cocoa in the Guianas, gave rise to the relatively uniform type called Comum in the State of Bahia. Several decades passed before cocoa planting expanded and it was not until 1825 that any was exported. Production remained at a low level until the end of the’nineteenth century when a rapid increase took place.

In Ecuador there is no firm evidence of cocoa cultivation until the seventeenth century. Restrictions on trade discouraged expansion and production was only 1,000 tonnes in 1800. The cocoa planted was the Nacional type, which is peculiar to Ecuador and presumably arose from wild trees selected for seed for the earliest plantings. Cocoa planting started to expand early in the nineteenth century making Ecuador the largest producer, a position held for nearly 100 years.

Following the independence of Brazil, cocoa of the Amelonado type was taken from Bahia to S2o Tome in 1822. From there it was taken to Fernando Po in 1855 and later in the century to Ghana and Nigeria to form the basis for cocoa growing in West Africa.

Growth of consumpti,on

The original ‘chocolatl’ consumed in Central America has been described. Such a drink was unpalatable to Europeans. Josephus Acosta (1604) said that chocolate as drunk in Mexico is ‘loathsome to such as are not acquainted with it, having a skumme dr frothe that is very unpleasant to taste‘. The Spaniards made the drink more palatable by mixing the cocoa paste with sugar and seasoning it with cinnamon and other spices. It was this type of drink which later became popular in Europe, first in Spain, later in Italy, Flanders, France and England. At first Spain maintained a monopoly of trade

Growth of consumption 5

with the New World but this broke down when the Dutch captured Curacao enabling the trade in cocoa beans and their use to spread.

Some of the early literature on chocolate made extravagant claims for its medicinal properties. Thus the title page of J . Wadsworth’s Chocolate or an Indian Drink continues ‘by the wise and moderate use whereof health is preserved, sickness diverted and cured, especially the plague of the guts, vulgarly called the new disease, fluxes, consumption and coughs of the lungs with sundry other desparate diseases. By it also conception is caused, the birth hastened and facilitated, beauty gain’d and continued’ (Wadsworth 1652). What more could be claimed? This book was published in 1652, the printer ‘dwelling near the Vine Tavern in Holborne where the tract together with the chocolate itself may be had at reasonable rates’. This is one of the earliest references to chocolate being available in London. The book was a translation from Spanish of a trea- tise on chocolate by Colmenero, which was published in 1631 and subsequently translated into several languages (Colmenero 1631). Opposite opinions were expressed by other writers who claimed that cocoa inflamed the passions, and they coupled chocolate with novels and romances as things to be treated with caution by the fair sex. Whatever may have been the effect of these various claims on the readers, consumption was very small because the price of chocolate was high, owing largely to the heavy duties levied on imports of cocoa beans and chocolate. During the seventeenth and eighteenth centuries consumption in London was largely confined to chocolate houses frequented by the wealthy.

Early in the nineteenth century duties were reduced and consumption increased. During the 1820s imports of cocoa beans to Great Britain rose from 250 to 500 tons. The only product at that time was a chocolate drink made from the whole bean which was roasted, ground and mixed with sugar. Over half the production was used by the Navy, possibly as an alternative to rum. (At a later stage the value of such a nourishing drink to the men on watch was appreciated and the same Navy cocoa continued to be made until after the Second World War.) This chocolate drink was the only cocoa product made until 1828 when Van Houten used a press to remove some of the cocoa butter. This process was the first of the major technical advances which have led to the wide variety of cocoa products available today. The separation of the cocoa butter from the cocoa bean produced a powder containing 22-25 per cent fat which was easier to prepare and digest. Previously, various types of flour or starch had been added to the chocolate to make the drink less fatty, more palatable and of course cheaper. The new products were often sold as ‘homeopathic’ or ‘soluble’ cocoa, though it should be emphasised that cocoa powder does not dissolve. When cocoa powders were produced some manufacturers emphasised the purity

6 History and development

of this new product and there was an outcry against cocoas adul- terated with flour or starch.

The availability of cocoa butter led to the making of chocolate as we know it today which is basically composed of the dried cotyledons or cocoa nib, sugar and added cocoa butter, the addition of the extra cocoa butter making it easy to mould. Thus it became possible to make a chocolate bar of good appearance and texture and to cover other confections with chocolate. The inventor of chocolate is unknown, but Fry’s sold a ‘chocolat dklicieux a manger’ in 1847 and Cadbury Brothers were selling a similar product two years later. The other major technical development was the mixing of milk solids with cocoa mass and sugar to make milk chocolate which was invented by Daniel Peter of Vevey in Switzerland and was first introduced in 1876. The Swiss had a virtual monopoly of milk chocolate until Cadbury’s Dairy Milk chocolate was introduced in 1904. The growth of consumption of milk chocolate in a variety of forms has been the most striking feature of the cocoa and chocolate industry during the present century and today this product forms the backbone of the chocolate industry throughout the world.

Development of cocoa production since 1900

The growth of world cocoa production since 1850 is shown in Table 1.1. Reliable statistics of production or exports are only available since 1894 so the figures for 1850 are estimates. However the table shows the enormous growth of production over 130 years and also indicates the extent of the swing of production from South America and the Caribbean to West Africa. This is shown more clearly in Table 1.2. Central and South America declined gradually in importance for about 100 years but have recovered some of their importance recently. This is due largely to rapidly increasing production in Brazil which supplied the same proportion of world production in 1980 as it did in 1850. The proportion from the West Indies started to decline in 1900 and continues. Africa has, of course, shown a spectacular increase until about 1960 but has declined since.

The other great change that has taken place concerns the type of cocoa grown. The broad division between Criollo and Forastero has been explained, the Forastero group being largely represented by Amelonado in West Africa. In addition hybrids between the two major types led to Trinitario populations grown mostly in the Caribbean area, but also in Cameroon and Papua New Guinea. The cocoa market distinguishes two major categories of cocoa beans: bulk or ordinary cocoas coming from Forastero trees and giving a good strong chocolate flavour when suitably prepared; and fine flavour cocoas produced from Criollo or Trinitario trees. While the

Development of cocoa production since 1900 7

Table 1.1 Growth of cocoa production 1850-1980

Country Production (000 tonnes)

1850 I900 I940 I980

Brazil Colombia Ecuador Mexico Venezuela

Dominican Republic Grenada Trinidad

Cameroon Equatorial Guinea Ghana Ivory Coast Nigeria Sio Tom6

Malaysia

Papua New Guinea

Others

3.5

5.5

5.4

-

-

-

1.7

1.9

18 3

23 1 9

7 5

12

1 1 1

17 -

17

13 1 12 14 2

17

20 3 8

23 13

24 1 43

103 5

37

349 39 81 30 14

32 3 2

120 8

258 403 I55

8

43

28

91

World total 18 115 612 1,664

SOURCES: 1850 figures: Gordian, Essays on Cocoa, 1936; later figures: Gill and Duffus, Cocoa Statistics, April 1981 and May 1983.

Table 1.2 Movement of cocoa production

1850 1900 1920 1940 1960 1980

Total production (000 tonnes) 18 115 371 672 1,189 1,664

Proportion (70) from: Central and South America 80 51 30 28 21 32 West Indies 14 27 20 6 4 3 Africa - 17 48 6.5 73 60 Asia 4 2 1 2 5 -

Criollo beans give a mild or weak chocolate flavour, the Trinitario beans usually give a good chocolate flavour together with some fruity ancillary flavour. One anomaly in this broad division is the Cacao Nacional of Ecuador where cocoa of a distinctive fine flavour type is produced from the Nacional trees which are considered to be a Forastero type; another anomaly is Cameroon cocoa, produced from Trinitario trees but classed as a bulk cocoa.

In 1850 the fine or flavour cocoas formed 80 per cent of total production. By 1900 the proportion had fallen to 40-45 per cent and


since then the proportion has continued to fall steadily. By 1977/78 the production of cocoa from the traditional ‘fine flavour’ countries was 106,000 tonnes or 7.2 per cent of world production. To this figure should be added the production of Papua New Guinea, a newcomer to the ‘fine flavour’ producers, which would raise the proportion to 9 per cent. However a distinction must be drawn between production from fine flavour producers and the production of fine flavour cocoas. The latter is very much less because fine flavour cocoas are sold by mark rather than by country of origin and only a proportion of each country’s production is sold on the fine flavour market. The situation differs from country to country, but it is probably true to say that the proportion of cocoa classified as fine flavour emanating from each fine flavour producer has fallen over the past fifty years. The total production of fine flavour cocoas was estimated at 30,000 tonnes in 1977 or only about 2 per cent of world production (Wood 1977).

In the past fine flavour cocoas were referred to as cocoa of good quality while bulk or ordinary cocoas were often described as poor quality. It was probably true that Criollo and Trinitario cocoas were generally of better quality, that is, better prepared than Forastero cocoas but intrinsically there is only a difference of flavour. Now- adays the quality of Forastero cocoas is as good as the quality of fine flavour cocoas.

General characteristics of the cocoa crop

In the New World cocoa is cultivated on plantations and on small- holdings but plantations of 20 ha and upwards are the customary units. In Trinidad plantations are relatively small, few exceeding 120-160 ha, but in Brazil and Ecuador some much larger plantations have been established. In practically all cases the plantations were originally planted by individuals or family owners, but there are a few places in the West Indies and Latin America where cocoa has been planted by plantation companies. In Costa Rica, for instance, large plantings of cocoa were made by the United Fruit Company, the cocoa being planted after the failure of bananas owing to Panama disease; these plantings were subsequently split into small individual farms. There have also been some large-scale plantation developments in Ecuador.

In Africa cocoa is grown almost entirely on small-holdings and it is usually stated that each farm is very small. It is true that individual plantings representing one year’s clearing are generally small - less than 1 ha - but there is little relationship between such plantings and the size of one farmer’s holding. Polly Hill (1962) has made it clear that in ‘Ghana the size of farmers’ holdings and the manner

References 9

in which the farms are held vary enormously; any generalisation on this point would be unwise. In Nigeria the cocoa survey conducted by the Nigerian Cocoa Marketing Board in the early 1950s produced data which showed that the area of cocoa held by most farmers was only 0.6 ha; on the other hand ‘the bulk of the cocoa produced comes off farms with a good deal more cocoa land’, such farms being more than 2.5 ha in extent (Galletti et al. 1956). The same general picture is probably true of the other main cocoa-growing countries in West Africa - Ivory Coast and Cameroon - though there is less information available. In West Africa as a whole, therefore, the size of cocoa farms varies considerably but the majority of farmers hold relatively small areas and there are few farmers with more than 8 ha.

There are certain exceptions to this general picture. In West Cameroon several cocoa plantations were started by German companies before the First World War, but these have all been converted to other crops. In Equatorial Guinea most of the cocoa was produced on plantations. More‘ recently cocoa has been planted quite extensively on some plantations in the Congo, and in Nigeria cocoa is one of the crops grown on some state Agricultural Devel- opment Corporations’ plantations. In addition there are a few European-owned plantations in the Ivory Coast.

In the Far East cocoa is a relatively new crop and is being grown on public and private plantations as well as small-holdings in Malaysia and on privately-owned plantations and small-holdings in Papua New Guinea.

Cocoa has only recently become a crop grown by plantation companies. There are several reasons for this; first, cocoa was not grown on a large scale in those countries where plantation agriculture has been widespread; second, plantations are most successful where they grow a crop which requires heavy capital expenditure particularly for processing or will give better yields or achieve higher prices through skilled management. Cocoa does not require heavy capital expenditure on processing equipment; it can be processed on any scale. Furthermore, skill in processing cannot guarantee a higher price for cocoa. To be competitive with small-holdings, a cocoa plantation must achieve higher yields and ways of doing this are only now beginning to be developed.

References Acosta, J. (1604) Quoted in ‘Historicus’ Cocoa: all about i t . Sampson Low, Marston:

London, p 32. Alden, D. (1976) The significance of cacao production in the Amazon region during

the late colonial period: an essay in comparative economic history. Proc. Amer. Philosophical Soc. 120, 2: 103-35.


Bergmann, J. F. (1969) The distribution of cacao cultivation in Pre-Columbian

Colmenero, Antonio de Ledesma (1631) Curioso tratado de la naturaleza y calidad del

Cuatrecasas, J . (1964) Cacao and its allies. A taxonomic revision of the genus Theo-

Galletti, R., Baldwin, K. D. S. and Dina, 1. 0. (1956) Nigerian Cocoa Farmers.

Hill, Polly (1962) Social factors in cocoa farming. In J . B. Wills (ed) Agriculture and

Morris, D. (1882) Cacao: How to grow and how to cure it. Jamaica, 45 pp. Ratnam, R. (1961) Introduction of Criollo cacao into Madras State. S. Indian Hort.

Stephens, J. L. (1843) Incidents of Travel in Yucatan. Thompson, J. E. S. (1956) Notes on the use of cacao in Middle America. Notes on

Middle American Archaeology and Efhnology No. 128. Carnegie Institution of Washington. pp 95-116.

America. Annals of Assocn of Amer. Geographers 59: 85-96.

chocolate, dividido en quatro puntos. Madrid

broma. Contrih. U.S. Nut. Herb. 35, 6: 379-614.

Oxford Univ. Press, p. 149.

Land Use in Ghana. Oxford Univ. Press, pp 278-85.

9. 4: 24-9.

Wadsworth, J . (1652) Chocolate or an Indian Drinke. London. Wood, G. A. R. (1977) The markets for fine flavoured versus bulk cocoas. Risolah

Seminar Coklat, Surabaya 1977: 97-107 reprinted in Cocoa Growers’ Bull. 27: 5-11,

Chapter 2

Botany, types and populations H. Toxopeus, Foundation for Agricultural Plant Breeding, Wageningen, The Netherlands

Theobroma cacao was the name given to the cocoa tree by Linnaeus in the first edition of his Species Plantarum published in 1753. The genus Theobroma, together with the genera Herrania, Guazuma and Cofa, which occurs in Africa, belongs to the family Sterculiaceae.

The natural habitat of the genus Theobroma is in the lower storey of the evergreen rain forest. All the species of the genus are found wild in the rain forests of the western hemisphere from 18 O N to 15 “S, that is from Mexico to the southern edge of the Amazon forests. In this habitat rainfall is heavy, the temperature is relatively uniform throughout the year, there is constant high humidity and the shade is dense. Under these conditions T. cacao flowers sparsely and bears only a few pods.

Cuatrecasas (1964) divided the genus Theobroma into six sections containing twenty-two species. Theobroma cacao is the only species which is cultivated widely, the other better known species in the genus being T. bicolor and T. grandiflorum. Theobroma bicolor is atypical of the genus as its inflorescences appear in the axils of the new leaves so that its large heavy pods (Fig. 2.1) are borne on the ends of the branches which are bent down when the pods reach maturity. The beans have white cotyledons and are the size of small cocoa beans; they are called ‘pataste’ and have been used as an adul- terant of, cocoa in Central America. Theobroma grandiflorum, known as ‘cupuaqu’ in Brazil, is well liked locally for the delicate flavour of the mucilage around the beans (Fig. 2.2).

Theobroma cacao is a diploid species with a chromosome number of 20, and has been subdivided into two subspecies by Cuatrecasas (1964):

T. cacao spp. cacao consists of the Criollo populations of Central and South America. T. cacao ssp. sphaerocarpum includes all the other populations.

These populations are described in detail later in this chapter

12 Botany, rypes and populations

Fig. 2.1 Pod of Theobroma bicolor. Fig. 2.2 Pod of Theobroma grandiflor- SOURCE: Cuatrecasas (1964). urn. SOURCE: Cuatrecasas (1964).

Plant growth

The fruit, commonly known as a pod, contains the seeds embed- ded in mucilaginous pulp. This mucilage contains a germination inhibitor which delays germination inside the pod, but once the pod is opened the mucilage decomposes rapidly and germination begins because the seed has no dormant period. If ripe pods are left on the tree beyond maturity, the seeds are liable to germinate inside the pod, but healthy ripe pods can be harvested and kept unopened for 3-4 weeks without loss of viability. If the pods are opened, special measures, such as storing in charcoal or well-rotted sawdust, are needed in order to preserve viability. More details .of these measures, which are necessary for transporting seed, are given in the chapter on propagation.

On germination the rootlet grows out first and the hypocotyl raises the closed cotyledons about 3 cm above ground level. This first phase of development is sometimes referred to as the ‘soldier’ stage. There are no buds on the stem of the hypocotyl, a point of significance when budding, as budding below the scar left by the cotyledons will avoid any shoots arising from the stock.

The second phase of development begins with the opening of the

Botany, types and populations 13

PI. 2.1 Amelonado cocoa pods showing arrangement of beans (A. J. Beaks).

cotyledons, thereby exposing the plumule, and ends with the hardening-off of the first four leaves which have short internodes so that the leaves are at the same level. Subsequent growth occurs at inter- vals of approximately six weeks with leaves spaced out in a spiral arrangement. There is a bud in each leaf axil. Vertical growth continues until the plants reach a height of 1-2 m at which point the plant enters its third growth phase when vertical growth ceases and, on the terminal end of the stem, five buds with very short internodes grow out sideways simultaneously. The point at which this occurs is called the ‘jorquette’. The side branches which grow at an angle of 0-60 O to the horizontal, have an alternate leaf arrangement and are called ‘fan’ branches. Thus growth is dimorphic, the vertical stem being orthotropic and the fan branches plagiotropic.

If the apical bud is damaged prior to jorquetting, buds lower down on the top part of the stem will grow out, all with an upright growth habit and spiral leaf arrangement. These shoots are called ‘chupons’ and each is capable of forming a jorquette in due course.

After some years of growth chupons may develop on the trunk just below the jorquette and this is more likely to occur when light penetrates the canopy and strikes the jorquette. These chupons will eventually reach above the tree’s canopy to form new jorquettes which, in time, may take over the canopy, the first jorquettes ulti- mately dying off. This process may be repeated several times and as a consequence the canopy becomes higher (Fig. 2.3). In a farm or cocoa plantation trees will grow to a height of 4-10 m depending on spacing and the degree of shade. In the wild under the heavy shade of the primary forest they may grow to 20 m. Chupons also arise from the base of the trunk and can be used to replace the main

14 Botany, types and populations

PI. 2.2 Young cocoa plant showing jorquette (G. A. R. Wood).

stem if a tree falls over. Chupons may occasionally arise on a fan branch. Budwood or cuttings taken from chupons will give rise to plants with an upright growth habit, while vegetative material from fan branches will grow out sideways.

Leaves The leaves also show dimorphic characters corresponding ’ to the different types of stem on which they arise. On chupons, the first leaves have long petioles and are symmetrical; the petioles have a marked pulvinus or swelling at each end which allows the leaf to be orientated in relation to the light. The leaves on the fan branches have shorter petioles and are slightly asymmetrical.

Leaf production on the fan branches is by a series of ‘flushes’, during which the terminal bud grows out rapidly, producing three


PI. 2.3 Young cocoa tree with jorquette PI. 2.4 A seven-year-old cocoa tree and five fan branches, bearing cherelles and pods (G. A . R. Wood).

grown from a fan cutting (D. H . Urquhart).

to six pairs of leaves, which may be pale green or various shades of red. They are soft and delicate, but gradually ‘harden’ and assume, on the fan branches, their typical orientation. Red-pigmented leaves also become green during hardening. After the flush has expanded, the terminal bud remains dormant for a period determined by various environmental factors and then produces another flush of growth.

Development of a new flush leads to a demand on nutrients which is partly met by translocation from the older leaves. This leads to leaf fall, hence the description of flushing as ‘change of leaf‘. The extent to which the old leaves are lost when flushing occurs is a good indication of the state of nutrition of the tree.

Flushing in mature trees is stimulated by environmental factors. At one time it was thought that temperature was the main controlling factor but it is now clear that moisture stress is also very important. Studies in Brazil showed that periods of bud-bursting and subsequent leaf expansion were always associated with a previous period of moisture stress (Alvim 1977). If rain does not occur soon after bud-burst has been initiated the buds may not develop, but rain will ensure a vigorous flush. Cocoa trees which are unshaded flush more intensively than shaded cocoa and this is probably due to higher internal moisture stress and higher ambient temperature.

The leaves have stomata on their under surface only. Their number per unit area is affected by the light intensity which also

16 Botany. types and populations

Fig. 2.3 Stem growth of cocoa tree. A . Adult seedling with jorquette and five fan branches. B. Older tree of three storeys with basal chupon. SOURCE: Cuatrecasas ( 1964).

I I\ n I'

0 -

cm

B C

Fig

. 2.

4 R

oot

deve

lopm

ent.

(A)

Seed

ling

4-5

wee

ks o

ld;

(B)

Seed

ling

4 m

onth

s ol

d; (

C) 3

-yea

r-ol

d tr

ee.

SO

UR

CE

: Van

Him

me

(195

9).

a

9

'D s E

e F' 2


influences the size and thickness of leaves. Those that develop under shade are larger and greener than those that grow in full sun.

Root system The root system of the mature tree consists of a tap-root 120-200 om long with an extensive system of lateral feeder roots most of which lie in the top 20 cm of the soil, but which may extend to 40-50 cm where the hurnic layer is deep. The lateral roots grow far beyond the limit of the tree’s canopy forming an intricately woven mat. At the tip of the main lateral roots there are bunches of fine rootlets which are especially abundant where plant residues are rotting (McCreary et af. 1943).

A major study of the root system was carried out in Zaire by van Himme (1959). This work showed that the tap-root develops rapidly after the seed germinates, growing from 1 cm in length after 1 week to 16-18 cm after 1 month and 25 cm after 3 months. Thereafter the rate of growth declines and it takes 2 years for the tap-root to reach 50 cm. The tap-root divides and has some small rootlets at its extremity which indicates that the tap-root absorbs water and nutrients. The growth of the root system is illustrated in Fig. 2.4(A)-(C).

The cocoa plantation As the trees develop, the foliage and branches of neighbouring trees will grow together to form an integrated canopy unless the spacing is too wide. Such a canopy is vital for high yields which are always associated with a dense canopy and a light overhead shade (Fig. 2.5). This is because large amounts of biochemical energy are required for the conversion of the carbohydrates produced by photosynthesis into fat which is accumulated in the developing beans. The interaction of shade and nutrients on yield are discussed in the chapter on that subject.

Flowers The flowers are formed on the trunk and branches, a habit referred to as cauliflorous or truncate. The flowers are only produced on wood of a certain minimum physiological age, which is usually two or three years old under good growing conditions and they are quite small, about 15 mm in diameter. They are borne on long pedicels and have 5 free sepals, 5 free petals, 10 stamens and ovary of 5 united carpels. The floral formula is K5 C5 A5 +5 G(5); and is illustrated in Fig. 2.6. The petals have a curious shape; they are very narrow at the base but expand into a cup-shaped pouch and end in a broad tip or ligule. The ten stamens, which form the androecium or male part of the flower, are in two whorls, the outer whorl consisting of


Fig. 2.5 The ideal cocoa plantation. SOURCE: Toxopeus (pers. comm.)

Fig. 2.6 Floral diagram of Theobroma cacao. SOURCE: Cuatrecasas (1964)

five long non-fertile staminodes, the inner whorl five fertile stamens. The stamens bear two anthers which lie in the pouch of the corresponding petal (Fig. 2.7). The ovary has five parts containing many ovules arranged around a central axis. The style has the appearance of a single style and is about twice as long as the ovary. The flowers are generally pink with darker tissue in the staminodes and the petals, but there is considerable variation between cultivars in the size and colour of the flowers. The inflorescence primordia arise from old leaf axils and it takes about thirty days from initiation for the bud to emerge through the bark and mature.

20 Bolany, types and populations

Fig. 2.7 A cocoa flower. SOURCE: van Hall (1932).

When a bud matures the sepals split during the afternoon and continue to open during the night. Early the following morning the flowers are fully open and the anthers release their pollen. The style matures a little later. This is the best day for pollination and failure of fertilisation on this day will cause the flower to absciss the following day. This is the only stage in the development of the pod at which abscission occurs (Zamora et al. 1960).

Cocoa trees produce large numbers of flowers at certain times of the year depending on local conditions and type. Only 1-5 per cent of the flowers are successfully pollinated to produce a pod, although higher proportions have been recorded for the Amelonado type (Posnette and Entwistle 1958). A proportion of the flowers, and hence the pods, are borne on the trunk and main branches, the remainder being borne on the branches of the canopy, but the proportions vary according to the cultivar. Leaf axils which have produced flowers and pods for several years become thickened and are then called flower cushions.


Pollination

Pollination, the process of depositing pollen on the style, is effected by various small insects. The most important group of pollinating insects are midges belonging to several genera of the family Cera- topogonidae. A number of species of the genus Forcipomyia are the commonest pollinators. These midges are so small that they are difficult to see and are called ‘no see ’ems’ in the West Indies. This makes the study of these insects extremely difficult and knowledge of them remains scanty. Cocoa flowers are visited by many other insects including ants, aphids, fruit flies (Drosophila spp.) and thrips. Some of these have been thought to be involved in pollination but the evidence is not conclusive and their part, if any, is considered to be minimal (Winder 1977).

Insects visiting cocoa flowers will collect pollen on their thoracic hairs whilst feeding on the dark purple guide-lines on the petal which lead to the anthers resting inside the petal hood. While leaving the petal the insect may crawl down the inner surface of the staminodes rubbing off pollen grains onto the style. On freshly opened flowers the staminodes are parallel with the style and pollination will be effected, but as the flower ages the staminodes bend away from the style, thereby preventing pollination (Kaufmann 1975).

The pollinating midges require cool, dark, moist habitats and breed in rotting vegetation, including heaps of cocoa husks. Their life-cycle is about twenty-eight days and the population builds up during the rainy season. Both sexes are involved in pollinating cocoa flowers, but the greater part is effected by the female midges and pollinating activity is greatest soon after dawn and in the evening. During these periods they may fly for a distance of up to 50 m, but studies in Ghana and Nigeria showed that most pollination takes place between neighbouring trees (Posnette 1950, Voelcker 1940).

The effect of applying pesticides to cocoa trees on the population of pollinating midges has been studied several times and the general conclusion is that any reduction of the population is short-lived. The various large-scale spraying experiments to test pesticides for mirid control in West Africa did not give any indication of negative side effects on the population of pollinators resulting in reduced yields. A recent study in Cameroon showed that fogging with HCH affects the population for 1-2 days while the effect of spraying may last up to 8 days (Lucas and Decazy 1981). Similar results with other pesticides have been reported and were summarised by Winder (1977).

Attempts have been made to effect pollination by blowing air over the flowers with a mist-blower. Trials in Brazil and Costa Rica using this technique on self-compatible varieties have resulted in increases in yield of up to 100 per cent in Brazil (Soria et al. 1980)


and even greater increases in Costa Rica. In the latter trials the number of beans in pods resulting from mechanical pollination was well below normal and this caused the pods to have abnormal shapes (Knoke et al. 1980). While mechanical pollination might be used where natural pollination of self-compatible trees is inadequate, it cannot be applied to self-incompatible trees.

Pollination by flying insects results in approximately 25-50 per cent cross-pollination on self-compatible trees but the proportion of flowers pollinated is comparatively low (Posnette 1950, Voelcker 1940). After the pollen is deposited on the style, the pollen grains ‘germinate’ and pollen tubes containing the male gametes grow through the stylar tissues into the ovary and pass through the very small opening into an ovule. Here the male gamete meets the female and fertilisation will occur provided the two gametes are compatible. The fused gametes form the zygote, from which the seed develops. However, a certain minimum number of individual fertilisations must occur for a pod to be able to grow. This number is about 20 k 10, varying according to the cultivar (Toxopeus and Jacob 1970).

Incompatibility This is a well-known phenomenon occurring in cross-fertilising plants which was first reported in cocoa by Pound (1932). He showed that certain trees in Trinidad could not set fruit with their own pollen nor with one another’s. Since then the existence of self-compatible and self-incompatible trees has been established in most cocoa growing countries, but self-incompatible trees are often cross-compatible.

In many plants incompatibility occurs in the style or stigma, preventing the development of pollen tubes, but in cocoa the mechanism is different. The pollen tubes develop normally in all cases, but when the mating is incompatible the male gamete does not fuse with the female gamete.

A genetic mechanism controlling the fusion of gametes has been proposed, consisting of a series of S-factors. Cope in Trinidad proposed five different S-factors or S-alleles to explain the results of extensive selfing and crossing between many cultivars (Cope 1962) The dominance relations of these alleles are expressed in the following formula:

Sa = Sb = Sc > Sd > Sf.

Previously Knight and Rogers had studied the compatibility relations within a few families of Amazon material in Ghana (Knight and Rogers 1955). They too postulated five factors to explain their results but the dominance relations were different:

s, > s2 = s3 > s4 > ss.

Botany, iypes and populations 23

Both sets of relationships may well exist in different populations but no further studies have been reported.

In an incompatible pollination the proportion of non-fusion between the gametes will be 25, 50 or 100 per cent. In all cases the ovary will fail to develop and the flower falls off three or four days after pollination.

The degree of incompatibility varies between different populations. Amazon cultivars are all self-incompatible but are generally cross-compatible. Trinitario cultivars have a high proportion of self- incompatible trees which will not cross with other self-incompatible trees, requiring pollen from self-compatible trees for successful pollination. The Amelonado population is entirely self-compatible. In some Trinitario populations cross-incompatibility may have been a limiting factor on yield. This risk is avoided with modern hybrids by ensuring that a mixture of several different hybrids are planted.

Self-incompatibility is made use of in the design and operation of seed gardens to ensure that seed of a certain parentage is produced. This is described in the chapter on propagation.

Pod growth and cherelle wilt After pollination the pod grows slowly for about 40 days, after which growth becomes more rapid and reaches a maximum at about 75 days. Between 40 and 50 days after pollination, the zygote, the product of the fusion of the gametes, and only a single cell in an ovule, makes its first division to become the embryo. A second growth period starts about 85 days after pollination when pod and ovule growth slow down at the expense of embryo growth. The ovule is filled with a jelly-like endosperm which is consumed by the embryo about 140 days after pollination. During this period there is a rapid accumulation of fat. When embryo growth ceases there is no further resumption of pod growth and ripening begins almost immediately. It takes 5-6 months from pollination to ripening (McKelvie 1956).

Despite the fact that only a small percentage of the flowers is successfully pollinated, too many fruits are normally set for the tree to carry through to maturity. Like all other tree crops, cocoa has its fruit thinning mechanism but the ‘cherelles’ (young fruits) to be shed do not fall off, they first stop growing and a week later turn yellow and then blacken and shrivel, but remain on the tree. This phenomenon is called cherelle wilt and occurs during the first half of the period of development of the pod. The incidence of wilt increases from pollination to a peak at about 50 days, then falls off and rises to a second peak at 70 days. After 95-100 days no further wilting takes place (McKelvie 1956). The percentage of cherelles that wilt is highly variable. Not all the losses of cherelles are due to cherelle wilt, but diagnosis of the cause is often difficult. A good

24 Borany. types and populations

proportion may be lost to Phytophthora pod rot and other causes (Thrower 1960).

Developing pods are called cherelles until the stage at which no further wilting takes place. They then become immature pods until they reach full size when they become mature and finally ripe pods. The mature fruit or pod is botanically an indehiscent drupe which remains on the tree unless harvested. Natural dissemination depends on monkeys, rats or squirrels making a hole in the pod to extract the beans and suck off the surrounding pulp, dropping the seed on the ground.

The husk varies appreciably in thickness and in degree of ligni- fication between different cultivars and inside the husk the beans are attached to a placenta. Each bean is surrounded by a mucilaginous pulp. The number of beans per pod is usually between 30 and 40, but a range as wide as 6-50 from one cultivar has been found (Toxopeus and Jacob 1970).

Each seed or bean consists of two convoluted cotyledons and a small germ, all enclosed in the testa. The colour of the cotyledons varies from white to dark purple. Pods from crosses between white- beaned and purple-beaned trees contain either 50 per cent or 100 per cent purple beans (Wellensiek 1932).

Physical characters of the bean The dry weight of the bean is mainly determined by the tree that produces it, but the pollen-parent also affects weight to a small extent. The main environmental factor that affects bean weight is rainfall. In Nigeria it has been shown that the rainfall 2, 3, 4 and 5 months before harvesting the pods is significantly correlated with the average weight of dried beans (Toxopeus and Wessel 1970).

The fat content of the bean is normally expressed as a percentage of the dry nib (cotyledons) and may be between 45 and 65 per cent depending on genotype. It has been shown to be influenced by the male as well as the female parent (Beek et al. 1977). There is a positive correlation between bean weight and fat content.

The shell is the product of testa and remnants of mucilage after fermentation and drying. The shell content is expressed as the percentage weight of shell over total bean weight. As the size of bean increases, the surface to volume ratio decreases, reducing the shell percentage. This is a general rule that applies to beans of a certain cocoa variety, but different cultivars may vary in thickness of the testa and may produce different amounts of mucilage, but reliable information on these characters is lacking. Shell content of beans produced at the end of a long dry season has been shown to be higher than that of beans of the same size produced in the wet season (Toxopeus and Wessel 1970). The shell content is also influenced by methods of fermentation and drying.

Types and populations 25

PI. 2.5 A cocoa farm in West Africa (G. A. R. Wood).

Types and populations

As with the fruit of all cultivated plants, cocoa pods show a great deal of genetic variation. Ripe cocoa pods vary considerably in length from 10-32 cm and also in shape, surface texture and colour. The shape varies from nearly spherical to cylindrical and the surface from warty and deeply furrowed to nearly smooth. At one time it was thought that the shape of the pod was an indication of quality of the cocoa bean and various shapes were named; the following names are arranged in descending order of quality (Fig. 2.8):


Fig. 2.8 Venezuela; (D) Angoleta. SOURCE: Cuatrecasas, 1964.

Examples of pod shapes. (A) Cundeamor; (B) Criollo; (C) Amelonado from

Angoleta - deeply ridged, warty, square at the stalk end; Cundeamor - similar to Angoleta but characterised by a bottle

Amelonado - smooth, shallow furrows, melon shaped with a

Calabacillo - small and nearly spherical.

neck;

blunt end and slight bottle neck;

These names were used in the pre-war literature, but the connec- tion between pod shape and quality has not been substantiated and,

Types and populations 27

with the exception of Amelonado, these names have largely gone out of use.

Certain morphological characters of pods and beans are used as the basis of classification into categories which may be called varieties, cultivars, types or populations. Cocoa is best classified in terms of types and populations because these concepts are not associated with uniformity as are the other terms. Variation is to be expected in view of the outbreeding nature of the species and most cocoa populations show a degree of variation. Some exhibit extreme variation in pod and bean characters, and are indeed characterised by this variation.

When attempting to classify a population of cocoa trees it is important to gather information on the following points:

1. A population should be described on the basis of the pod and bean characters of a random sample of at least ten, and prefer- ably more, trees (see Table 2.1).. This will lead to a statement of the degree of variation of characters.

2. Information on the history of any introductions should be studied so as to assess the possible effects of introductions on the original population.

Defining a population should not be confused with the detailed morphological descriptions of individual trees or clones for a clone catalogue, the purpose of which is to serve breeders as a check on the clones they introduce from different countries (Soria and Enriquez 1981).

The appearance of the pod, or its morphology, plays an important role in the definition of types and populations. Pod morphology is determined by a combination of characters of independent inheri- tance. Pods from the same tree or from the same clone are identical but there may be great differences between trees and between clones.

1. Surface. The pod has ten ridges of which five alternate ones are more pronounced than the others; the ridges may be very shallow to deeply furrowed. The surface may vary from smooth to warty;

2 . Bottle neck. A basal constriction may be present or absent; when present it may vary from pronounced to inconspicuous and the shoulder may vary from broad to narrow (Fig. 2.9);

3 . Point or apex. A point may be present or absent and when present it may vary from long acute to blunt and indented as shown in Fig. 2.9;

4. Colour. The colour of the developing pod may vary between a very pale green (blanco) to dark green, and red to deep purple and all possible combinations of these basic colours. In intermediate cases the colour of the pod may be described as ‘splashes


Bottleneck or basal constriction

nnnhfi 0 Absent 1 Slight 2 Intermediate 3 Strong 4 Wide shoulder

Point or apex form

1 Attenuate 2 Acute 3 Obtuse 4 Rounded 5 Mammelate 6 Indented

Fig. 2.9 Shapes of neck and point of pods. SOURCE: Anon. 1981.

of red on a white or green base’, indicating that the ridges are red and the furrows pale green or green. When the pod ripens, green pods turn yellow and red ones turn orange.

Criollo, Forastero and Trinitario

The names Criollo, Forastero and Trinitario indicate the three main types or groups of populations of T. cacao as proposed by Cheesman (1944). The distinguishing characters are stated in Table 2.1 and used together these characters will classify populations adequately.

Criollo (Theobrorna cacao L. ssp. cacao Cuat.) The main characters of the Criollos are stated in Table 2.1. The beans ferment quickly and in the past were reported to have a highly regarded, but usually weak, chocolate flavour. Criollos typically lack vigour and the jorquette, if formed at all, consists on average of three fan branches with small leaves. Criollos are reported to be extremely susceptible to diseases like bark canker (Phytophthoru spp) and Cerutocystis and will not survive persistent attack on their foliage by mirid bugs. The Criollos were probably domesticated by the Mayas and can now be subdivided into two geographical groups: (a) Central American Criollos and (b) South American Criollos. There is historical evidence that the latter group was introduced into the north-eastern part of South America by monks of the Capuchin

Criollo, Forastero and Trinifario 29

Table 2.1 Main distinctive characters of Criollo. Forasfero and Trinifario

Criollo Forastero Trinifario

Pod husk Texture Soft Hard Mostly hard Colour Red occurs Green Variable

Beans Average no. per pod 20-30 30 or more 30 or more Colour of cotyledons White, ivory or Pale to deep Variable, white

very pale purple purple beans rarely occur

order (Pittier 1935, Soria 1970). Criollos dominated the market until about the middle of the eighteenth century and accounted for most of the exports to Europe. This position was lost rapidly in the ensuing seventy years and today only a few, if indeed any, pure stands still exist.

Soria (1970) describes the following types:

Mexican Criollo This is a variable type that occurs only as scattered stands in a few plantings in the state of Chiapas. The shape and size of pods and beans is very variable, the bean colour is invariably white. The colour of the pods is between green and a clear red, and they always have a pointed tip.

Pentagona or Lagarto Within Criollo and Trinitario plantings in Mexico and Guatemala, trees are occasionally found showing pods with very thin, leathery husks; they are warty with only five angular ridges, are red or rarely green and contain seeds of varying shades of purple.

Nicaraguan Criollo or Cacao Real Small plantations or isolated groups of this type still appear to exist in certain areas of Nicaragua. The main feature of this variable type is the intense red colour and very pronounced bottle neck on the pods.

Colombian Criollo Pound (1938) described a green podded and a deep purple podded type, both smooth and each type quite uniform. Soria (1970) mentioned that very few plantings resembling Mexican Criollo remained in existence in Colombia.

Forastero (Theobroma cacao L. ssp. shaerocarpum Cuat.)

This is a large group that contains cultivated, semi-wild and wild


populations, of which the Amelonado populations are the most extensively planted.

Amelonado The vast cocoa areas in the State of Bahia, Brazil and in West Africa (except Cameroon) are predominantly of a strikingly uniform type called Amelonado. The pod is light green and smooth; ridges, bottle neck and point are present but not pronounced. The average number of beans per pod is around forty and beans are dark purple. It is a hardy and productive type, although it is slow to come into production by present-day standards. Amelonados are typically uniform in all characters.

Comum The cocoa industry of Bahia was reportedly initiated with plant material introduced in the late 1700s from the lower Amazon region and until recently roughly 90 per cent of the mature plantings were of the Comuy variety with typical Amelonado pods.

Some trees may be found with slightly different pod shapes, but all are green and smooth. The ‘Para’ variety has a more rounded Calabacillo pod, and the ‘Maranhiio’ a more elongated pod that has a more pronounced bottle neck and ridges (Soria, 1970).

West African Amelonado In 1824 the Portuguese successfully transferred a few plants from Brazil across the Atlantic to the island of Siio Tom6 just off the African mainland opposite Guinea. SCo Tom6 was a major exporter of cocoa by the end of the century and the main cocoa variety today is very similar to the Comum, but is commonly referred to as West African Amelonado.

Towards the end of the 1850s plants were introduced from Siio Tom6 to the island of Bioko, formerly Fernando Po, now part of Equatorial Guinea. Major cocoa plantings developed and the island became an exporter from the turn of the century. The variety is again typical West African Amelonado. Here the industry developed initially with liberated slaves and subsequently with migrant labour from the West African mainland. The returning labourers took cocoa pods to their various homelands and attempted to grow the crop. This was how cocoa planting started in Ghana and Nigeria and in both countries the cocoa trees were a typical West African Amelonado. Cocoa in the Ivory Coast and Togo developed later and is also of this variety.

Cacao Nacional This is the name of the old variety of Ecuador, but following the onslaught of witches’ broom disease in the 1920s it hardly exists

Criollo, Forastero and Trinitario 31

today. The distinctive ‘Arriba’ flavour of Ecuador cocoa was attributed to the Nacional variety which produces large pale purple beans. The pod is large and green with a rough surface and fairly deep ridges, the bottle neck and point are not pronounced. It is generally considered to be an Amelonado type. Nowadays the main cocoa type in Ecuador is Trinitario as a result of introductions from Trinidad and Venezuela.

Matina or Ceylan Grown in Costa Rica and Mexico respectively, this is the Amelonado of Central America, probably of a common origin, which may well have been Brazil or Surinam (Soria 1970).

Guiana wild Amelonado First discovered and reported by Stahel (1920) in the forests of Surinam towards the western border. He describes extensive stands of large multi-stemmed cocoa trees.growing under the huge trees of the primary forest. The pod shape is uniform and typically Amelonado, the seeds are of Amelonado size and shape but their colour is bright violet and there is little bitterness in the taste; the pulp is very aromatic; it is estimated that about thirty-one pods would be required to produce 1 kg of cured beans. All trees were heavily infected with witches’ broom disease. These findings were followed up by Myers (1930) who visited the wild cocoa discovered by Stahel and managed to take some live seeds to Trinidad where the resulting trees became known as ‘Surinam wild’. Visits to the border area of Guyana and Brazil by Myers (1934) confirmed the general occurrence of this variety of wild cocoa in the forests of western Guyana.

Amazon populations described by Pound (1938) These encompass all the populations described and collected by expeditions in the vast Amazon river basin, but the picture is far from complete. Until recently the main objective of all expeditions to the Amazon basin was to find trees that might be resistant to witches’ broom disease and to collect planting material from them. Apparently resistant trees were found to occur more or less frequently in the upper Amazon area around and to the west of Iquitos. The purpose of more recent expeditions has been to obtain a fuller picture of the diversity of the population in the upper Amazon area and to collect representative material.

In the Amazon basin as a whole the pod colour is pale to dark green except for a few reports from the western extremity of the area where the Nap0 river extends into Ecuador. Splashes of red have been reported on the pods of some trees and Pound (1938) states that this occurs in a population he referred to as ‘Criollo de la montagne’ which probably meant ‘the native cocoa in the


forest’ (montana). The pod shape and texture of the husk is quite variable. The colour of the cotyledons is mostly dark purple, but occasionally the cocoa found in the upper reaches of the Amazon basin is reported to contain pale purple beans. Some of the trees found o n the Nap0 referred to above, with splashes of red on the pod, were also reported to segregate white beans.

Pound (1945) describes the variations in the pod characters found in the Amazon basin as follows:

Passing westwards from Belem de Para there is not much variation in the central type of Brazilian Amelonado pod until one reaches the Solimbes, or middle Amazon, above the junction of the Rio Negro. It thus appears probable that the dominant Brazilian type occurs in the whole of the lower Amazon valley and the Guianas to the North.

In the middle Amazon which stretches from the Rio Negro to the Rio Ucayali the central type changes perceptibly. The pods are still completely unpigmented but longer and more corrugated and often definitely warty. Sometimes a pronounced bottle neck appears. The shell may be thicker and the pod approaches the Cundeamor type in places. The seeds though still relatively small and uniformly purple in colour are plumper than those of the lower Amazon.

Above Iquitos on the Rios Ucayali and Maraiion a further change occurs. Here pods are often definitely pointed and have a very warty surface. They are larger than either the Brazilian or the Ecuadorian pods, the trees are often of immense size for cocoa and the beans are large and plump though still uniformly dark purple in colour. As one leaves the actual river valley and proceeds up the tributaries to the west of the Rio Maranon there is no doubt that the type of cocoa tree is very similar to the semi-wild trees in Ecuador known as amacigales and which are without much doubt the parents of the Cacao Nacional.

At various points in this route local dominant types occur. Near Iquitos a very large balloon pod may be seen which is as smooth as a Calabacillo and which gives large lozenge shaped seeds. On the Rio Nanay around Iquitos the salient type is a delicate kind of Amelonado, long and oval without bottle neck or point. ‘On the Rio Ucayali bottle neck constriction is usually present and on the Maranon the pods are definitely warty and with a pronounced point.

The chain, however, is unbroken between the Brazilian cocoa and the Ecuadorian cocoa, showing that the types are probably the end points of diverging segregation of a central type, probably that of the northern tributaries of the northern Amazon near Iquitos.

I t is still too early to say how accurate this picture is, but fortu- nately there is a great deal of activity going on to collect and describe populations, which will provide a fuller picture.

Trinitario

The Trinitario populations a re considered to belong to the Foras- teros according to Cheesman (1944) and Cuatrecasas (1964),

Criollo, Forastero and Trinitario 33

Map 2.1 Northern South America showing places and rivers mentioned in this chapter. After Pound’s visits the boundary between Ecuador and Peru was altered substantially and many of the places referred to by Pound as being in Ecuador are now in Peru.

although they have features intermediate to Criollo and are descended from an initial cross between Criollo and Forastero, usually Amelonado trees. Trinitarios are not found in the wild state. The first cross gives very vigorous, prolific, hardy trees and these characters continue for a few generations, but in later generations, the vigour declines. However it remains higher than that found in the old Criollo trees. Evidence for this phenomenon has been found in Bioko (Fernando Po) (Swarbrick el al. 1964), in Central America (Soria 1970) and in Indonesia. Trinitario populations are usually variable in pod and bean characters because the parents have highly contrasting characters.

The prime example of a Trinitario population is that which exists in Trinidad, but its origin cannot be fully explained. It is generally agreed that Criollo cocoa was grown in Trinidad until the middle of the eighteenth century, at which time there was a ‘blast’ which practically wiped out the cocoa industry. What happened after that calamity is not known, but in 1825 a cocoa estate manager in Venezuela imported vigorous planting material from Trinidad (Pittier 1935). At that time the plantings of Criollo cocoa along the north coast of Venezuela had become old and in need of replanting. The new planting material from Trinidad became popular in


Venezuela and was referred to as Trinitario. Obviously this material had been planted in Trinidad for some considerable time before 1825 and there are various ways in which it may have arisen. After the ‘blast’ in Trinidad some remnants of the old Criollo plantings may have survived. It is probable that at the same time the Amelonado reported by Myers (1930) in Guyana existed in a wild or semi-cultivated state in the Orinoco estuary of Venezuela. The Trinidad cocoa planters in their search for new planting material may have introduced Amelonado seed which then crossed with the remaining Criollo to form the Trinitario population. Alternatively, a few Criollo plantings may have existed in the Orinoco estuary and the crossing may have taken place there. In either case Trinidad developed its own population which should properly be called ‘Trin- idad Trinitario’. This is the population which was described by Pound (1932) and from which the ICS (Imperial College Selection) clones were selected.

Venezuela developed its own Trinitario population starting with the introductions from Trinidad which must have crossed with the local Criollo trees.

In Ecuador, a Trinitario population arose from the introduction of a few pods from Trinidad about 1890 (Pound 1938). The progeny proved to be vigorous and many planters obtained seed from these trees which became known as Venezelanos. In the 1930s and 1940s planting material was introduced from Venezuela in the hope that it would help to offset the catastrophic effect of witches’ broom disease. The native Cacao Nacional probably contributed to this population of which there are two subtypes: Venezelano morado with red pods and Venezelano verde with green pods (Soria 1970).

In Cameroon developments were different from those in other West African countries, because at the turn of the century the Germans introduced a comprehensive collection of planting material from the main cocoa-growing areas in South America which was planted in the Botanic Garden at Victoria in Cameroon (Preuss 1901). There must have been a high incidence of red podded trees in the collection, from which open-pollinated seed was collected to plant the rapidly developing plantations in West Cameroon, because the older cocoa plantings in Cameroon show a high incidence of trees producing red pods and there is considerable variation’ in pod characters. The population is Trinitario, not West African Amelonado. In East Cameroon this planting material was probably mixed up with introductions by local people from Fernando Po.

Trinitario in South-East Asia and Oceania Some of the material in the Botanic Garden at Victoria was transferred to the Pacific island of Samoa. These introductions and others from Sri Lanka and Java were subsequently moved to Papua New

Criollo, Forastero and Triniiario 35 Guinea. Cocoa plantings in these countries, and in other places like the Fiji Islands, consist mainly of a variable Trinitario population, partly red podded.

Exceptional cases

There are a few types which do not fit obviously into any of the populations described, as shown by the following examples:

1. In Brazil there exists a population known as Catongo which was selected for white beans, and propagated deliberately by seed. On the basis of seed colour alone it would classify as a Criollo, but the pod husk is hard, the pod is an Amelonado and the average number of beans per pod is more than thirty-five. The parent tree was originally found in an Amelonado population and is considered to be a mutant. Therefore, Catongo belongs to the Forastero type and the population could be described as a ‘white- beaned Amelonado’.

2. In Indonesia about 10,000 ha of budded, clonal cocoa have been planted. The clones are named Djati Roenggo (DR) after the plantation in Central Java where they were selected. The pod colour is red or green, the beans have white cotyledons and the pod husk is apparently soft, all Criollo characters; the number of beans per pod however is thirty-five, a Forastero or Trinitario character. These few clones do not represent the original population which became extinct before 1940. The history of these selections gives a clue as to their proper classification (van Hall 1914). Around the turn of the century the management of Djati Roenggo plantation introduced one cocoa seedling from Vene- zuela that was expected to be of the Venezuelan Criollo type, famous at the time for its superior quality. When the tree started bearing, it was obvious from the pod type and the purple beans that it was a Venezuelan Trinitario which caused great disap- pointment. Nevertheless a small field was planted with open- pollinated progeny; growth was very vigorous by the standard of those days and eventually a number of trees with many white beans were identified amongst the progeny. The DR clones orig- inate from selections from this population and are therefore white bean segregants from a Trinitario population and should be classified as Indonesian Trinitario.

Centres of diversity

The primary centre of diversity is generally accepted to be the upper Amazon basin where a considerable and useful variation has been recorded by direct observation on trees and from research on


material introduced from this area. Apart from variation in the morphological characters of the pods and beans, resistance, and in some cases increased susceptibility, to witches’ broom disease, Phy- tophthora pod rot, canker, and cocoa swollen shoot virus has been found. Good vigour is generally encountered but even crosses between populations collected in places not far apart have shown hybrid vigour.

The tropical part of Central America qualifies as a secondary centre of diversity on account of the differences between and the variation within the Criollo populations. However spectacular, the variation seems limited to pod characters only and vigour appears to be generally lacking.

Conclusion As mentioned earlier there is at the time of writing considerable activity in the Amazon basin studying cocoa populations and collecting genetic material which may prove useful in breeding programmes. This activity is of great importance partly because the Amazon forests are being felled at an alarming rate so that the gene pool is liable to be reduced or even destroyed altogether. In addition there is a vital need for new genetic material to be collected, assessed and made available to plant breeders.

References Anon (1981) Genetic resources of cocoa. International Board for Plant Genetic

Resources. Rome. Alvim, P. de T. (1977) Cacao. In P. de T. Alvim and T. T. Koslowski (eds) Ecophy-

siology of Tropical Crops. Academic Press: New York, pp. 279-313 Beek, M. A., Eskes, A. B. and Toxopeus, H. (1977) Some factors affecting the fat

content in cacao beans (Theobroma cacao L.) with emphasis on the effect of the pollinator parent. Turrialba 27, 4: 327-32.

Cheesman, E. E. (1944) Notes on the nomenclature, classification and possible relationships of cocoa populations. Trop. Agric., Trin. 27: 144-59. Reprinted 1982 in Arch. Cocoa Res. 1: 98-116.

Cope, F. W. (1962) The mechanism of pollen incompatibility in Theobroma cacao L. Heredity 17: 157-82.

Cuatrecasas, J. (1964) Cacao and its allies. A taxonomic revision of the genus Theo- broma. Contrib. U. S . Nat. Herb. 35, 6: 379-614.

Kaufmann, 1. (1975) Ecology and behaviour of cocoa pollinating Ceratopogonidae in Ghana, W. Africa. Environ. Ent. 4: 347-51.

Knight, R. and Rogers, H. H. (1955) Incompatibility in Theobroma cacao. Heredity

Knoke, J. K., Soria, S. de J. and Chapman, R. K. (1980) Cacao pollination with spray equipment in Costa Rica. Rev. Theobroma 10: 213-24.

Lucas, P. and Decazy, B. (1981) Influence des traitements insecticides contre les mirides du cacaoyer sur les conditions de pollinisation. Cafe Cacao The 25: 29-36.

McCreary, C. W. R. , McDonald, J. A., Muldoon, V. I. and Hardy, F. (1943) The root system of cacao. Trop. Agric., Trin. 20: 207-20.

9: 69-77.

References 37

McKelvie, A. D. (1956) Cherelle wilt of cacao. I Pod development and its relation

Myers. J G. (1930) Notes on wild cacao in Surinam and in British Guiana. Kew Bull.

Myers, J . G . (1934) Observations on wild cacao and wild bananas in British Guiana.

Pittier, H. (1935) Degeneration of cacao through natural hybridisation. J . Hered.

Posnette, A. F. (1950) The pollination of cacao in the Gold Coast. J . Hort. Sc i .

Posnette, A. F. and Entwistle, H. M. (1958) The pollination of cocoa Rowers. Rep. Cocoa Conf., London 1957 66-8.

Pound, F. J . (1932) The genetic constitution of the cacao crop. First Ann. Rep. Cacao Res. lY31, Trinidad: 10-24.

Pound, F. J. (1938) Cacao and Witchbroom Disease of South America. Port-of-Spain, Trinidad. Reprinted 1982 in Arch. Cocoa Res. 1: 20-72.

Pound, F. J . (1945) A note on the cocoa population of South America. Rep. and Proc. Cocoa Res. Conf., London. 1945. Colonial 192: 95-7. Reprinted 1982 in Arch. Cocoa Res. 1: 93-7.

Preuss, P. (1901) Expedition nach Central. und Sudamerika. Verlag des Kolonial- Wirtschaftlichen Kornitees, Berlin.

Soria, J. de V. (1970) Principal varieties of cocoa cultivated in Tropical America. Cocoa Growers' Bull. 15: 12-21.

Soria, J. de V. and Enriquez, G. A . (eds) (1981) lnternafional Cacao Culfivar Cata- logue. Tech. Bull. 6, Trop. Agric. Res. and Training Centre, Turrialba.

Soria, S. de J., Garcia, J. R . and Trevizan, S. (1980) Mechanical pollination of cacao using motorised knapsack sprayers in Brazil, agro-economical assessment. Rev. Theobroma 10: 149-55.

Stahel. G. (1920) Een wild cacaobosch aan de Marnaboen Kreek. De Indische Mercuur 43e Jaarg. no. 39: 68 1-2.

Swarbrick, J. T., Toxopeus, H. and Hislop, E. C. (1964) Estate cocoa in Fernando Po. World Crops 16, 2: 35-40.

Thrower, L. B. (1960) Observations on the diseases of cacao pods in Papua New Guinea: I1 - Cherelle wilt. Trop. Agric., Trin. 37, 121-4.

Toxopeus, H. and Jacob, V. J. (1970) Studies on pod and bean values of Theobroma cacao L. in Nigeria: 11. Number of beans per pod, with special reference to the natural pollination process. Neth. J . Agric. Sci. 18: 188-94.

Toxopeus, H. and Wessel, M. (1970) Studies on pod and bean values of Theobroma cacao L. in Nigeria: I. Environmental effects on West African Amelonado with particular attention to annual rainfall distribution. Neth. J . Agric. Sci. 18: 132-9.

to wilt. J . Exp. Bot. 7: 252-63.

1930, 1-10

Trop Agric., Trin. 11: 263-7.

26: 385-90.

25: 155-63.

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Congo Belge et du Ruanda-Urundi 50, 6: 1541-600. Voelcker, 0. J. (1940) The degree of cross-pollination in cacao in Nigeria. Trop.

Agric., Trin. 17: 184-96. Wellensiek, S. J . (1932) The genetics of cotyledon colour of cacao as basis for quality

selection. Archief voor de kofiecultuur 5: 217-33. Winder, J. A . (1977) Recent research on insect pollination of cocoa. Cocoa Growers'

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logical studits in Theobroma cacao L. Philippine Agriculturist 43: 613-36.

Chapter 3

Environment G. A . R. Wood

The major components of the environment of a cocoa farm are the climate and the soil and there is a close relationship between the two aspects. They are’, therefore, discussed together in this chapter.

Climate

Before dealing with the individual factors of climate - rainfall, temperature, sunshine and so on - the climates of the major cocoa growing countries will be described. They are illustrated in Figs 3.1-10 and summarised in Table 3.1.

South America At the primary centre of diversity of Theobroma cacao, in the headwaters of the river Amazon. the annual rainfall is more than

Table 3.1

Country, place Annual Dry Temperature (“C) Sunshine

Summary of climatic hata

rainfall months* (mm) Mean max. Mean min. (h )

Brazil, Itabuna Ecuador, Pichilingue Cameroon, Yaoundt Ghana, Tafo Ivory Coast, Gagnoa Nigeria, Ondo Malaysia, Perak Sabah, Tawau Papua New Guinea, Keravat

1,720 2,046 1,711 1,600 1,326 1,634 1,763 2,098 2,792

1 26-30.5 7 28-31 3 26.0-30.5 4 27.5-32.5 4 28-33 4 26-32 0 31.5-33 0 30.5-32 0 29.5-31.5

17-21 20-22.5

18.5-19.5 20-21.5 21-22

20.5-22 22.5-23.5

21-22.5 20.5-22

1,980 872

1,639 1,914 1,868 1,918 2,336 1,829 2.034

* Dry months - number of consecutive months with < 100 mm rainfall

Climate 39

2,000 mm and fairly uniformly distributed. Temperatures vary between 20 and 3WC, but for trees in the lower storey of the rain forest the diurnal variation is reduced to about 6°C. Similarly, air movement is almost non-existent near the ground and the amount of light which penetrates the forest canopy is very small. Wild cocoa trees are often found alongside rivers growing on alluvial soils, situ- ations which are both well watered and well drained.

Brazil In the State of Bahia where over 90 per cent of Brazil's cocoa is grown, the cocoa area is restricted to those parts which receive adequate rainfall. On the coast the annual rainfall is 2,000 mm but it falls off to the west and at the western limit, which is less than 100 km from the coast, annual rainfall is about 1,150 mm. The dry season is not as distinct as in West Africa and monthly rainfall in the cocoa zone rarely falls below 60 mm. Monthly mean temperatures vary considerably as might be expected at 15" from the Equator and are on average rather lower than temperatures in West Africa (Fig. 3.1).

Cocoa is now being planted in the Amazon basin and the data for the new area in the State of RondBnia (Fig. 3.2) are based on only four years' records, but they show a much more seasonal rainfall pattern with three consecutive dry months. The temperature pattern is also different, there being less variation in maximum temperature. These differences between RondBnia and Bahia are likely to be reflected in different growth and cropping patterns.

Ecuador The data for Ecuador in Table 3.1 and Fig. 3.3 are in marked contrast to the other countries. The rainfall which amounts to 2,000 mm falls in just over five months, December to early May, while the rest of the year is dry. Furthermore, temperatures are lower in the dry season than in the wet and this is because the weather is sunny during the wet season but overcast and dull during the dry season. Therefore sunshine hours are higher in the wet season than in the dry and the annual total is less than half the figures for West Africa and Bahia. The low cloud and drizzle or 'garua' which occurs in the dry season maintains a high humidity as well as lowering the temperature. This unusual climate is due to the annual variation of the cold Humboldt current.

West Africa The climate in all the cocoa-growing areas of West Africa follows a similar cycle with a few exceptions. The figures illustrating the climates of Cameroon, Ghana, Ivory Coast, and Nigeria (Figs 3.4-7

40 Environment

I Average of 16 years : 1965-80.

Total for year : 1,720 mm

J F M A M J J A S O N D

Brazil: CEPEC, Itabuna 14" 45' S 39" 14' W. SOURCE: CEPEC (1981). Fig. 3.1

Climate 41

30- F Mean

2 v

u

25-

E b

0

20 -Mean

0 0

max

0 .

min

Average for 4 years : 1914-77

0

J F M A M J J A S O N D

Fig. 3.2 Brazil: Ouro Preto, RondBnia 10" 50' S 62" 30' W. SOURCE: CEPEC (1981).

42 Environment

Total for year : 872 h Averages for:

23 years

In

0 0

0

Mean max

0 . .

Mean min

9 years

Total for year : 2.046 mm

8 years

A M J J A S O N D

Fig. 3.3 Ecuador: Pichilingue 1" 06 ' s 79" 29' W. SOURCE: W. Hadfield (pers. comm.).

Climate 43

Average for 10 years

0

0

Mean miix

1 J F - M

0 0

0 . = . . . a

Total f o r year : 1.711 m m

0

M J J A s o N 7

D

Fig. 3.4 Cameroon: Yaounde 3" 50' N 11" 35' E. SOURCE: Direction de la Meteorolo-

44 Environment

Total for year : 1.914 h

I h

9 25

c

x a

aJ c . -

3 m

Average for :

33 years

S -

. * . 0 0 .

-Mean max 0

b

0 b

b

38 years -

0 . ' 0

. . * . . - a

Mean min

Total for year : 1,599 mm I

38 years

Fig. 3.5 Ghana: Tafo 6" 15' N 0" 22' W. SOURCE: Ann. Rep. Cocoa Res. Insf. Ghana I975 - 76.

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