D. H. URQUHART
Formerly Director of Agriculture
in the Gold Coast
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First published z955
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PRINTED IN GREAT BRITAIN
BY WESTERN PRINTING SERVICES LTD., BRISTOL
Sir Geoffrey Clay, K.C.M.G., O.B.E., M.C., B.Sc., N.D.A., N.D.D.
Agricultural Adviser to the Secretary of State for the Colonies
COCOA may justly be termed one of the world's most favoured crops,
favoured because, while the consumption of cocoa and chocolate is
expanding with the rising standards of living, the cocoa tree is dis-
tinctly selective as to soil and climate and is particularly susceptible
to certain pests and diseases. It is, therefore, no easy matter for the
world's cocoa production to be expanded by the opening up of new
areas of production and existing producers appear to be favourably
shielded at present, and for many years to come, from that fear of
primary producers of any major staple commodity that production
will exceed consumption.
Because of the selectivenature of the cocoa tree attempts to establish
new areas must be backed by the fullest knowledge of its optimum
environment, the systems of cultivation which by experience and
scientific investigation have been established in the various cocoa
growing areas of the world either by peasant smallholders or on large
estates, the diseases and pests to which the plant is subject and the
research which is being conducted on the crop.
In recent years, the conferences in London organised by the Cocoa,
Chocolate and Confectionery Alliance have provided a valuable
forum for the exchange of views and experiences between research
workers in cocoa, and between producer representatives and the cocoa
and chocolate manufacturers from all over the world. The reports
of these conferences contain much practical as well as scientific in-
formation, but so far as I know no attempt has yet been made to
bring together all the existing information into one book.
It is against this background that I welcome the timely publication
of this book on Cocoa as second in the series of books on Tropical
Agriculture which are being published with the active encouragement
of the Colonial Advisory Council of Agriculture, Animal Health and
Forestry. Whilst essentially intended by its author as a practical
handbook for cocoa planters, the book will be of undoubted value
in any institution concerned with the teaching of tropical agriculture,
In its author, Mr. D. H. Urquhart, we have a man with, I suppose,
the widest experience of cocoa growing in the world to-day. Mr.
Urquhart spent nearly a quarter of a century in the Colonial Agri-
cultural Service in Nigeria and in the Gold Coast, which together
produce a high proportion of the world's cocoa crop. For several
years prior to his retirement he occupied the post of Director of
Agriculture in the Gold Coast; his appointment to this important
post came at a time when drastic action was needed to deal with the
catastrophic spread of the swollen shoot virus disease of cocoa which
has caused such heavy losses to cocoa growers in West Africa. Mr.
Urquhart is, therefore, well qualified from his experience to advise
on the development of cocoa production by peasant farmers and the
organisation of services to such farmers. In addition, since his
retirement in 1950, Mr. Urquhart has, at the instigation of and
financed by Messrs. Cadbury Brothers Limited, carried out many
missions to existing and potential cocoa growing areas of the world
and has thus had a unique opportunity of studying at first hand the
conditions and problems present in most of them.
I am sure that the book will receive a most favourable reception
from all those, both planters and governments, concerned with cocoa
development, and that its value will be reflected in the improvement
and expansion of cocoa production throughout the tropical world.
Colonial Office, G. F. CLAY
Great Smith Street,
This volume is one of a series of books on tropical agriculture
which are being published with the active encouragement of the
Colonial Advisory Council of Agriculture, Animal Health and
Forestry, under the editorship of Sir Harold Tempany, C.M.G.,
C.B.E., D.Sc., F.R.I.C., formerly Agricultural Adviser to the Secre-
tary of State for the Colonies and previously Director of Agriculture
in Mauritius and Malaya.
Rice, by D. H. Grist.
Other volumes in preparation:
Introduction to Tropical Agriculture, by Sir Harold Tempany.
Tea, by T. Eden.
I AM indebted to people in various countries for generous help and
my thanks are due to them for providing valuable information for
In Britain I am chiefly indebted to the firm of Cadburys for
giving me every facility to write the book, and I have been greatly
assisted not only by the encouragement of their Board, but by
much technical advice and help from my Bournville colleagues. They
have read the drafts of appropriate sections and corrected the proofs,
and during my absences abroad have watched over the preparation
of the material on my behalf. I would list the following to whom I
am especially indebted: Mr. John Cadbury, Mr. W. E. Cossons,
Mr. Spencer L. Hale, Mr. W. McL. Hood, C.B.E., Dr. G. R. Howat,
Mr. F. T. Lockwood, Miss D. M. Stevens, Mr. R. V. Wadsworth,
and Mr. G. A. Ross Wood. I have had valuable advice from Mr.
D. L. Martin, a director of Unilever, who is responsible for guiding
the immense plantation interests of that company. I have had the
advantage of consultations with Dr. A. F. Posnette, whose outstand-
ing work in research in cocoa is well known.
The value of the book is greatly enhanced by the inclusion of the
chapter on Virus Diseases by Dr. A. F. Posnette, East Malling
Research Station, and the chapters on Rehabilitation, Botany, and
Soils, respectively by Professor C. Y. Shephard, C.B.E., Professor
R. E. Baker, and Professor F. Hardy, C.B.E., all of the Imperial
College of Tropical Agriculture, Trinidad.
The subject matter of the chapter on Vegetative Propagation of
Cocoa by Rooted Cuttings, etc., is based mainly on the work of Dr.
Harry Evans in Trinidad, supplemented by some of his unpublished
writing and information provided by his successor, Mr. Dennis
Murray. Mr. Moll, of the Trinidad Cocoa Board, supplied informa-
tion on large-scale production of cuttings.
Much of the information included in the chapters on The Cocoa
Plantation is derived from discussions with experienced planters in
Trinidad, particularly Mr. Carl de Verteuil and Mr. Neal Fahey, who
generously placed at my disposal knowledge gained from many years
of practical work.
In the Gold Coast, I received help from members of the Depart-
ment of Agriculture, notably Mr. James D. Broatch, Deputy
Director; Mr. P. S. Hammond, M.B.E., Assistant Director; Mr.
John Paine, formerly of the Department, and Mr. Victor Osei, all of
whom are authorities on cocoa culture in West Africa.
I am grateful to Sir Harold Tempany, C.M.G., C.B.E., for ready
help and guidance.
Finally, I acknowledge the assistance of my wife who helped me
in the work throughout.
The author takes responsibility for views expressed in the book.
LIST OF PLATES XV
The Origin of Cocoa-Development of New
Sources of Supply of Cocoa-Developments
in Cocoa Consumption-Expansion of the
Production of Cocoa The Prospects for
II. THE BOTANY OF COCOA 6
History of Cocoa Planting-Natural Habitat
-Habit of Growth-Types of Branches-
The Leaves-The Flowers-Pollination-The
Fruit-Cocoa Varieties-Nomenclature of
III. CLIMATE 17
Rainfall- Temperature and Humidity -
IV. COCOA SOILs 23
Root-room Sands Clay-loams Soil-
aggregate Cementing Agents-Soil-crumb-
Forest Soils-Soil Depth-Classifying Soils
on a Root-room Basis-Planting Distance-
Effects of Forest-felling-Functions of Shade
-Soil Erosion-Rehabilitation of Worn-out
Cocoa Lands-Mulching and Mulches-
Effects of Mulching: Use of Fertilizers-
V. THE COCOA PLANTATION (1) 36
ESTABLISHMENT AND MAINTENANCE
I. Preliminary Preparation
Overall Considerations-Choice of Site-
Soil Assessment-Communications, Water
Supply, etc.-Planting Material-Preliminary
II. Preparation of the Land
Clearing: Complete Felling and Burning;
Selective Thinning; Partial Clearing-Sale of
Timber-Sequence of Operations-Mechani-
zation in Felling-Planting in old Plantation
Land or Land without Forest-Prevention of
The Site, Shading and Shelter-Planting
Seed-Baskets-Cocoa in Seed Beds-Supply
and Treatment of Nursery Plants-Nursery for
Shade Trees-Nursery for Rooted Cuttings
IV. Preparation for Planting
Spacing: Close v. Wide-Optimum spacing;
Close Spacing; Thinning; Practice in Dif-
ferent Countries; Spacing of Shade Trees-
Lining: Lining before General Felling;
Lining Methods; Lining on the Contour-
Holing: Treatment of the Soil; Experience
in the Gold Coast
VI. THE COCOA PLANTATION (2) 52
VEGETATIVE PROPAGATION OF COCOA BY ROOTED
CUTTINGS, WITH NOTES ON SOME OTHER METHODS
History of the Development of Rooted Cocoa
Cuttings-The Nursery-Collecting Cuttings
Preparing the Cuttings Propagators -
Preparation of Rooting-bin-Striking, or first
stage in producing Roots on the Cuttings-
Conditions inside the Propagator-Harden-
ing-Rooting in Open Beds under Mist
Spray-Use of Greenhouses and Humidifiers
-Storage of Potted Plants-Review of Pro-
pagation Methods-Labour Requirements-
Other Methods of Propagation
VII. THE COCOA PLANTATION (3) 70
PLANTING AND AFTER-CARE
I. Planting in the Field
Planting at Stake-Planting from Nursery
Beds-Planting with Baskets
II. Provision of Shade
Temporary Lateral Shade and Ground
Cover-Lateral Shade-Ground Cover-Per-
manent Overhead Shade-Functions of Shade
-Practice in Different Countries-Methods
of Providing Shade-Type of Shade Tree
Required-Shade Indicators-Control and
Replacement-Impossibility of laying down
Necessity for Protection from Wind-Best
Type of Windbreak-West Indian Practice
Attention required in Early Stages-Later
Stages-Pest and Disease Control-Shaping
and Pruning Removal of Chupons -
Shaping in Relation to Spacing, etc.-
Rooted Cuttings Use of Chupons -
VIII. THE COCOA PLANTATION (4) 85
PREPARATION OF THE CROP FOR MARKET
Precautions to be observed-Labour required
General Observations-Purple Beans-The
Fermenting Process-Observing Progress-
Causes of Unsuccessful Fermentation -
Equipment: Cleanliness-Fermentation of
Different Types of Cocoa-Handling Small
III. Drying and Storage
Sun-drying-Artificial Drying-Cocoa dry-
ing on Lukolela Estates-Types of Driers-
Slow Drying-Testing for Dryness-Storage
IX. PEASANT COCOA CULTURE IN WEST AFRICA 97
History-Methods of Farming and Planting
Labour Required Shade Harvesting,
Fermenting, Drying-Diseases and Pests-
Pros and Cons of Peasant Culture-Improving
Peasant Culture-Some Problems of Replant-
ing and Rehabilitation-The Place of Cocoa
in a Peasant Economy-The Future of the
X. REHABILITATION OF COCOA PLANTATIONS IN TRINIDAD 107
Historical-Defects of the Cultural System-
The Aim of Rehabilitation-Sequence of
Operations-Rehabilitation: Second Phase
XI. PESTS AND DISEASES 120
Methods of Control-Pests: Capsids-Cap-
sids in West Africa-Capsids in Other
Countries Thrips Insects which attack
Leaves and Shoots-Insects which attack
the Main Stem Insects which attack
Pods Termites Birds and Mammals -
Diseases: Black Pod-Witches' Broom-Re-
sistant Trees-Monilia-Mealy Pod-An-
thracnose Botryodiplodia theobromae -
Black Spot and Bark Rot-Pink Disease-
Thread Blights-Red Rust (Algal disease)-
Root Disease-Epiphytes and Parasitic Plants
XII. VIRus DISEASES OF COCOA 145
The Viruses in West Africa: Symptoms-
Rate of Spread-The Vectors-Virus-Vector
Measures: Roguing Trials-Parasites and
Predators-The Selection of Resistant Types
-The Viruses in Trinidad: Symptoms-Rate
of Spread-The Vectors-Control Measures
XIII. COCOA GRADES AND GRADING 156
Types of Cocoa required by Manufacturers-
Preparation and Quality-Defective Beans in
relation to Grading-Standards set by some
Importing Countries-Export Regulations in
of Shell to Whole Bean
XIV. RESEARCH 164
The Historical Background-The Cocoa
Research Conference of 1945-Research at
the Imperial College of Tropical Agriculture
-Research at the West African Cocoa
Research Institute Research in Other
Parts of the World-Results of Research
-Application of the Results of Research
XV. WORLD PRODUCTION AND CONSUMPTION 171
A Factor Restricting Consumption-Impor-
tance of Price in World Markets-Price Fluc-
tuations and their Effect-Marketing in the
Gold Coast and Nigeria-Growth of World
Production-The Rise in Production in West
Africa and Brazil-Limitations to Expansion
in West Africa-Distribution of World Pro-
duction-Effects of Prices on Planting-New
Growing Areas-Effect of Improved Cultural
Methods-Cocoa Products-Local Process-
ing-World Consumption-Consumption in
U.S.A.-Consumption in U.K.-Consump-
APPENDIX I 189
APPENDIX II 191
Costs of Cocoa Culture on Estates and Peasant
APPENDIX III 202
Plants per Acre at Different Spacings
APPENDIX IV 203
Preparation of Rooted Cuttings
APPENDIX V 205
APPENDIX VI 211
Preparation of Bordeaux Mixture
APPENDIX VII 212
Cocoa Price Equivalents
APPENDIX VIII 213
Glossary of Terms
Between pages 48-49
I. Healthy cocoa tree in bearing.
II. Types of cocoa pods.
III. Vegetative propagation: Stem-cutting.
IV. Vegetative propagation: Stem-cutting.
V. Temporary shade for young cocoa.
VI. Young cocoa plantation.
VII. Effect of shade.
VIII. Drying cocoa.
IX. Sections of cocoa beans after preparation for the market.
X. Cocoa growing under forest shade in the Gold Coast.
IN BLACK AND WHITE
Between pages 8-9
1. A cocoa farm in the Gold Coast.
2. A chupon branch of a cocoa tree with leaves in a i-spiral giving
rise to a jorquette of five fan-branches.
3. Cocoa flower.
4. A fan-branch.
5. A collection of cocoa pods.
6. A chupon arising from the base of a mature tree.
7. A cocoa tree about seven years old grown from a fan-cutting.
8. A chupon arising from a fan-cutting.
Between pages 40-41
9. Clearing jungle in Malaya for cocoa planting.
10. An old cocoa field cleared and lined for re-planting.
11. Clearing secondary forest in the Gold Coast for cocoa planting.
12. A heavy-bearing cocoa tree on a plantation in Brazil.
13. Seedlings growing in baskets.
14. A tree grown from a rooted cutting on an estate in Trinidad.
15. A seedling nursery at a Department of Agriculture station in the
Between pages 56-57
16. Nursery trees under Gliricidia shade, Trinidad.
17. The equipment used in preparing stem-cuttings. *
18. Stem- and single-leaf cuttings trimmed and prepared for the
19. Propagating-bins under construction.
20. A battery of rooting-bins.
21. Watering the cuttings by means of a perforated pipe installed
inside the bin.
22. Effect of moisture conditions on rooting.
23. Effect on leaves of abnormal conditions in rooting-bin.
24. Potting rooted cuttings.
25. Rooted cuttings with their first flush.
26. Storage space for rooted cuttings.
27. Storage space; the cuttings shaded with camouflage netting.
28. Open spray bed with lines of T-jets on both sides.
Facing page 64
29. A small greenhouse for hardening rooted cuttings using a
Facing page 65
30. Bench grafting.
Between pages 80-81
32. Young cocoa established under forest trees which have been
selectively thinned, Belgian Congo.
33. Young cocoa growing in the shade of bananas, Grenada.
34. A mixed plantation of coconuts and cocoa in New Guinea.
35. A cocoa plantation in Western Samoa with ground cover of
Dadap (Erythrina lithosperma).
36. Windbreaks on River Estate, Trinidad.
37. Cocoa trees growing beneath shade of the Umbrella tree in the
38. Young cocoa growing in partly thinned jungle, Malaya.
39. Young cocoa trees growing under thinned forest shade in the
40. A young cocoa plantation at Keravat, New Britain. Shade trees
are Leucaena glauca.
Between pages 96-97
41. Cocoa harvest in West Africa.
42. Building a fermenting heap in West Africa.
43. Covering a completed heap with plantain leaves.
44. Cocoa drying on mats in the Gold Coast.
45. A fermentary, Venezuela.
46. The inside of the fermenting-house shown in Fig. 48.
47. A typical fermenting-box, Grenada.
48. A fermenting-house in the Belgian Congo.
49. Drying-sheds on an estate in Trinidad.
50. Trays outside drying-house at Lukolela, Belgian Congo.
Between pages 112-113
51. Cocoa growing under shade of mixed forest trees in the Gold
52. Exploitation of forest land.
53. A farmer's nursery beside a small stream.
54. A farmer among his young cocoa trees, Western Province, Gold
55. A farmer unrolling his drying mats in the morning.
56. Young clonal trees planted in gaps in a cocoa field to replace
missing trees or poor bearers.
57. Rehabilitation after swollen shoot.
58. Seedling nurseries in the Gold Coast.
59. Cocoa nurseries in the Gold Coast.
Between pages 128-129
60. Young cocoa trees heavily damaged by capsids.
61. A young cocoa tree which has been severely damaged by capsids.
62. Capsids on a young green stem.
63. Capsid attack on cocoa pods. Damage due to Sahlbergella
64. Capsid attack on cocoa pods. Damage due to Helopeltis.
65. Stems damaged by capsids.
66. A branch from a cocoa tree which has been attacked by capsids
and subsequently invaded by a fungus.
67. Control of capsids, Gold Coast. A young tree being painted with
68. Control of capsids, Belgian Congo. A hand-operated machine
-Le Mistral-which is used for dusting cocoa.
Between pages 144-145
69. Cocoa pods affected by black pod.
70. A cocoa tree bearing several black pods.
71. Thread blight.
72. Cocoa pods suffering from Monilia disease.
73. Witches' broom disease. A lateral fan broom.
74. Witches' broom disease. An indurated pod.
75. Cocoa trees dying of swollen shoot virus.
Between pages 152-153
76. Leaf symptoms of swollen shoot.
77. Mealybug tents on a cocoa stem.
78. Adults and nymphs of the mealybug, Pseudococcus njalensis.
79. A large tented colony of mealybugs on a cocoa pod.
80. Mature silk cotton or kapok tree (Ceiba pentandra) about 150
81. Typical swellings produced by swollen shoot virus.
82. A broken canopy caused by an outbreak of swollen shoot.
83. A diseased cocoa tree being cut out.
84. A small outbreak of swollen shoot after cutting out.
Facing page 160
85. A stab sampler being used to withdraw beans from sealed bags.
86. A sample of beans being cut for grading at a buying station in
the Gold Coast.
87. Samples of cocoa being graded before shipment at Accra.
Facing page 161
88. Typical samples of beans, British West Africa.
89. Typical samples of beans, Trinidad.
90. Stored cocoa showing external and internal signs of damage by
Between pages 168-169
91. Imperial College of Tropical Agriculture, Trinidad.
92. Cocoa fields in Grenada.
93. West African Cacao Research Institute, Tafo, Gold Coast.
94. Cocoa awaiting shipment on the beach at Winneba, Gold Coast.
95. Surf boats loaded with cocoa leaving the beach at Accra, Gold
96. A lorry loaded with cocoa on its way from a Gold Coast buying
station to rail-head.
97. Cocoa being loaded into lighters prior to shipment at Takoradi,
ACKNOWLEDGEMENTS OF ILLUSTRATIONS
The author gratefully acknowledges permission to reproduce
photographs, as follows:
Gold Coast Information Services, Nos. 41-43, 55, 59, 61-67, 77,
81-83, 87, 93, 95-97.
Mr. D. A. Donald, Senior Agricultural Officer, British Solomon
Islands, No. 35.
Imperial College of Tropical Agriculture, Nos. 22a, b, c, 23a, b,
Mr. J. Nicol, Entomologist, West African Cacao Research Insti-
tute, Nos. 3 (from the Journal of Horticultural Science), 60, 69, 76a,
b, c, d, e, 78, 79, 80.
Senor Manuel Palma (per Mr. Tresper Clarke, of Rockwood &
Co., New York), No. 45.
Mr. Paul Holliday and H.M.S.O., Nos. 73 and 74.
Nos. III and IV were drawn by Mrs. C. S. Watts (I.C.T.A.); No.
IX is by Bournville Works Studios.
The others are from photographs by the author and Mr. G. A. R.
All photographs not otherwise acknowledged are by the author
and Mr. Wood, and No. 85 is by Mr. P. B. Redmayne; they are
reproduced by permission of Cadbury Brothers Ltd.
DIAGRAMS AND CHARTS:
Fig 1 is adapted from Le Cacaoyer i Tafo, Gold Coast, by L.
Poncin (Brussels, 1950); Fig. 2 is from a paper by Mr. C. F. Charter,
(Cocoa Conference Report, 1949); Fig. 3 is based on a drawing sup-
plied by the Cocoa Board, Trinidad, and Fig. 4 on drawings supplied
by New Zealand Reparation Estates; Figs. 5 and 6 are by Mr. J.
Nicol and have been reproduced in Insect Pests in Cacao Trees; Fig.
7 has previously appeared in the Trinidad Board of Agriculture
Bulletin No. 1 by Mr. R. L. Guppy; Fig. 8 is by Dr. A. F. Posnette
and has appeared in The Annals of Applied Biology; Figs. 9-16 are
from Cocoa-A Crop with a Future, by Mr. Paul Bareau (Cadbury
Brothers, Ltd.); Fig. 19 is reprinted from Nature.
Information as to previous publications may not be complete, but
the above list is believed to be accurate.
The Origin of Cocoa-Development of New Sources of
Supply of Cocoa-Developments in Cocoa Consumption-
Expansion of the Production of Cocoa-The Prospects for
THE ORIGIN OF COCOA*
OCOA and chocolate are derived from the seeds of Theobroma cacao,
a small tree indigenous to the forests of Central and South America.
The existence of cocoa as a cultivated crop dates back to the re-
mote past in that region; the Maya Indians of Central America had
an intimate knowledge of cocoa cultivation long before the Spanish
conquest in A.D. 1519. In his letters to Charles V, the reigning
Spanish monarch, Cortes, the Spanish conqueror of Mexico, refers
to cocoa cultivation and the use of the product as an article of diet
by the Mayas and Aztecs.
It is recorded that the Maya Indians used to make a drink from
the seeds of cocoa by pounding them with maize and boiling the
mixture with capsicum in water. The Spaniards, apparently, did not
like this decoction and devised a method of mixing the powdered
beans with sugar and brewing a drink which was more to their taste.
They introduced this mode of consuming cocoa, with the product
itself, into Spain. At first exports to Spain consisted of the beans
mixed with sugar and spices, but later the beans were exported in
their natural state.
It was not, however, until the end of the sixteenth century that a
taste for cocoa became firmly established in the Old World. About
that time cocoa is first mentioned in shipping documents and it had
become a not unimportant item of commerce.
In the early years exports came only from Central America and
were exclusively confined to Spain, owing to the policy of the
Spaniards of restricting trade with the Americas solely to exports to
that country. Later, however, exports of cocoa began to come from
Venezuela. This was the result of the intervention of the Dutch,
The spelling COCOA is used throughout the book, except where the botanical
form CACAO is quoted, e.g. in the authorities mentioned in Chapters II and V.
who had established themselves on the island of Curacao off the
Venezuelan coast and commenced the export of Venezuelan cocoa
From being originally confined to Spain, cocoa drinking had, by
the early seventeenth century, spread among all the great nations of
Europe. The trade in cocoa had by then fallen largely into Dutch
hands although the countries of production were controlled by Spain.
Cocoa consumption was in those days confined to the form of
drinking chocolate, and was restricted to the wealthier sections of
the community, by reason of its high price. Chocolate drinking was
very popular at many European courts, e.g. at the courts of Charles
II in England and Louis XIV in France.
DEVELOPMENT OF NEW SOURCES OF SUPPLY OF COCOA
The increasing popularity of cocoa caused the tree to be introduced
into various other tropical countries. The Spaniards are reported to
have introduced it into Trinidad in A.D. 1525; there are legends that
the tree is indigenous to that island, but this is doubted. It spread
subsequently to most of the other West Indian islands where condi-
tions are suitable. The Spaniards are also reported to have introduced
cocoa into the Philippines in A.D. 1670, while they are also alleged
to have introduced it into Celebes as early as A.D. 1580. Its spread
through what is now Indonesia was, however, probably due to the
Dutch, who are also credited with having introduced it into Ceylon,
although there is no record of the exact date.
It is probable that the Dutch also introduced cocoa into Sao
Tom6, an island in the Gulf of Guinea, which was occupied by
them from 1641 to 1844, when it reverted to the original discoverers,
the Portuguese. Historically, this is of importance because it was
from Sao Tom6 that cocoa was said to have been introduced into
West Africa in the latter part of the nineteenth century.
Cocoa production extended during the seventeenth century
throughout the West Indian islands and began to gain ground in
overseas markets, but the industry suffered a severe setback in 1727
when a hurricane destroyed many plantations.
Cocoa production in South America was for long confined to
Venezuela, owing to restrictions imposed by Spain; it was only when
the Spanish grip began to slacken at the end of the eighteenth century
that developments began to occur in other South American countries.
The first country to develop an export trade after Venezuela was
Ecuador. Further developments were delayed by the South American
wars of liberation but subsequently developments proceeded fairly
Expansion of the Production of Cocoa 3
rapidly, and exports appeared from Colombia, Peru, Bolivia and the
From Brazil, however, which is now by far the largest exporter of
cocoa in the Western Hemisphere production remained insignificant
during the earlier part of the nineteenth century. Until the 1890's
the Amazon basin was the foremost producer and exporter of cocoa
in Brazil. In 1851 exports of cocoa from Amazon ports totalled
2,900 tons and this had increased to 6,900 tons by 1891.
DEVELOPMENTS IN COCOA CONSUMPTION
Until the nineteenth century cocoa was consumed only in the form
of drinking chocolate, made from the crushed beans. These contain
over 50 per ceft of fat (cocoa butter) which makes beverages prepared
from the beans unpalatable and difficult of digestion. To counteract
this it was customary in the early days to mix the powdered beans
with.some floury or farinaceous substance in order to counteract the
excess of fat.
An event which powerfully influenced the consumption of cocoa in
Europe and America was the invention, early in the nineteenth cen-
tury, by C. J. van Houten in Holland, of a process whereby the fat
could be extracted from the cocoa bean. Thus arose the manufacture
of drinking cocoa or chocolate from which most of the fat had been
removed, thereby increasing its palatability and digestibility. At the
same time it paved the way for the production of eating chocolate.
This product is prepared by adding sugar, flavourings and additional
cocoa butter to ground cocoa nibs. A later development was the
invention of milk chocolate, the most popular form of eating choco-
late to-day, in which the cocoa and other constituents are com-
pounded with the solids of dairy milk.
These new products met with popular favour and their manufac-
ture was taken up on a large scale in Europe and America. As a
result the demand for cocoa expanded enormously during the latter
years of the nineteenth and the first half of the twentieth centuries.
THE EXPANSION OF THE PRODUCTION OF COCOA
To meet this increasing demand, which naturally led to cocoa com-
manding very high prices on world markets, cocoa production also
increased very rapidly. By 1900 cocoa production had increased to
over 100,000 tons annually, derived forthe most part from America
and the West Indies, although by then Africa was making substantial
contributions to production, with small amounts from Asia and
The development of cocoa production in West Africa proceeded
with astonishing rapidity. It proceeded from the introduction into the
Gold Coast of cocoa planting material from Sao Tom6 by a native
African cultivator. From this introduction the great industries of
the Gold Coast and Nigeria are largely derived. The expansion of
cocoa planting in the state of Bahia in Brazil dates from the
closing years of the nineteenth century. It was the outcome of the
abolition of slavery on the sugar estates of Brazil in 1888. Large
numbers of liberated slaves at that time emigrated to Bahia, where
cocoa growing already existed on a small scale, and they started
growing cocoa on small holdings, encouraged by the high prices for
cocoa then prevailing.
The remarkable manner in which world cocoa production has ex-
panded since the beginning of the twentieth century was well sum-
marized by Mr. L. A. Byles in an address to the 1951 Cocoa Confer-
ence organized by the Cocoa, Chocolate and Confectionery Alliance,
in the following words:
"In 1900 America produced about 81 per cent and Africa 16 per
cent of world cocoa supplies. To-day Africa produces on the average
about 65 per cent of the world's cocoa and has done so for the last
twenty years. America, including the West Indies, produces about
34 per cent and Asia only 1 per cent. At the turn of the century the
leading producers were Ecuador, Brazil, Venezuela, Sao Tom6 and
Trinidad. In the five years immediately preceding the first world war
Ecuador, Sao Tom6, the Gold Coast and Brazil competed for the
first place amongst the world's cocoa producers. In the five years
preceding the second world war the Gold Coast had outstripped
competitors, with Brazil following and Nigeria some way behind.
The Ivory Coast and the French Camero6ns were expanding produc-
tion rapidly and were well ahead of both Ecuador and Sao Tom6
where production had fallen greatly.
"To-day the Gold Coast produces about 35 per cent, Brazil 17 per
cent, Nigeria 14 per cent and the French Cameroons 6 per cent of
the world's cocoa supplies. The past fifty years have therefore seen a
vast shift in the leading centres of production."
It may be added that world production is now averaging between
650,000 and 750,000 tons of cocoa per annum.
THE PROSPECTS FOR COCOA
In the past twenty years world production of cocoa has ceased to
expand at its former rapid rate and is approximately static, mainly
by reason of the heavy toll taken by diseases and pests in Africa and
The Prospects for Cocoa 5
America. This has led to shortages of supply owing to the expansion
of the demand with population growth, and has affected prices for
cocoa which of recent years have risen to unprecedented levels.
Cocoa is at present one of the most profitable crops that can be
grown for export in the tropics, and it seems reasonable to presume
that profitable markets may be expected to continue to exist for many
years to come. In the past, supplies of raw cocoa exceeded demand
at times and this led to low prices, partly, it may be conceded, because
at that time manufacture and distribution had not been geared to the
unforeseen rapid expansion of production, To-day, however, pro-
duction is balanced by improved and expanded organization for
manufacture and distribution and the industry is well equipped to
deal with further expansion of production, should the need arise.
The restrictions which the present high prices for cocoa threaten
to impose on the consumption of eating chocolate and other cocoa
products, can only be countered by an increased world production.
The present limitation to this is imposed by the incidence of pests
and diseases. It seems reasonable to expect that the skill of the scien-
tists, which has successfully overcome similar difficulties in other
agricultural industries, will ultimately succeed in surmounting them
in the case of cocoa.
van Hall, C. J. J. Cacao (Macmillan, 2nd Edition, 1932).
Emeholm, Ivar. Cocoa Production in South America (Gothenburg, 1948).
Burkill. "Article on Theobroma". The Dictionary of Economic Products
of the Malay Peninsula (1935).
Lerbuscher, Charlotte. "The Cocoa Processing Industries". Bull. of the
Imp. Inst. (1947).
Lord Hailey. An African Survey (Oxford University Press, 1938).
Report of the 1951 Cocoa Conference.
Freeman and Chandler. Article on Cocoa in The World's Commercial
THE BOTANY OF COCOA*
History of Cocoa Planting-Natural Habitat-Habit of
Growth-Types of Branches-The Leaves-The Flowers-
Pollination-The Fruit-Cocoa Varieties-Nomenclature of
HISTORY OF COCOA PLANTING
THE genus Theobroma is indigenous to the New World, and wild
species occur from Mexico to Peru, with an apparent centre of origin
in the upper Amazon basin. The cocoa tree, Theobroma cacao L.,
belongs to the lower storey of the lowland forests where conditions
are warm, shady, and humid. It has been cultivated since prehistoric
times by the Indians of South and Central America and opinion is
divided as to whether it now ever occurs in a truly wild state or only
in areas which have at some time or other been interfered with by
man. The Spaniards who landed in Mexico early in the sixteenth
century found cocoa an established product with every indication
that it had been used, and therefore presumably planted, for cen-
turies. The crop, as grown to-day, is much more complex than that
known to the Mexicans, but in spite of its development having taken
place relatively recently, its botanical history is by no means clear.
The Spaniards are said to have planted cocoa in Trinidad as early
as 1525, but it is not known whence they obtained planting material.
There is no good evidence that the tree is native to Trinidad, though
a few wild trees can be found in the forests. These are presumably
escapes from early cultivation and actually bear sufficient resemblance
to Mexican forms to suggest that there may have been an early
importation. Cocoa was certainly being shipped from what is now
Venezuela in 1634 and the material planted there is likewise uncer-
tain. There was probably a native cocoa in the forests which may
have been used, as well as material from the same source as the
Trinidad plantings. The cocoa called "Criollo" (or native) in
Venezuela to-day is rather different from the Mexican type.
Venezuela was the chief producer until about 1830, when it was
passed by Ecuador. A native Ecuadorean type, quite distinct from
By Professor R. E. Baker.
Natural Habitat 7
the Venezuelan, was planted in the latter country. Trinidad was at
that time the third largest producer after Venezuela and Ecuador
and was producing a type of cocoa quite different from either. All
three, however, were producing what are now classed as fine or
The Gold Coast started planting cocoa about 1879 with yet another
distinct type of material, obtained indirectly from Brazil or Surinam,
of a different flavour but superior in hardiness and yield. It is mis-
leading to speak of the cocoas of Venezuela, Ecuador, and Trinidad
as "high quality" and those of West Africa as "inferior quality."
Different kinds of cocoa have different flavours and therefore dif-
ferent uses, but much West African cocoa is now better prepared,
and therefore could be said to be of better quality than the present-
day produce of the older cocoa-growing countries.
Ecologically, all varieties of cocoa appear to be trees of lowland
tropical forests. Their natural habitat includes very wet spots in the
lowest storey of small trees in dense rain forest. The limits of cultiva-
tion are about 200 N. and 200 S., with the bulk of the crop within
100 of the equator, and within these limits most of the main pro-
ducing areas are at low elevations, usually below 1,000 feet. Cocoa,
however, grows well in the Cauca valley of Colombia at 3,000 feet,
though that is probably near the limit. The minimum annual rain-
fall for successful cultivation seems to be about 50 inches, but distri-
bution of rainfall and shelter from wind are more important factors
than total precipitation.
The origin of the tree as an under-storey species in forest is
probably responsible to some extent for the traditional method of
growing it under the shade of larger trees, but it is to be noted that
in this respect the "natural" environment does not necessarily give
the best conditions for high yield. In fact, the heavily shaded trees
in forest usually carry little fruit. Cocoa can survive in heavy shade
that would kill many species, but it can also survive a considerable
degree of exposure, although general experience is that unshaded
cocoa may suffer severe set-backs. The lesson to be learnt from the
forest habitat and from experience in cultivation seems to be the
necessity for protection from wind and the desirability of shade,
except in those instances where experience has shown that shade
may be safely omitted.
The Botany of Cocoa
HABIT OF GROWTH
The various kinds of cocoa differ little in general habit. All are
small trees, attaining a height of thirty feet or so, and with few
exceptions they all have an uncommon and characteristic mode of
branching. The seedling plant forms a straight main stem three to
five feet high, and then forks into three, four, or five main, almost
horizontal, limbs, forming the so-called fan or "jorquette." The
terminal bud is used up in the forking, and further increase in height
is made by a sucker or "chupon" which arises later, usually just
below the jorquette, and grows up vertically between the branches of
the latter to repeat, a few feet higher up, the forking of the main
trunk and form a second storey. An unpruned tree may add a third,
or even a fourth tier of branches, and plantation practice varies, so
that on different estates one may see trees kept to one jorquette and
trees with two or three. In certain wild Theobroma species the
terminal bud is not used up in branching, and growth continues
from above the jorquette, giving the tree a distinctive and very
TYPES OF BRANCHES
There are thus two types of branches, (a) the upright or chupon
type, including the first main axis of the seedling, and (b) the fan
type. Both bear flowers and fruits, but they differ in several other
respects. The chupon type of branch bears its leaves in a J-spiral,
and is determinate in its growth, as sooner or later it always gives
rise to a terminal fan. The fan branch has its leaves two-ranked and
is indeterminate, growing indefinitely and giving rise to laterals of
its own type.
As a general rule, chupons give rise to chupons except in the
jorquette, and fans to fans. There is, however, a certain plasticity
about this so-called "dimorphism" of branching. It is very rare for
a fan to be produced from a chupon below the jorquette, but it is by
no means uncommon for chupons to be produced on fans. The
exception to this rule is to be found in certain Central American
cocoas. These have no chupon branches; the main stem starts from
the seed with spirally arranged leaves, but the spiral quickly opens
into a two-ranked arrangement with no jorquette, and all subsequent
branches are of the fan type. These trees are uncommon in most
countries outside Central America, though a few occur in Trinidad.
The leaves of the tree, when mature, are dark green in colour and
thin but firm in texture. When young they are light green or of
I. A cocoa farm in the Gold Coast
2. A chupon branch of a cocoa tree with
leaves in a j-spiral giving rise to a jorquette
of five fan-branches
3. Cocoa flower, showing the style
surrounded by five pigmented stami-
4. A fan-branch: The leaves are
alternate and in one plane. The
pulvini or swellings on the petioles
can be seen
5. A collection of cocoa pods
In the background are pods from
The group in the middle shows the
range of size and shape found on a
In the foreground are some Calaba-
cillo and Angoleta pods
6. A chupon arising from the
base of a mature tree
7. A cocoa tree about seven years
old grown from a fan-cutting
8. A chupon arising from a fan-
The latter may be removed shortly
and the new tree will then develop
as if it were a normal seedling tree
Habit of Growth 9
various shades of red, and very soft and limp, hanging vertically
from their petioles. Stipules are conspicuous on the young leaves
but are soon shed.
The petiole has a well-marked pulvinus or swelling at each end,
possibly facilitating the turning of the leaf in response to photo-
tropic stimuli. The fan branches make their growth in "flushes,"
the length of the internodes gradually increasing from start of growth
up to a maximum, and decreasing again as the bud returns to a
dormant condition. The stipules of the last-formed leaves of a flush,
being close together, leave characteristic scars on the twig when
growth is resumed, so that the extent of successive flushes can easily
be seen on examination of a branch. The leaves usually persist
through two flushes and are dropped from the third length back
from the terminal bud, so that there are normally leaves of three
distinct ages on each branch.
Theobroma cacao is "cauliflorous," which means that the flowers
and fruits are produced on the older leafless parts of the stem and
branches. In some Theobroma species, such as T. bicolor, the flowers
are produced in the leaf axils of the current shoots. In T. cacao,
although the flowers are produced on the old wood, they arise at
spots which were originally leaf axils. According to Stahel, they
occur in the axils of the reduced first leaves of the axillary branch,
which then normally develops no further. Occasionally on healthy
trees, and more frequently on trees attacked by witches' broom
disease (Marasmius perniciosus), the axillary branch develops into a
small leafy shoot, and in such cases the position of the inflorescence
is very clear.
The flower is quite regular and hermaphrodite, and has the for-
mula K5 C5 A5 + 5 G(5), or in other words, five sepals, five petals,
ten stamens in two groups or whorls, only one of which is fertile,
and a superior ovary of five united carpels. The pink or whitish
sepals are valvate in arrangement; the petals are very narrow at the
base and expanded above into a cup-shaped pouch, beyond which
they end in a relatively broad spatulate tip or ligule. The androecium
or male part of the flower consists of five long, pointed staminodes
and five fertile stamens which, being the inner whorl, stand opposite
the petals. All ten are joined at the base into a very short tube. The
stamens are so bent that their anthers lie concealed in the pouched
portion of the corresponding petals, whilst the staminodes stand
erect and form a sort of ring fence around the style. The stamens
are double, each representing two, fused along their filaments, and
10 The Botany of Cocoa
each has therefore four pollen sacs. The ovary is simple, having five
compartments containing numerous ovules which are arranged
around a central axis in the ovary, and the style is partially divided
into five stigmatic lobes, which usually more or less adhere together.
There is a constriction, at which the flowers absciss, at the base of
The pollination mechanism of cocoa is still imperfectly under-
stood, and presents features of much interest. A conspicuous feature
is the enormous wastage of flowers which normally occurs, and
examination shows that the vast majority are never pollinated. As
a rule, according to several independent estimates, the proportion
of pollinated stigmas is about 5 per cent.
There is no record of what the natural pollinating agent in the
native haunts of the tree may be, and if the flower is examined criti-
cally the conclusion must be formed that the structure is not such as
to facilitate pollination by any of the regular means, but rather to
hinder it. There is neither scent nor nectar to attract insects and, on
the other hand, the pollen is too sticky to be that of a wind-pollinated
plant, neither is the position of the anthers suitable for such a habit,
but distinctly the reverse. In fact, both the position of the anthers,
hidden in the pouched petals, and the ring-fence of staminodes
hindering access to the stigmas, are features incapable of being
regarded by any stretch of a teleological imagination as facilitating
Several investigations in recent years (Harland, 1925; Stahel,
1928; Billes, 1941; Posnette, 1944) have shown fairly conclusively
that pollination is effected by the agency of insects. A certain amount
of self-pollination is effected by small crawling insects, such as flower
thrips and aphides. These, however, are evidently not the only
agents. Flowers on sections of the trunk protected against crawling
insects by sticky bands show a certain number pollinated, presumably
by a flying insect. Furthermore, it has been known since 1931 that
many trees in the Trinidad population are self-incompatible (i.e. set
no fruit with their own pollen) yet some of these are heavy yielders.
Clearly there must be some agent, presumably winged, conveying
pollen from tree to tree. Billes found that a Ceratopogonid midge
of the genus Forcipomyia pollinated cocoa in Trinidad. Two species
-F. quasi-ingrami and Lasiohelea nana-have since been identified
in Trinidad and different species of the same genera have been found
in West Africa, but there may be other winged pollinators, and the
Cocoa Varieties 11
subject needs still more investigation. Unpollinated flowers are
usually shed the day after opening.
The fruit, which is botanically a berry, usually contains from twenty
to forty seeds, each surrounded by a pulp which is developed from
the outer integument of the ovule. The outer layers of cells of this
integument become prismatic in shape during the growth of the
seed, and their contents become highly mucilaginous. At full ripe-
ness they break down and release the mucilage. At lease one import-
ant function of the fermentation to which the beans are subjected
after harvest is the removal of this mucilage by the action of yeasts;
this facilitates subsequent handling and drying of the beans.
As the ripe pods do not open and scatter the seed, nor drop off the
tree, and as the seed will presumably be dead by the time the pod is
decayed, natural dissemination can only be carried out by animals.
Monkeys, rats and squirrels will open the pods for the sake of the
beans from which they suck the surrounding sweet pulp before
spitting them out.
In the brief history of the crop already given, it was recorded that
the first exporter of cocoa to the European markets was Venezuela,
and for this reason it is hardly surprising that the terminology of the
markets is still based on standards applicable to Venezuelan cocoa
more than a century ago. This terminology must be understood.
From the earliest plantings in the late sixteenth and early seven-
teenth centuries up to about 1825, Venezuela grew only one kind of
cocoa. It was not a highly uniform variety because the pods from
different trees varied in colour (some red and some yellow) and to
some extent in size and shape. There was, however, a general and
fairly close similarity between them. The pods were relatively long
and narrow, pointed, conspicuously ridged and furrowed, and warty.
The seeds inside were almost round in cross-section and, when cut
across in the fresh state, either white or pale violet in colour. The
quality was high; in fact, it has never been surpassed, and the small
quantities of this same cocoa now available on the world's markets
are still regarded as the highest quality of all cocoas.
About 1825 another kind of cocoa was introduced into Western
Venezuela from Trinidad. This was much less uniform and included
trees bearing pods that were shorter and relatively broader than those
of the old cocoa, less sharply pointed or in some cases not pointed at
12 The Botany of Cocoa
all, less conspicuously ridged and furrowed, and often entirely
unwarted. Above all, the seeds were somewhat flattened in cross-
section and when cut across showed a deep purple colour in the
cotyledons. This new cocoa was welcomed because it was hardier
than the old kind, grew more strongly, and yielded more, and it was
soon extensively planted. To distinguish the two kinds, the older
was called "Criollo" (native) and the newer "Forastero" (foreign)
or "Trinitario" (the cocoa of Trinidad).
The cocoa from Trinidad, though in the "Fine" category, was
distinctly inferior to the more delicate Venezuelan Criollo. So it
soon came about that on the European markets "Criollo" became
synonymous with "highest quality" and "Forastero" with "lower
quality." Trinidad cocoa from Trinidad naturally fell into the
"Forastero" group in the trade sense, but so did the cocoa from
Ecuador, which at that time was becoming increasingly important.
The Ecuador cocoa was entirely different, botanically, from that of
Trinidad or the "Trinitario" of Venezuela. Furthermore, it was a
native of Ecuador and therefore, in the literal Spanish sense (but not
in the trade sense), "Criollo" there. The Ecuadoreans, however,
happen to use the word "Nacional" rather than "Criollo" to indi-
cate its indigenous status, and so the confusion does not arise. But
the original meanings of "Criollo" and "Forastero" were lost from
that time on in the cocoa market, and the words have to be com-
pletely re-defined to-day in their application to cocoa varieties.
NOMENCLATURE OF COCOA
The "native" (or long-established) cocoas of Mexico and Central
America have white beans and are essentially similar to Venezuelan
Criollo, though superficially distinguishable. They scarcely enter
the export market but to the extent that they do are classified as
"Criollo" and are also classified agriculturally as Criollos. The
original Venezuelan Criollo was introduced to Ceylon, Java, Mada-
gascar, and Samoa, and the produce of these countries came on the
market as Ceylon Criollo," Java Criollo," etc., although the terms,
taken literally, would be absurd.
It should be noted that the distinction between "Criollo" and
"Forastero" is not the distinction between "Fine" and "Ordinary."
All the cocoas so far mentioned are "Fine" cocoas in the modern
sense. The distinction of "Fine" and "Ordinary" is a later develop-
ment, rendered necessary by the increasing complexity of the cocoa
crop as production spread; and it is that complexity which necessi-
tates this lengthy explanation.
Present-day Classification 13
Confusion arose when, about the beginning of the twentieth cen-
tury, there came on the market from West Africa and Brazil cocoa
of another new kind, different from that of any of the Forastero
cocoas hitherto known. It was quite naturally grouped for con-
venience with the Forastero (or "lower quality") cocoa, and the term
now included three separate qualities: (a) Trinidad cocoa, and
Trinitario of Venezuela, (b) Cacao Nacional of Ecuador, (c) West
African and Brazilian cocoas. As the last group increased in pro-
duction it came to dominate the whole market.
We may briefly summarize in a slightly different manner all the
cocoas on the market today as follows: (1) Criollos, the finest of the
"Fine," but almost negligible in quantity, which will apparently
disappear altogether unless special steps are taken to preserve them.
(2) Fine Forasteros, including Ecuador cocoa, Trinidad cocoa, and
cocoa from Trinidad grown in Venezuela, Ceylon, Indonesia, and
a number of other countries of small output. (3) Ordinary Foras-
teros, grown in West Africa, Brazil, and San Domingo.
Botanically, we recognize three groups which correspond almost
exactly with this market division, only the position of Ecuador cocoa
being anomalous. These three groups are:
Criollo Cocoas. We define the Criollos by the characters already
given for the old Venezuelan Criollo population, which will include
also the native or long-established cocoas of Mexico and Central
America, and also of Colombia. They have pods either red or yellow
in colour when ripe, usually deeply ten-furrowed, very warty and
conspicuously pointed; the pod wall is relatively thin and easy to cut,
the seeds are plump, almost round in section, and the fresh cotyle-
dons either white or pale violet in colour. The seed characters are the
most important, as the whole group is variable and occasional trees
may have smooth or scarcely pointed pods, but as a rule all the
characters mentioned occur together. Though their early history is
entirely obscure, it seems likely that the Central American group was
carried up from South America by human agency and is not truly
Amazonian Forasteros. The Amazonian cocoas comprise the
ordinary cocoas of Brazil and West Africa and the Cacao Nacional
of Ecuador. They are called Amazonian because they are apparently
distributed naturally throughout the basin of that river and its
tributaries. They probably originated around the headwaters, but
the cocoas of that region are as yet little known in cultivation.
14 The Botany of Cocoa
Variation decreases down the river and the members of the group
taken into cultivation in Brazil and carried over to West Africa form
a fairly uniform population.
The pods of all Amazonian Forasteros are yellow when ripe, and,
in the better-known representatives in cultivation, they are incon-
spicuously ridged and furrowed, smooth and round-ended or very
blunt-pointed. The pod wall is relatively thick and often has a
woody layer difficult to cut. The seeds are more or less flattened
and the fresh cotyledons are dark violet in colour, sometimes almost
As with the Criollos, the seed characters are the most important,
and more constant than the pod shape, but they are not invariable.
Members of this group, which in some way long ago got over the
Andes into Ecuador, evolved into a variety with plumper seeds and
paler cotyledons than any other known Amazonian Forastero.
That variety is the Cacao Nacional and, on account of those charac-
ters it is a "Fine" cocoa on the market, though its botanical affini-
ties are with the "Ordinary" kinds.
Trinitarios. The Trinitario cocoas are botanically a complex
group, and to explain them we have to go back to history. It has
already been mentioned that the Spaniards are supposed to have
planted cocoa in Trinidad in the sixteenth century and that the
material planted was possibly from Mexico. It is certain that cocoa
was grown in Trinidad in the seventeenth century and that the
variety was a Criollo in the modern sense. But in 1727 something
happened which in the literature is called a "blast"; and whether it
was a hurricane or an epidemic outbreak of disease, it virtually wiped
out the cocoa cultivation of Trinidad. Some thirty years later the
industry was re-established with planting material of a new and
hardier variety of cocoa brought in from Venezuela. Details are
lacking, but there can be little doubt that the importation was from
Eastern Venezuela, and probably it came from the Orinoco valley.
The cocoa concerned was certainly not the Venezuelan Criollo
being grown at that time in Western Venezuela. It was hardier but
of lower quality. We cannot tell whether it was a fairly uniform
Amazonian Forastero or whether it was already a mixture. If uni-
form, it very soon became mixed by being interplanted with the relics
of the old "Trinidad Criollo"; but it seems more likely that it had
already become mixed in the Orinoco basin by the overlapping of
more than one parental type. However that may be, its characters
are those of a hybrid population, and its most outstanding charac-
teristic is its heterogeneity. When some of this cocoa was sent to
Western Venezuela about seventy years after its introduction to
Present-day Classification 15
Trinidad, it was not recognized there as a Venezuelan variety, and,
being quite different from the Criollo grown in that district, was
distinguished as Forastero or Trinitario.
The group of cocoas now included under the term Trinitario is
important for more reasons than its local connection with Trinidad.
When reintroduced to Venezuela, the Trinidad cocoa became popu-
lar there because it was hardier and more productive than the high-
quality but delicate Criollo. Then cross-fertilization took place
with the Criollo trees and when seedlings were raised from them they
were no longer pure Criollo. By selection the Criollo was gradually
supplanted and to-day very little of it is left in pure stands.
The history of Venezuela was repeated both in Ceylon, which grew
Venezuelan Criollo from about 1834 but introduced Trinidad cocoa
about 1880, and in Java which appears to have got Criollo cocoa first
from Ceylon and then got it mixed with a Trinitario introduction in
1888. The process is continuing to-day in the Central American
countries and in Colombia, which have Criollos but have introduced
either Amazonian or Trinidad cocoa and interplanted it with their
own. Wherever we find a hybrid mixture of recent origin we may,
for convenience, call it a Trinitario population. This means that
Trinitarios differ according to their different histories aAd parentages,
but all are highly heterogeneous. It is precisely their heterogeneity
which makes them of the most interest and also of the most promise
to the plant breeder.
The Botany of Cocoa
For a fuller discussion of the different groups of Cocoas and their
Cheesman, E. "Notes on the nomenclature, classification, and possible
relationships of cacao populations." Tropical Agriculture (Trinidad,
1944), 21, 144.
Stahel's finding on the morphology of cocoa flowers:
Stahel, G. Annales du Jardin Botanique de Buitenzorg (1918), Vol. 30.
Information on pollinating insects:
Billes, D. J. "Pollination of Theobroma cacao in Trinidad, B.W.I."
Tropical Agriculture 18, 151 (Trinidad, 1941).
Harland, S. C. "Studies in cacao: I. The Method of Pollination."
Ann. Applied Biology (1925), 12, 403.
Posnette, A. F. "Natural pollination in the Gold Coast, I, II." Tropical
Agriculture 19, 1; 19, 188 (Trinidad, 1942).
Posnette, A. F. "Pollination of cacao in Trinidad." Tropical Agricul-
ture 21, 115 (Trinidad, 1944).
Stahel, G. "Beitrdge zur Kenntnis der Bliiten-biologie von Kakao (Theo-
broma cacao, L.). Reviewed by S. C. Harland in Trop. Agric., 5,
The first reference to self-incompatibility in cocoa is:
Pound, F. J. "Studies in fruitfulness in cacao. II, Evidence for partial
sterility." 1st Annl. Rept. on Cacao Research, 1931. (I.C.T.A.,
Rainfall-Temperature and Humidity-Altitude-
THE climate which usually prevails in the rain-forest zones of large
land masses and on islands in the tropics within about 200 north
and south of the equator is usually suited to cocoa. It is not pro-
posed to deal with the subject of climate exhaustively, but to touch
on some of the main features which affect the cocoa tree.
Cocoa is grown where the rainfall is as low as 45 to 50 inches and
as high as 200 inches. A rainfall of 45 inches seems to be the lowest
in which cocoa has been grown so far without irrigation. There
does not appear to be any evidence of what may be the upper limit
of rainfall in which the crop may be grown. The tree seems to have
considerable capacity for adjusting itself to different conditions of
rainfall; for example, in those parts of West Africa where there is a
dry season of three months or more, the cropping season is well-
defined, and the main crop is borne during three to four months of
the year. There are long periods when the tree bears little or no
fruit. On the other hand, in the Gazelle Peninsula of New Guinea,
where there is no well-defined dry season, the cocoa trees bear fruit
all the year round. The total rainfall and its distribution will, of
course, have to be considered in relation to the type of soil in which
the cocoa is grown. High rainfall on a heavy soil may give rise to
waterlogging; a rainfall which is adequate on a heavy soil may
be inadequate on a lighter soil.
The theory has been advanced that cocoa benefits from a resting
period, i.e., several months of non-bearing, as happens in countries
with a marked dry season. This theory seems to be refuted by
experience in New Guinea where cocoa trees bear all the year round
and where the yields per tree are extremely high.
The distribution of rainfall may have an effect on the seasonal
incidence of certain diseases. An important example of this can be
found in West Africa where, when the rains are prolonged into what
is normally the dry season, there is usually a high incidence of
fungoid disease. In the British Cameroons, where a great deal of the
crop is borne during the rains, losses of pods through fungoid
disease are high.
TEMPERATURE AND HUMIDITY
The cocoa tree, being essentially a tree of the lower forest storey,
reacts unfavourably to sudden changes of temperature or humidity.
On large land masses the direction and force of the wind at different
times of the year may have a considerable effect on both these
factors. Wind blowing from the sea will naturally be moisture-
laden, but winds blowing from inland, such as the harmattann"
winds from the desert in West Africa, have a drying effect and result
in low temperatures at night. Forest belts, windbreaks, and trees
providing overhead shade temper the prevailing winds and help to
maintain stable conditions of temperature and humidity within the
The main factor limiting the growth of cocoa at the higher alti-
tudes is temperature. Where the range of temperature is suitable, it
is possible to grow cocoa up to altitudes of over 3,000 feet. Where
the higher altitudes are subject to prolonged periods of mist and
overcast skies, the cocoa trees are more liable to suffer from fungus
The following tables give information on climatic conditions in a
few cocoa-growing countries. Malaya has, so far, only grown a
small amount of cocoa, but climatically it is suited to the crop.
Even at Tafo in the Gold Coast, St. Augustine in Trinidad, and
Bahia in Brazil, all of which are reckoned to have an adequate
average rainfall, cocoa suffers from drought in seasons when the
rainfall has been abnormally low. In New Britain, with its relatively
high rainfall, the trees-especially young ones-planted on a porous
volcanic soil have had a setback on the rare occasions when the
rainfall has been below normal.
The meteorological data are derived from the following sources:
TAFO: W.A.C.R.L Annual Report 1952-53.
ST. AUGUSTINE, Trinidad: I.C.T.A. (from information given to students).
URUqUCA, Bahia: Figures for 1937 from Cocoa in Brazil, by L. J. Schwarz;
1941-50 figures from Experimental Station, Urunuca.
MALAYA: Report on suitabilityfor cocoa-growing of the territories of Malaya,
Sarawak and British North Borneo, by D. Gillett. (Private Report to
Cadbury Brothers Ltd., 1948.)
RABAUL, New Britain: The Growing of Cacao in Papua and New Guinea
(Appendix 7), by D. H. Urquhart and R. E. P. Dwyer (Cadbury
Brothers Ltd., 1951).
MULNU'U, Western Samoa: Cocoa Growing in Western Samoa (Appendix
1), by D. H. Urquhart (Technical Paper No. 39, South Pacific Com-
The graph is adapted from Le Cacaoyer a Tafo (Gold Coast), by
L. Poncin (Brussels, 1950).
JAN FEB MAR APR NAY JUN JUL AUG SEP OCT NOV DEC
LUKOLELA (Average Annual Total 1548 mm. or 60-9 inches)
TAFO ------ (Average Annual Total 1536 mm. or 60-6 inches)
AVERAGE MONTHLY RAINFALL (1938-47) AT TAFO, GOLD COAST AND
LUKOLELA, BELGIAN CONGO
METEOROLOGICAL DATA OF SOME COCOA-GROWING COUNTRIES
1. TAFO, GOLD COAST (15-year period, 1938-52)
Shade Temp. Average
Mean Mean Mean Rel. Humid. Mean No. of
Month Max. Min. 9 a.m. 3 p.m. Rainfall Wet Days
(degrees Fahr.) (%) (%) (inches)
January .. 914 59-1 85-9 54-1 1-56 3-4
February .. 93-7 61-2 83-7 51-3 3-63 7-3
March .. 93-5 65-8 81-6 54-7 6-09 11-6
April .. 93-7 66-1 80-5 57-9 5-80 11-2
May 92-1 66-6 81-7 62-3 7-07 13-4
June .89-3 66-1 84-7 67-9 8-33 18-4
July 86-8 66-2 86-0 68-9 5-53 13-4
August 86-4 65-0 85-9 61-3 2-79 12-8
September.. 88-0 66-6 85-1 70-6 6-23 13-9
October .. 89-8 66-3 83-1 69-8 8-65 18-0
November.. 90-5 65-0 81-8 65-4 5-08 11-0
December 90-6 62-7 84-2 61-4 2-44 5-0
Total for year .. 63-20 139-4
2. ST. AUGUSTINE, TRINIDAD (21-year period, 1929-49)
Mean Mean Sunshine Humidity Mean Average
Max. Min. Dly. Av. Mean Min. Rainfall No. of
(degrees Fahr.) (Hrs.) (%) (inches) Wet Days
January .. 84-0 68-0
February .. 85-0 67-0
March .. 86-0 68-0
April .. 87-0 71-0
May .. 88-0 72-0
June .. 86-0 72-0
July .. 86-0 72-0
August .. 87-0 71-0
September.. 87-0 72-0
October .. 87-0 72-0
November.. 86-0 71-0
December.. 85-0 70-0
6-7 63-0 8-6 22-0
7-2 63-0 8-6 23-0
6-9 63-0 9-8 23-0
6-5 62-0 7-9 19-0
7-0 62-0 6-4 17-0
7-0 63-0 7-8 28-0
7-1 62-0 6-4 20-0
Total for year .. 67-8 226-0
3. URUgUCA, BAHIA
Max. Min. Ave.
Mean Shade Shade Hum.
(degrees Fahr.) (/%)
January .. 77-5 92-0 64-4 84-6
February .. 77-0 91-6 66-2 87-1
March .. 77-7 94-0 67-5 84-2
April .. 75-2 94-3 64-4 87-9
May .. 73-4 95-4 57-6 85-3
June .. 70-7 93-2 59-4 88-4
July .. 694 88-0 58-3 88-0
August .. 70-3 892 55-4 85-8
September.. 70-3 89-6 53-6 86-0
October .. 74-8 93-2 60-8 85-2
November.. 76-8 93-0 61-9 88-6
December.. 77-2 94-3 63-5 85-2
Total for year
Rainfall Wet Days
4. MALAYA (Rainfall)
No. of years recorded: 58 12
(average in inches)
January .. .. .. .. 668 11-77
February .. .. .. .. 6-18 7-51
March .. .. .. 920 10-72
April .. .. .. .. .. 1073 5.35
May .. .. .. .. 848 5-21
June .. .. .. .. 5-07 5-36
July .. .. .. .. .. 413 5-34
August .. .. .. 6-31 5-61
September .. .. 7-33 6-31
October .. .. .. .. .. 11-09 16-22
November .. .. 10-19 31-98
December .. .. .. .. 9-53 23-40
Total for year .. 94-92 134-77
5. RABAUL, NEW BRITAIN (25 years)
Temperature Rel. Humidity
Mean Mean Average Mean Mean Mean
Max. Min. Monthly Max. Min. Rainfall
(degrees Fahr.) (%) (%) (inches)
January .. 90-7 73-5 82-1 79-0 72-0 14-13
February 88-9 73-8 81-3 79-0 72-0 10-44
March .. 88-4 73-4 80-9 83-0 75-0 9-42
April .. 89-3 74-0 81-6 83-0 72-0 9-80
May .. 88-9 73-9 81-4 79-0 72-0 5-17
June .. 88-5 73-8 81-1 79-0 72-0 3-62
July .. 88-7 72-8 80-7 87-0 72-0 5-59
August .. 88-8 73-5 81-1 79-0 72-0 4-40
September 89-8 73-6 81-7 75-0 72-0 3-65
October .. 90-3 73-6 81-9 75-0 68-0 5-25
November 90-8 74-1 82-4 76-0 76-0 6-30
December 90-4 73-4 81-9 75-0 72-0 10-19
Total for year ..
6. MULINU'U, WESTERN SAMOA
Mean Mean Mean
Month Monthly Max. Min.
January .. 79-51 85-1 75-2
February.. 79-50 85-3 75-2
March .. 79-53 85-6 75-0
April .. 79-43 85-7 74-8
May .. 78-98 85-3 74-1
June .. 78-37 84-5 73-0
July .. 77-77 83-9 72-5
August .. 78-25 84-1 72-8
September 78-57 84-4 73-4
October .. 79-03 84-8 74-0
November 79-12 85-1 73-1
December 79-48 85-1 74-8
Mean or Total:
Year .. 78-96 84-9 74-0
Wet Season 79-40 85-2 74-6
Dry Season 78-24 84-2 72-9
No. of years 62 61 61
.. 87-96 186-1
Avge. no. of
Sun- Rel. Mean Wet Cloudi- Wind
shine Humidity Rainfall Days ness Speed
(hours) (%) (inches) (8ths) (mph)
178-3 84-7 17-54 23 5-4 5-8
163-0 84-8 14-94 20 5-2 5-9
199-8 84-8 13-67 21 4-9 5-2
211-5 84-5 9-77 18 4-6 5-3
222-0 83-9 6-81 15 4-2 6-0
224-1 82-3 5-28 12 3-8 7-7
245-2 81-7 3-52 12 3-6 8-1
249-7 80-4 3-77 12 3-6 9-4
235-5 81-2 5-45 13 4-0 8-6
229-2 81-5 7-11 15 4-3 8-1
203-1 82-8 10-26 19 4-8 6-4
181-9 83-5 14-77 21 5-1 6-4
112-89 201 4-5 6-9
57-51 83 5-1 6-1
18-02 49 3-8 8-5
62 61 56 19
(a) 24-hourly values.
Agents-Soil-crumb-Forest Soils-Soil Depth-Classifying
Soils on a Root-room basis-Planting Distance-Effects
of Forest-felling-Functions of Shade-Soil Erosion-
Rehabilitation of Worn-out Cocoa Lands-Mulching and
Mulches-Effects of Mulching: Use of Fertilizers-Root-
COCOA soils may best be considered from the point of view of root-
room; that is, the volume of soil which is fully occupied by roots
when the tree has reached maturity. To be completely effective, the
rooting volume of a soil must contain at all times sufficient water,
air, and available nutrients to meet the requirements of the growing
tree and of the developing crop. In order that a soil may be capable
of satisfying these requirements, it must possess a highly porous
structure and a relatively large content of clay, and it must not
hinder root penetration.
Certain sandy soils possess all these desirable features, so long as
their particle diameter is sufficiently large to provide pores of a size
big enough to permit rapid drainage of water, free ventilation of air,
and easy root penetration, assuming always that the prevailing
rainfall is high enough and the showers sufficiently frequent to keep
the sand continuously moistened.
Free-draining sands have a minimum particle diameter of about
0-5 mm. which corresponds to a minimum pore-size of about
0-2 mm. Root-tips range in size from 0-5 to 0-1 mm., so that free-
draining sand will not impose undue restrictions on root growth.
The pore-space volume of sand at closest ("cannon-ball") packing
is 24-5 per cent of its total volume. This may be regarded as the
minimum total pore-space for a freely-drained and well-aerated
sand having particle size above 0-5 mm. diameter.
By Professor F. Hardy, C.B.E.
Ft. Surface root mat
- Leaf litter
- Dark, grey-brown humic
Mid-brown sandy loam
ts arising from Quartz gravel
tap either grow / Ironstone Concretions
ards or grow Red Clay
nwards into the
on reaching RED CLAY LAYER
MOTTLED CLAY LAYER
/ ; /
i/ //////4Z /
/ ~V~%/ / /
/N /ROTTEN ROCK LAYER
/ / Containing boulders
/ // of undecomposed rock
DIAGRAMMATIC PROFILE OF THE RED WELL-DRAINED SOIL OF THE
UPLANDS IN THE GOLD COAST SHOWING HOW THE TYPICAL COCOA
ROOT SYSTEM EXPLOITS THE VARIOUS LAYERS
When wetted and drained, a mass of sand contains its water solely
as films around the solid particles and as wedges between them,
leaving most of the pore-space open for drainage and ventilation.
The plant roots obtain their water from these wedges and films
which, however, must be continually replenished by rain, otherwise
the sand soon dries out. Hence, unless the rainfall is suitably dis-
tributed, sandy soils are useless for cocoa-growing, quite apart from
the fact that their component grains may consist mainly of inert
quartz which, of course, is entirely incapable of providing plant
Better than sands for cocoa-growing are clay-loams, consisting of
stable aggregates of fine sand, silt, and clay, which behave like
coarse sand grains and yet have the important additional advantage
of a much greater moisture-holding capacity because of the well-
known property of clay for absorbing water. Such soils do not
depend as much as sands on the vagaries of the rainfall, and because
of their clay component they are also more likely than sand to
contain nutrient substances.
The total pore-space of a well-aggregated clay-loam may be as
high as 66 per cent (corresponding to an apparent specific gravity
of about 0-90), of which about one-half (33 per cent) will be filled
up with water when the soil is wetted, owing to absorption by the
clay component which swells up to this extent when moistened,
leaving the other half of the total pore-space (33 per cent) quite
empty. The absorbed water is sometimes referred to as "capillary
water" on the assumption that clay contains a large number of very
minute capillaries that can hold water strongly against the pull of
gravity though they cannot hold it with sufficient force to resist
completely the pull exerted by plant roots. The rest of the pore-
space (33 per cent) in a moistened aggregated clay-loam is called
"non-capillary" pore-space. It comprises pores large enough to
allow rapid removal of water. The non-capillary pores are full of
air when a clay-loam is completely drained. They comprise the
main ventilating system of the soil, and they are large enough also
to allow roots to grow freely through them. Among the naturally
occurring larger non-capillary pore-spaces are old root-traces,
worm-holes, insect-cavities, termite-channels, cracks, and fissures.
These all help to drain the soil after rain and to allow air to circulate
freely within it.
SOIL-AGGREGATE CEMENTING AGENTS
Since the best cocoa soils are undoubtedly aggregate-structure
clay-loams it is important to know what particular agents are respons-
ible for the formation and the stabilization of soil aggregates.
Recent research has shown, first, that aggregates are formed by the
alternate swelling and shrinking caused by repeated wetting and
drying of a soil, and secondly, that the chief agent which cements,
fixes, and stabilizes the aggregates is the sticky mucilage produced
by certain bacteria and blue-green algae that live in decomposing
Thus, aggregate structure is best developed where humus is abun-
dant. Doubtless other agents besides mucilage are concerned in the
cementation and stabilization of soil structure; for example, hydrous
ferric oxide and calcium carbonate. Ferric oxide is mainly respon-
sible for red and brown colours in aggregated soils, and calcium
carbonate (when combined with humus) for the jet-black colour of
the highly aggregated soils known as Rendzina or "humus-car-
bonate" soils which develop over marlstones and calcareous clays.
The commonest kind of aggregate that is stabilized by mucilage
derived from soil organic matter is usually rounded, loose, and
rough-surfaced. It is commonly termed "soil-crumb." The size of
crumb aggregates ranges from over 5 mm. to less than 0-2 mm. An
average sample somewhat resembles coarse bread crumb.
Soil-crumb generally contains over 5 per cent of humus, and
sometimes as much as 20 per cent, as well as a correspondingly high
content of nitrogen. The ratio of its content of carbon to that of
nitrogen (the "carbon-nitrogen-C/N-ratio") is mostly well over
12, which, to the soil chemist, implies that its organic matter com-
ponent is not completely broken down or "humified" so that it is
capable of supporting a large population of micro-organisms, such
as soil bacteria. In addition to a high content of nitrogen, crumb
usually contains relatively large amounts of available phosphate and
Soil-crumb not only possesses ideal physical properties, but it
also serves as a rich storehouse of plant nutrients. It may be
regarded as one of the most important and valuable natural products
in the world.
The thickness of the crumb layer varies greatly in cocoa soils,
depending on various circumstances, including the past history of
the soil. Natural forest soils, which are most generally the imme-
diate predecessors of cocoa soils, may first be considered.
The kind of forest that develops under the particular climate that
is suitable for the growth of cocoa is known as "Evergreen Seasonal
Forest." It generally consists of from three to five distinct storeys.
The uppermost storey comprises a relatively small number of
"emergents," which are exceptionally large trees that tower above
all the others, often to a height of 150 feet. The storeys below form
more continuous but separate canopies of different heights. The
lowest canopy is the undergrowth. Lianes or creepers are abundant.
Such a forest sheds its leaves continuously and the amount of ground
litter that collects may be large. The litter forms a thick layer over
the forest floor. Among the component trees of the forest may be
several species of Leguminosae which enrich the soil with nitrogen
taken up by bacteria living in nodules on their roots.
Where there is an underlying soil of suitable texture (mechanical
composition), such as clay-loam, the products of decomposition of
the forest litter are carried down into the mineral soil below by
various soil animals, notably worms, and in due course soil-crumb
is formed. Where the parent rock and the climate are suitable, and
where undulating topography permits free external drainage, maxi-
mum development of forest vegetation occurs and, given sufficient
time, the thickness of the final crumb layer may be considerable. As
it is extremely well aerated and protected from drying-out by the
cover of litter over it, crumb soil is a most favourable medium for
root-growth and in forest soils is generally fully occupied by roots.
The crumb-soil roots are fine and fibrous and lie in close contact
with the decomposing litter from which they absorb nutrients
directly or through the agency of threads of fungus (mycorrhiza)
which are commonly associated with forest tree roots. The fibrous
superficial roots seem to have another function besides "feeding"
on the rotting litter, in that they may manufacture small quantities
of highly active growth-promoting substances which greatly help in
the development of trees.
The transition between true soil-crumb-with its dense mass of
fibrous roots-and the soil below is generally gradual, the structure
within the rest of the humic soil-layer being coarser and more
"nutty" or cloddyy," or even "blocky."
As a good example of a well-structured soil originally developed
28 Cocoa Soils
under Evergreen Seasonal Forest, may be cited the so-called "Choco-
late Soil" of Trinidad. This is derived from an uncommon rock
known to geologists as glauconitic calcareous sandstone, which is
exposed in certain places in the Central Range. The crumb-layer of
the Chocolate Soil is from one to three inches thick, or even more,
and humic penetration goes down to twelve to thirty-six inches or
more. The subsoil shows a well-marked nut to small clod struc-
ture, within which roots readily ramify. A similar deep soil, derived
from an igneous rock called granodiorite, occurs in the Gold Coast
where it has been extensively used for cocoa-growing.
By contrast, where the parent rock is not suitable to the maximum
development of forest vegetation because of its mineralogical and
chemical composition, and/or its compact or "massive" physical
constitution which impedes downward drainage, the thickness of
the crumb layer may be relatively small or even altogether absent.
In the Northern Plain in Trinidad, certain alluvial silty-clays are
widespread and were once occupied by under-developed Evergreen
Seasonal Forest. These clays have given rise to shallow acidic soils
with high "perched" water-tables, in which crumb-soil is only
sparsely represented. The hard soil immediately below the crumb is
scarcely cracked, and humic penetration is usually less than six
inches. These soils, when freshly cut out of the forest, supported
good stands of cocoa, but they rapidly deteriorated after about
twenty years, until now they can only be regarded as marginal for
In the Gold Coast, cocoa soils developed over certain phyllites
(Birrimian), clay-shales (Voltaian and Buem), and quartz-schists
(Akwapimian), have also proved to be unprofitable for similar
It is evident from a consideration of these examples that the depth
to which different soils develop an aggregate structure stabilized by
humus products or by other cementing materials may vary greatly.
It depends partly on the climate, which chiefly decides the kind of
forest that arises, and partly on the kind of parent rock, which deter-
mines the luxuriance of the forest and the amount of litter that
accumulates, as well as the ease with which humus becomes incor-
porated into the mineral soil. Thus, the amount of root-room
(defined at the outset as the volume of the soil whose physical
properties are favourable to the maximum development of roots,
mainly because of its ideal water and air relations) may range in
Effects of Forest-felling 29
depth from almost zero to as much as three or four feet. At the one
extreme, where there is little or no humic penetration, roots can only
grow and ramify upon and over the surface, being unable to force
their way into the compact unstructured soil below, except down the
sparse cracks that may be formed as the soil dries out. At the other
extreme, where organic penetration is deep and the humic soil
possesses throughout an open porous structure, roots are able to
ramify profusely within the whole soil-mass. Between these extremes
most normal productive soils occur.
CLASSIFYING SOILS ON A ROOT-ROOM BASIS
The root-room concept provides a reasonable method of classify-
ing soils on a physical basis. If combined with some means of
expressing nutrient status, based for example on chemical analysis,
a complete practical scheme of soil classification might be elaborated
which in the simplest form would comprise eight categories, namely:
(i) deep rich sands, (ii) deep poor sands, (iii) shallow rich sands,
(iv) shallow poor sands, (v) deep rich clays, (vi) deep poor clays,
(vii) shallow rich clays, and (viii) shallow poor clays. This scheme
has been effectively applied to Trinidad cocoa soils.
I PLANTING DISTANCE
One important advantage of knowing the root-room of a given
soil is that it provides a means of determining planting distance,
which clearly should be greater for shallow soils having small root-
room than for deep soils having large root-room. This presupposes
that close planting will not cause undue interference between
adjacent tree canopies, but if it occurs it may easily be adjusted by
\ EFFECTS OF FOREST-FELLING
When forest is felled for the establishment of cocoa plantations,
great care should be taken not to expose the bare soil to the direct
beating action of rain nor to direct sunlight. This may be achieved
by leaving some of the largest trees to form a "shelter wood," or by
planting "ground shade," consisting of appropriate kinds of banana,
tannias cocoyamss), cassava, or similar rapidly growing leafy plants,
or small shade-trees such as Gliricidia, Cassia, Tephrosia, Leucaena,
which are leguminous plants, or non-leguminous weed species having
similar habit. More permanent shade such as immortelle (Ery-
30 Cocoa Soils
thrina spp.) may be planted along with the cocoa at suitable spacing.
If the cocoa crop is subsequently planted through this ground-shade,
and both cocoa and shade (including the permanent shade) are care-
fully tended, the transition from forest to cocoa need not be fraught
with danger to the important crumb layer of the soil.
Failure to observe these precautions may result in the rapid
destruction and loss of the crumb and of some of the well-structured
highly humic soil below. Within a few weeks, the whole of the rich
top layer of structured humic soil may have disappeared under the
combined action of beating rain and strong sunlight, and the forest
accumulations of centuries will have been squandered and wasted.
Experimental measurements made in the Arena Forest Reserve,
Trinidad, have shown that the clear-felling of the Evergreen Seasonal
Forest increases the evaporating capacity of the air four and a half
times, mainly because it lets in sunlight and wind. The amount of
radiant energy reaching the forest floor is increased twelve times by
felling, and the range of shade temperature is doubled. The moisture
content of the top six inches of soil (a loose sand) is reduced during
the dry season by two-thirds. The organic matter content of the soil
in all layers down to twenty-four inches is diminished considerably
through enhanced oxidation and the C/N ratio is appreciably
lowered. Marked deterioration occurs within eight weeks after the
felling. Grasses and agricultural weeds rapidly invade the exposed
soil and natural forest regeneration is consequently greatly retarded.
At first, a large increase in the amount of leaf litter follows the
death of the fallen trees. Branches and trunks contribute to the
organic detritus in the form of fungus-rotted wood, and frass pro-
duced by burrowing insects. When burning accompanies the felling,
the resulting plant-ash temporarily raises the mineral content of the
soil and greatly reduces its acidity because it contains alkalis.
Burning may also lower the soil's content of nitrogen. These results
may alter the kinds of micro-organisms that inhabit the soil, fungi
being gradually replaced by bacteria.
FUNCTIONS OF SHADB
Shade trees and ground-shade shrubs contribute considerable
amounts of nitrogen to the soil by their ropt-nodules, leaves, twigs,
Root-nodules of immortelle trees in Trinidad contain over 4 per
cent of nitrogen, leaves contain 2 to 3 per cent, and flowers 3 to 6
per cent. The amount of nitrogen contributed by the fall of flowers
alone in one year is 20 lb. per acre. Cocoa beans, 500 lb. per acre,
Soil Erosion 31
remove about 12 lb. of nitrogen per acre, so that there is a net
gain of 7-5 lb., equivalent to nearly 40 lb. of ammonium sulphate
fertilizer per acre.
The idea that the only functions of shade trees are to diminish the
intensity of incident light and to protect the cocoa trees from exces-
sive evaporation caused by moving air may not be the whole truth.
The name once used for the immortelle tree in Trinidad by the old
Spanish cocoa planters was madre de cacao (mother of cocoa),
suggesting nourishment. Possibly the contribution of nitrogen to
the soil by the deliberate planting of leguminous trees among the
cocoa, either as shelter or shade, may be considerable, judging by the
fact that old shaded cocoa in Trinidad does not respond to nitro-
genous fertilizers, whereas unshaded cocoa, both in Trinidad and in
Grenada, responds markedly.
Sheet erosion, caused mainly by flooding, successively removes
leaf-litter, crumb-soil, and some humic topsoil, and so progressively
exposes layers of diminishing organic matter content and falling
C/N ratio. Where the soil is shallow and the cocoa's root system
(including horizontal woody roots) is superficial, sheet erosion may
severely damage the tree by dissecting out the roots and removing
or injuring many of the branched terminals and active "feeding
roots." Unless the soil losses are rapidly made good by the forma-
tion of new soil, the rooting volume becomes restricted by the
removal of the best-structured and the most highly-aerated upper
portion. At the same time, the supply of nutrients is greatly
decreased. Diminution of the amount of crumb-soil and of the next
few inches of highly humic soil below it is probably the main cause
of soil deterioration that follows forest-felling and exposure of the
land to rain, wind, and sun.
By means of simple pot-tests-growing a test-plant, such as
tomato,,in samples taken from each layer-the relative fertility of
the crumb layer and of the layers that occur successively below it
may be compared. The test is well worth making since the results
are usually most spectacular. At the end of the trial, the crumb-soil
will generally be found to be still well-aggregated, highly permeable,
and completely filled up with roots, whereas the sub-soil (being less
stable) may have lost its open structure, and "run together" some-
what, and it may be less fully occupied by roots.
Loss of litter and soil-crumb and of some of the humic soil below
brings the less fertile soil to the surface. The possibility of utilizing
32 Cocoa Soils
this for growing cocoa, or of re-establishing from it a highly fertile
soil, depends largely on the mineralogical composition of the parent
rock from which the initial soil was generated. If this is rich in
nutrient-bearing minerals, as is the glauconitic sandstone of Trinidad
and certain of the more basic igneous rocks of West Africa, re-
generation is usually rapid, once second-growth vegetation has
become established or the missing nitrogen is added as fertilizer or
manure. If, on the other hand, the parent rock contains only a small
proportion of nutrient minerals, regeneration of a fertile soil by
natural processes is long delayed, unless complete fertilizers or
manures are skilfully used. Only detailed soil surveys can determine
the potentialities of eroded or worn-out soils for rejuvenation under
proper treatment, and the extent and distribution of soil types having
REHABILITATION OF WORN-OUT COCOA LANDS
The rehabilitation of old cocoa fields is likely to be more success-
ful if it takes the form of partial replacement rather than complete
removal of the old cocoa by clear-felling before the replanting. This
conclusion follows from the principle, mentioned in an earlier para-
graph, of the "shelter-wood" system, so widely used at the present
day by foresters in producing timber plantations from natural tropi-
cal forest by selective thinning. Protection of the soil, the mainten-
ance of the right atmospheric conditions near its surface, and the
conservation of the crumb-soil layer with its attendant cover of
decomposing litter, should be the essential aims in attempting to
rehabilitate old cocoa lands. Where soil erosion and soil deteriora-
tion have gone on to such an extent that yields have drastically
declined, the process of building up a fresh crumb layer and of
raising the organic status of the top soil may prove to be difficult,
lengthy, and costly. The process, in effect, is an attempt to reinstate,
within the cocoa plantation, the original forest soil and the charac-
teristic atmospheric conditions of the forest. The methods available
are limited, because they must not only be efficacious, but they must
also be economical and cheap.
MULCHING AND MULCHES
A great deal can be done to restore the soil by the use of mulches
where these are readily obtainable. Among the naturally moist
mulching materials that are suitable are cut-bush and grass, such as
grow in waste places and waysides, or may be specially grown for
Effects of Mulching: Use of Fertilizers 33
the purpose (possibly with the use of fertilizers) in abandoned fields,
on barren hill-slopes, and rocky places unsuited to the profitable
cultivation of crops.
The actual species of bush and grass that might be used for mulch
will naturally depend on the suitability of the particular plants which
grow in the vicinity or which can easily be introduced from outside.
In Trinidad, any of the species of shrubs mentioned earlier as suit-
able for ground-shade might also be suitable for mulching, particu-
larly Gliricidia which sets roots easily, grows rapidly, and produces
abundant shoots which, when lopped off, provide good mulching
material in considerable quantity. Strips of land and paths between
cocoa fields may be planted up with suitable mulch-bushes or grass,
or the plantation may be replanted in blocks to allow mulch bushes
or grass to be grown around or between the blocks.
Among the dry vegetable waste-products that might be used as
mulch are sawdust, wood-shavings, straw, stover, and sugar-cane
bagasse. Where these may be obtained readily and cheaply, they are
highly beneficial when applied in layers, say, three to six inches thick
and allowed to rot down, appropriate and timely replenishment
being made so as to maintain a constant covering. Pen manure or
other organic manures, when available and cheap, may also be used,
not only as mulch, but also as nutrient suppliers.
EFFECTS OF MULCHING: USE OF FERTILIZERS
The use of mulches in cocoa plantations is mainly to provide a
suitable medium for the development of the cocoa root-system by
maintaining a highly porous layer which is well-aerated and highly
retentive of water. In addition, mulches supply variable but often
considerable amounts of plant nutrients, namely nitrogen, phosphate,
and potassium, as well as other essential elements, including trace
elements such as iron, manganese, magnesium, zinc, and copper.
Moreover, these nutrients are liberated slowly but continuously by
mulches which, in contrast with fertilizers, supply large quantities of
nutrients at one time. When a large and healthy cocoa root-system
has been established, further benefit may be obtained and the natural
supply of leaf litter greatly increased by judicious use of fertilizers,
such as ammonium sulphate, superphosphate, and potassium sul-
phate. Care must be taken, however, to use these fertilizers in
balanced proportions. In order to achieve this, the help of the ana-
lytical chemist should be sought for the purpose of checking nutrient
uptake by periodic leaf analysis.
By means of mulches and fertilizers skilfully used, eroded and
34 Cocoa Soils
deteriorated cocoa soils may be rapidly rejuvenated and the growth
and vigour of the trees greatly increased so that the normal cycle of
nutrient circulation, involving the accumulation and decomposition
of leaf litter, is soon reinstated. Eventually, the amount of the mulch
dressings might deliberately be diminished and the quantities of
fertilizers reduced and adjusted, so as merely to make good the
losses brought about by the removal of the crop, thus materially
reducing the cost of mulching, which is an expensive operation.
Cocoa beans in Trinidad contain approximately 2-4 per cent of
nitrogen (N), 1-2 per cent of phosphate (P20), and 1.9 per cent of
potash (K20). An annual crop of 500 lb. of beans per acre therefore
removes from the soil about 12 lb. of N, 6 lb. P205, and 9-5 lb. K2O,
equivalent to a dressing of 60 lb. of ammonium sulphate, 33 lb. of
superphosphate, and 19 lb. of potassium sulphate per acre, or about
6 oz. of mixed fertilizer per tree per year.
Root systems characterized by tap-root domination are capable
of fully and rapidly utilizing rich deep soils with ample rooting
volume. The young vigorous thin tap-root which develops from the
radicle of the germinating cocoa beans, or from the base of a chupon
or sucker, is able to grow between the soil structure units or down a
convenient small crack, until it reaches a water-table or penetrates a
great distance into permeable moist subsoil. Once established, it
rapidly thickens into a conical-shaped object which puts out whorls
and tiers of horizontal secondary woody roots which, with their
ramifying branches, explore the whole of the soil volume and
abstract large quantities of available water therefrom. At the same
time, surface-feeding roots grow out from the base of the young stem
and occupy the crumb layer and the decomposing under-part of the
litter, from which they obtain an abundant supply of nutrients.
Many articles on Cocoa Soils by Professor Hardy and others have
appeared in Tropical Agriculture and in Reports on Cacao Research
(Imperial College of Tropical Agriculture, Trinidad), but they are too
numerous to quote in detail.
Detailed descriptions of some cocoa soils are given in:
(1) the following numbers in the series Studies in West Indian Soils:
Hardy, F., Akhurst, C. G., and Griffith, G. III, "The cacao soils of
Tobago" (Trinidad, 1931).
Hardy, F., McDonald, J. A., and Rodriguez, G. IV, "The cacao soils
of Grenada" (Trinidad, 1932).
McDonald, J. A., Hardy, F., and Rodriguez, G. VII, "The cacao soils
of Trinidad": (a) Montserrat district (Trinidad, 1933).
Hardy, F., Duthie, D. W., and Rodriguez, G. X, "The cacao and forest
soils of Trinidad": (b) South-central district (Trinidad, 1936).
(2) the following articles in Reports on Cacao Research:
Hardy, F., and Rodriguez, G. "Some Gold Coast cacao soils", I.
Hardy, F., and Amoroso-Centeno, E. H. "Some Gold Coast cacao
soils", I. (6th and 7th Annual Reports, Trinidad, 1937 and 1938.)
Other informative articles are:
Chenery, E. M. "Digest of cacao soil of Trinidad and Tobago" (Cocoa
Research Conference, 1945).
Charter, C. F. "Characteristics of principal cocoa soils" (Cocoa Con-
ference, London, 1949).
THE COCOA PLANTATION (1)
ESTABLISHMENT AND MAINTENANCE
I. PRELIMINARY PREPARATION
Overall Considerations-Choice of Site-Soil Assessment-
Communications, Water Supply, etc.-Planting Material-
Preliminary Operations-Subsequent Operations.
THIs chapter describes in their sequence the operations entailed in
laying-out a plantation and in its subsequent care. Some of the points
are discussed at greater length in other chapters.
No description of plantation practice could cover all the various
methods employed in the tropical countries where cocoa is grown.
Variations are sometimes dictated by climate and soil, by the type of
labour available, and by traditions and fashions evolved in each
While actual practice varies, the basic principles which make for
the profitable growing of cocoa are similar. The planter who would
make a success of the work in one part of the world would be most
likely to make a success of it in another.
CHOICE OF SITE
The choice of site for a plantation will be dictated by certain basic
Although in the past, sound judgment based on experience guided
the more successful planters in their selection of suitable land for
cocoa, many plantations of cocoa and other tropical crops have been
sited on unsuitable soils. The assumption that soils which carry
dense forest must necessarily be productive if the forest is replaced
by a plantation has led to much disappointment. It may also be
misleading to judge the quality of the soil by its cover in the absence
of an intimate knowledge of the type of flora that indicates fertility.
Preliminary Preparation 37
The African peasant built up the greatest cocoa-growing industry
in the world without the aid of scientific knowledge, as we understand
the term. He achieved success by growing cocoa widely; where it
grew well, he grew more of it. In course of time wisdom born of
experience prompted him to test the suitability of the soil for cocoa
by planting a few trees in advance of any general planting, and he
thus acquired a considerable degree of judgment.
This method of trial and error was sufficient for a peasant com-
munity at a certain stage in its progress, but for the prospective
planter at the present time it is not a practical way of choosing land
Where such services are available, the assistance of the Depart-
ment of Agriculture or Research Institute, with staff trained in the
study of soils, or the advice of experienced local planters, will be
sought. In the absence of these, large companies contemplating
development in unsurveyed territory would normally import the
necessary skill for their own guidance. In assessing the suitability of
a new area, the condition of growth of certain forest plants or farm-
ing crops, such as bananas, plantains, and tannias, the luxuriant
growth of which is accepted as indicating good conditions for cocoa,
would be noted. Similarly, the presence of certain trees which are
known to thrive on poor soils or which are indicative of water-
logged or other conditions unsuitable for cocoa would be observed.
In the absence of professional skill or guidance on the spot, anyone
with a working knowledge of soils can gain a great deal of informa-
tion by the use of a soil auger. An ordinary carpenter's auger,
about 1l inches in diameter, can be converted for the purpose by
having the stem lengthened to about 4 feet. It can probe the ground
and bring up enough of the soil to give an indication of its consti-
tuents, the depths of its various layers of heavy or light soils, its
general texture and its capacity for drainage or retention of moisture.
Soils in the tropics are liable to vary widely within a small area, and
a simple survey with a soil auger, used up and down the site, will
often provide more useful information than any other form of
investigation. A preliminary assessment of the acidity and the
presence or absence of potash, etc., can be made by the use of soil
examination kits. Such assessment should be supplemented by a
report on soil samples by an appropriate authority.
Soils which will sustain the growth of the cocoa tree must con-
tain enough clay to enable them to retain sufficient moisture to
38 The Cocoa Plantation: Establishment and Maintenance
assure the growth of the plant through dry periods, but it must
not be so heavy as to impede drainage or the circulation of moisture
The extent to which organic matter or humus is present in the
surface layer may decide at the outset whether cocoa can or cannot
be established. Organic matter helps to keep a clay soil friable and
makes a sandy soil more retentive of moisture. In addition to
improving the physical character of the soil, organic matter is the
medium from which the feeding roots will draw most of the plant's
nourishment. The care with which the accumulated organic matter
is conserved when opening up land for planting, and the skill with
which it is maintained and augmented throughout the life of the
plantation will greatly influence the productivity of the trees.
COMMUNICATIONS, WATER SUPPLY, ETC.
Accessibility by road or water is important as means of communi-
cation have an important bearing on costs.
Water supplies must be studied from the point of view of the needs
of the labourers and also of the nurseries.
The number of labourers and the amount of accommodation
required for them, and also the size and equipment of the buildings
necessary to carry on plantation operations, will be calculated in
relation to the size of the venture planned.
Where circumstances permit, it is cheaper in the long run to erect
the more expensive permanent buildings at an early stage, rather
than to put up temporary buildings which are later to be replaced
by permanent structures. If temporary buildings are made they
should be such that they will last ten years at least without requiring
major repairs. The chief accommodation required will be housing
for labour, overseers, and owner or manager, and houses for
fermenting and storage.
A number of roads will be required in the early stages, but a more
complete road system will be developed gradually. A cambered
road with offsets leading to deep holes to take the run-off is much
better than one with deep ditches on both sides. Nowadays,
even the smaller tractors can be fitted with light bulldozers or
road graders, which reduce the costs of earth-moving, road-making
There will be expenditure on basic equipment in the form of axes,
saws, machetes, shovels, crowbars, and files. The number of lorries
and tractors required will depend on the size of the venture and the
availability of local transport and machinery for hire.
The source of cocoa planting-material is a matter which will be
investigated early in the proceedings, as its type will have a con-
siderable influence on the financial returns from the plantation.
Planting-material is easily transported in the form of seed, but,
with a few exceptions, uniform results cannot be expected from
selected cocoa seed at the present time. Vegetatively propagated
cocoa material gives consistent results.
Included in the plantation requirements will be seed for tem-
porary and permanent shade. If the plantation is isolated, provision
may also have to be made for seed and planting-material for food-
crops to supply the needs of labour.
The preliminary operations involved in making a cocoa plantation
will vary to some extent from country to country, and with the con-
dition of the land to be planted, depending on whether it is in high
forest or secondary bush or has been recently planted with another
High and secondary forest will have to be selectively thinned or
cleared. Where the land is already cleared, provision for ground
cover and shade must be made at an early stage.
Nurseries will be required, whether the method of planting is by
seedlings first grown in the nursery and then planted in the field,
or by direct planting of seed. In the latter case nursery plants will
be required to replace those which have weakened or died during
the first two years.
Nurseries to provide permanent shade trees and, perhaps, tem-
porary shade trees will also be required.
Subsequent operations, such as the removal of chupons or suckers,
pruning or shaping of trees, and weeding, will be necessary in most
countries. Control of temporary and permanent shade trees will
depend on how much shade is desired. Cultivation to a greater or
lesser extent, especially in the early years, is common in many
countries, but manuring is less common. Drainage may require
The need for measures of disease control at various stages differs
from country to country; in some they may be necessary at all
stages, and in others the need may be negligible.
40 The Cocoa Plantation: Establishment and Maintenance
II. PREPARATION OF THE LAND
Clearing: Complete Felling and Burning; Selective Thinning;
Partial Clearing-Sale of Timber-Sequence of Operations
-Mechanization in Felling-Planting in old Plantation Land
or Land without Forest-Prevention of Erosion-Bench-
Where the land to be planted is under forest, the preparatory treat-
ment is important. If there is a dry season of several months, the
cutting of the forest is usually done then.
COMPLETE FELLING AND BURNING
It was formerly the custom in most countries to cut down the
forest and burn the brushwood and trees, after which shade trees
Some of the immediate advantages of burning are that lining
and holing can easily be carried out, thereby saving labour at
this stage; certain nutrients are made readily available; the soil is
cleaned of certain fungi, weed seeds, and insect pests and their
sheltering places. These advantages are, however, more than offset
by the deleterious effects. Burning destroys the humus accumulated
under the forest, and the stored fertility is thus dissipated in a short
period. There is considerable opposition to burning from planters
Overhead shade can be provided by leaving a sufficient number
of deep-rooted forest trees which can create a canopy for shading the
cocoa, and which are not incompatible with its growth. It is better to
thin out the forest and leave a sufficient number of the original forest
trees as shade, rather than to cut them all out. This method allows
all the usual operations of brushing, lining, and holing to be carried
out. It has been practised in the Congo with great success. It is also
practised in West Africa to a greater or lesser extent, but not with
the same degree of skill.
When clearing the lines of trunks and brushwood, some saving in
labour can be achieved by merely making a partial clearance in the
9. Clearing jungle in Malaya for cocoa planting. A building for nursery use is in course
10. An old cocoa field cleared and lined
for re-planting. This field in Tobago is
on a very steep slope
II. Clearing secondary forest in the
Gold Coast for cocoa planting
This type of forest is dominated by the
Umbrella tree (Musanga smithii)
12. A heavy-bearing cocoa tree on
a plantation in Brazil
13. Seedlings growing in baskets
showing type of basket used and
spiral arrangement of leaves on
14. A tree grown from a rooted cutting on an estate in Trinidad. This tree is of
the clone I.C.S. 95
15. A seedling nursery at a Department of Agriculture station in the Gold Coast.
Shade is provided by tree cassava
Preparation of the Land 41
first year. If, for instance, the planting distance between rows is to
be nine feet, rows can be cleared and planted in the first year at
eighteen feet. The tree trunks and brushwood are piled in the inter-
vening space where they will settle down and rot. Incidentally, they
provide shelter for the first rows of young cocoa. A year later, the
inter-rows are cleared and planted. This method of establishing
cocoa is commonly used on the Lukolela cocoa estates in the Congo
and is considered to be economical of labour. The result is that the
odd-numbered rows are a year younger than the even-numbered
rows (or vice versa), but this is of no consequence.
It has been a common practice in some South American countries
to establish young cocoa in three- to four-foot wide rides or rentices
in the forest, the remaining trees being killed off by ring-barking or
by the use of arboricides. Under this arrangement, the proper
adjustment of shade in the early stages of the plantation's growth is
difficult. There may be too much shade at first and too little later.
SALE OF TIMBER
Clearing may be done by the use of daily labour and some or all
of the operations may be given out on contract. Where there is
timber of commercial value, it may be possible to sell it to offset
part of the clearing costs. Where the site is near a settled com-
munity, the less valuable timbers may find a sale as firewood or for
SEQUENCE OF OPERATIONS
In establishing a cocoa plantation it is possible with advantage to
vary the sequence of certain operations. In high forest much time is
gained by lining, holing, and planting temporary shade before the
major felling takes place.
Clearing of the underbrush is usually done early in the dry
season. The timing of the operations should be arranged so that
conditions are suitable for planting cocoa early in the wet season
and for its being well-established before the dry season sets in.
MECHANIZATION IN FELLING
Where the plantation is to be laid out on a large scale, and the
forest is to be completely felled as distinct from being selectively
thinned, felling by means of drawing through the forest a heavy chain
attached to two tractors will speed up the operation. Where reason-
ably efficient labour is available, however, the cost of this type of
42 The Cocoa Plantation: Establishment and Maintenance
felling would need to be carefully compared with that of felling in the
For trees up to eighteen inches in diameter, tractor-powered
winches are usually better than those which are hand-powered,
especially when the ground is soft.
PLANTING IN OLD PLANTATION LAND OR IN LAND WITHOUT FOREST
Where cocoa is to be established on land previously planted with
cocoa or another crop, and shade trees are already in existence,
most of the operations in establishing the new plantation can be done
before replacing the old shade trees. These are carefully felled later
and replaced with new trees. The necessity for establishing ground
cover and lateral shade at an early stage is as important here as
where planting is done in forest country.
If the land to be planted has few trees and little cover, then the
first consideration is to plant ground cover, lateral shade, and
permanent shade. If time and circumstances permit, the first to be
planted should probably be the permanent shade as it usually grows
more slowly than the others.
PREVENTION OF EROSION
Unless steps are taken to prevent it, erosion of the soil can take
place at all stages in the life of the plantation from the time of first
clearing the land. Erosion, in brief, means the removal by water
and wind of the humic layer and in due course a part or the whole
of the surface soil. The reduced productivity of a plantation can
often be traced to the action of erosion in one form or another. Many
years may elapse before such a plantation can be restored to a state of
Prevention of erosion in the opening stages of plantation-making
is best secured by leaving a number of forest trees in situ, or by plant-
ing permanent or temporary shade trees to protect the ground from
the effects of wind and rain. Ground cover, in the form of bananas,
tannias or other plants commonly used for this purpose, will also
prevent erosion if planted in time. The remedy in mature planta-
tions on a slope is contour drainage and the erection of earth or
other barriers to check the flow of water.
If the plantation is on a long slope liable to erosion, the cocoa
trees should be planted on the contour and tree trunks and brush-
wood piled along the contour to check the flow of water down the
slope. Brushwood and weeds piled in this way will also form an
effective barrier against a rush of water.
Preparation of the Land
Bench-terracing has long been practised on tea plantations in
Ceylon and on rubber plantations in Malaya where these are on
slopes or hillsides. Cocoa planting does not lend itself so readily to
this practice because it is necessary to preserve the surface layer, and
it is usually desirable to leave some forest trees standing, but there
are circumstances under which bench-terracing may be practicable.
It is one of the most effective measures for preventing erosion, and
is therefore worthy of consideration.
Where draining is required, the sooner it is done after the land is
sufficiently cleared the better. Cocoa may be unaffected by being
flooded for several weeks at a time by over-flowing rivers, but is
usually adversely affected by stagnant water.
The necessity for draining will be determined by a study of local
conditions. When there is a doubt, it is advisable to dig holes six
to ten feet deep in order to observe the water-level at different times
of the year. The number of drains, and their depth and width, will
depend on the lie of the land, the type of soil, and the distribution
of rainfall. The drains will naturally be made along the contour,
with sufficient fall to ensure that the water drains away gradually.
The distance between drains will be adjusted to fit in with the spacing
of the rows of cocoa trees.
On all sloping land, drains and roads should as far as possible
follow the contour. When making outlets for the drains, erosion
can be minimized by widening the outlet into a "fish-tail" shape. If
the grass at the outlet is not cutlassed too closely, it will also help to
44 The Cocoa Plantation: Establishment and Maintenance
The Site, Shading and Shelter-Planting Seed-Baskets-
Cocoa in SeedBeds-Supply and Treatment of Nursery Plants
-Nursery for Shade Trees-Nursery for Rooted Cuttings.
A nursery may be necessary because seed is not available at the
time of planting, and because it may be cheaper to grow young plants
in a nursery than to supervise them in the field. Where labour is
short a large number of plants can be supervised more carefully in
the small area of a nursery. During dry spells they are more conven-
ient for watering and they provide a supply of quick-growing plants
from which only the better-grown and more vigorous are selected.
THE SITE, SHADING AND SHELTER
The site chosen for the nursery should have a good, deep, free-
draining surface soil, within easy reach of an ample supply of water
free from objectionable minerals. A gentle slope will make drainage
easier. The nursery should be as near the fields as is practicable.
Shading can be arranged by means of bamboo uprights and cross-
pieces over which palm fronds are laid, or a more permanent struc-
ture can be made with timber scantling and wooden slats. The aim
will be eventually to allow about 50 per cent sunlight to penetrate
to the young plants for a great part of their time in the nursery.
Palm fronds used as overhead covering have the advantage that as
they wither with age they become more pervious to light, thus
providing automatically the conditions for hardening the young
plants in preparation for planting out.
A sheltered site in the forest will not need lateral shade, but where
the forest is not available lateral shade can be provided by planting
stakes of some quick-growing tree, such as Gliricidia, which grows
quickly from long cuttings pushed into the ground. The lateral
shade will, of course, be planted several months before the cocoa is
planted in the nursery, and it will require cutting back, so that maxi-
mum shade is provided in the dry season.
Where a more permanent nursery is required, a structure made
with timbers which have been treated to resist termite attack may
be erected. A series of lean-to roofs made with wooden slats so as
to admit the right amount of light will be satisfactory and will
prevent most of the rain and dew from falling on the cocoa plants.
There is often a tendency to confine nurseries, especially the larger
ones, within too small a space. As most of the transport nowadays
is by lorry, sufficient room should be left between different units of
the nursery to allow easy passage.
The seed to be planted is usually rubbed with sand or wood-ash
to remove the mucilage, but this is not necessary. It is better to
plant seeds hilum or scar-end downwards, although they can be
planted on their sides. Any other way of planting results in a dis-
torted plant. Good seed should give eighty per cent germination.
Seedlings in baskets have the great advantage that when they are
being planted out their roots are not disturbed and they develop in
a good soil. The basketed plants are easily handled and transported,
and are less liable to damage than where baskets are not used.
The lightest and most durable baskets are made from split cane.
Bamboo pots can be used but they may restrict root development
and must be removed before planting in the field.
The size of the cane basket is a matter on which opinions vary.
Large baskets require more soil or compost to fill them and are
heavy to carry. The size will depend to some extent on the size of
plant aimed at for planting. Where cocoa is difficult to establish, a
larger basket is to be preferred. The Dutch in Java favoured a
basket 18 in. to 24 in. deep by about 7 in. wide. The Gold Coast
Department of Agriculture recommends baskets which are 8 in.
deep, 7 in. wide at the top and 5 in. wide at the bottom. The base
of the basket should not be completely woven but should be left as
open as possible, with only a few strands across it to retain the soil.
This gives the tap-root complete freedom to develop. Cheap baskets
can be made by a simple weaving of palm fronds, but will not last
long or stand much handling, and are liable to disintegrate before
they reach the planting site.
When a great number of baskets is required a contract is usually
given to village communities. If baskets have to be made by labour
on daily pay they may prove to be an expensive item.
The baskets are filled with good surface soil and some sub-soil,
reinforced with compost, leaf mould, or farmyard or artificial
manure, unless the original soil is rich. Surface soil alone may be
unduly alkaline. They will be renewed from time to time if they have
deteriorated, or if the tap-root of the seedling outgrows the original
basket. When renewal is necessary, the plant along with its soil is
transferred to the new basket and fresh soil packed around it.
46 The Cocoa Plantation: Establishment and Maintenance
COCOA IN SEED BEDS
Where the cocoa seed is to be planted in beds these must be pre-
pared with care. The best available soil should be well worked and
mixed with pen manure or decayed vegetable matter and put in a
bed slightly raised from the ground. The beds should be divided
by paths and made narrow enough to permit of attention to the
plants from the paths. When the beds have been slightly consolidated
the seeds are pressed into the soil and spaced sufficiently wide apart
to allow of being removed by a trowel when ready for transplanting.
SUPPLY AND TREATMENT OF NURSERY PLANTS
Whichever method of raising plants in the nursery is adopted, it
is necessary to have a constant supply of healthy, vigorous seedlings
to replace casualties in the field during the first 24 to 30 months.
Watering in the dry season can be delayed as long as is consistent
with the good growth of the young plants, as once begun it will have
to be continued.
Losses will be reduced if the cocoa plants are subjected to a
process of hardening in the nursery, by gradually reducing the shade
to a minimum before they are transferred to the field. Many of the
losses in the field are due to damage to the tap-root of the young
cocoa plant during transplanting.
NURSERY FOR SHADE TREES
Where shade trees are to be planted as seedlings and not as seed
at stake, a nursery for these will be required. The care with which
they are raised and planted will vary with the type of trees.
NURSERY FOR ROOTED CUTTINGS
Where the size of the plantation or estate justifies the raising of its
own supply of rooted cuttings it is better to do so than to buy them
or than to obtain a free supply from a central nursery. A careful
selection of material for planting is thus possible. Recent experience
in Trinidad shows that where the large central nurseries send supplies
to plantations it is impossible to provide clonal plants which are all
up to the standard desired by the discerning planter. 0
Preparation for Planting
IV. PREPARATION FOR PLANTING
Spacing: Close v. Wide-Optimum Spacing; Close Spacing;
Thinning; Practice in Different Countries; Spacing of Shade
Trees-Lining: Lining before General Felling; Lining on the
Contour-Holing: Treatment of the Soil; Experience in the
CLOSE v. WIDE
Spacing, like shading, has given rise to a good deal of contro-
versy. The spacing distances for cocoa vary a good deal from
country to country.
Professor Hardy holds the view that the main factor affecting
spacing is the root-room in the soil, and that the feeding roots of the
cocoa tree will explore the top layer of a soil which has a good crumb
structure. As the depth of a good crumb structure varies consider-
ably, so also does the root-room. Where the crumb structure is
shallow, planting distances will be greater than where it is deep. In
other words, a good soil permits of closer spacing thandoes a poor
soil. This view is shared by Carl de Verteuil of Trinidad.
On the other hand, De Blank, of Huileries du Congo Beige, who
has wide experience of tree plantation crops in the tropics, considers
that where soils provide less good growing conditions closer spacing
is indicated. His theory of productivity is based on the estimated
potential production per unit of surface area, which can be deter-
mined by multiplying the average individual production by the
number of plants on a given area. The optimum density is a function
of three factors:
(a) The variety to be planted.
(b) The potential production of individual trees.
(c) The soil and climatic conditions under which the crop is to be
Fashions and practice in spacing have varied from country to
country and within countries. Optimum spacing of cocoa is that
which gives the greatest yield per unit of land over a given period.
Experience so far seems to show that close spacing gives a greater
yield in the early years, but where a close and a wider spacing have
been compared over a number of years, the yield per acre per
annum eventually becomes approximately the same. Close spacing
in the early years, with thinning-out as the trees develop, has been
48 The Cocoa Plantation: Establishment and Maintenance
advocated as the best means of getting maximum yields over a long
period. Planting by the triangular or quincuncial method at close
spacing lends itself more conveniently to thinning at a later stage
than where the trees are planted on the square. As long as the trees
are in reasonably straight lines which are equidistant from each other,
the fact that the trees within the lines may not always be the same
distance from each other is of less importance.
Close spacing has the advantages that the canopy of the cocoa
trees soon meets and shades the ground, thereby suppressing weeds,
and that if one tree dies the canopy of the adjacent trees soon closes
up and covers the intervening space. In West Africa the quick
closing of the canopy discourages capsid attack. There is also less
tendency for the plant to develop chupons or suckers.
A spacing of 10 ft. by 10 ft. will control weed growth when there
is fairly rapid development of the trees. Some consider that there
should be a distance of twelve feet between cocoa rows to allow of
easy access to the plantation. Whereas in the early years of bearing
close spacing makes for higher returns and less expense in weeding,
the outlay in plants is greater if selected material is being bought or
produced at high cost. This is a point to be borne in mind when
close planting is done with the intention of thinning later to provide
Where cocoa is planted at close spacing and is to be thinned after
seven or eight years, it may be planted 9 ft. by 9 ft. by the triangular
or quincuncial method. The first thinning could be done to give a
space of just over twelve feet between rows. There is a natural
tendency to postpone thinning when a good yield is being obtained
from the plantation. If it is unduly delayed, the general shape of the
trees is affected and several years may elapse before a desirable
form is attained. The time when thinning should take place must
be a matter for the good judgment of the planter. When it comes to
thinning the plants in the rows, a certain amount of selection may be
done. Two good vigorous plants may be left growing close together
and weaker plants on either side removed, provided that the gaps
left are not too wide.
PRACTICE IN DIFFERENT COUNTRIES
In the past Trinidad favoured 12 ft. by 12 ft.; Ceylon, New
Guinea and Samoa spaced at 15 ft. by 15 ft. and sometimes 16 feet
I. HEAL I Y COCOA TREE IN BEARING : The pods are of Amelonado type.
II. TYPES OF COCOA PODS : (Left to right) Two yellow Angoleta, red Amelonado,
orange Calabacillo, and two Criollo types.
III. VEGETATIVE PROPAGATION : A stem-cutting prepared for the rooting bin. The
upper surface of the stem has begun to turn brown.
IV. VEGETATIVE PROPAGATION : Underside of cutting shown in Plate III. This is a
light shade of green with no browning on the stem
V. TEMPORARY SHADE FOR YOUNG COCOA: Young clonal trees growing
under the temporary shade of bananas.
VI. YOUNG COCOA PLANTATION : Clonal trees growing under Immortelle shade.
(River Estate, Trinidad.)
VII. EFFECT OF SHADE : These two-and-a-half-year-old trees form
part of an experiment in shading and fertilizing in Trinidad. The small
tree has grown without shade. Those in the background were shaded
until two years old, when the shade was removed.
VIII. DRYING COCOA : A drying shed with movable roof, typical of plantation
equipment in Trinidad. The shed on the right holds the sweat-boxes.
4 IX. SECTIONS OF COCOA BEANS
S AFTER PREPARATION FOR THE MARKET
(1) Unfermented or slaty bean ; compare
with (5) a fully-fermented bean of good
chocolate-brown colour. (2), (3), (4)
Underfermented or purple beans. The
bright colour and cheesy cut of these beans
indicate that they are little better than
unfermented beans. (6) and (7). These
purple beans are also insufficiently fer-
mented, although they have been better
prepared than those on the left.
A sample of well-fermented cocoa should not contain
any beans of the type on the left, and should consist
of a high proportion-preferably 100 per cent-of
fully-fermented beans like No. 5.
X. COCOA GROWING UNDER FOREST SHADE IN THE GOLD COAST : The
cocoa trees are in the centre and background of the photograph.
Preparation for Planting 49
apart; the Belgian Congo for some years used a spacing of 4 metres
by 4 metres, but more recently 3 metres by 3 metres (about 10 ft. by
10 ft.) has been adopted. In experiments in Nigeria where spacings
of 8 ft. by 8 ft., 12 ft. by 12 ft., and 15 ft. by 15 ft. were tested on
different soils, the best yields were obtained in the early years at
close spacing on good soils. The West African peasant farmer,
when planting cocoa seed through his food farm, plants closely
(31 ft. to 4 ft. apart), but more recently spacing of 5 ft. by 5 ft.
is being adopted. Such cocoa farms are thinned out by the deliberate
action of the farmer and some trees are killed off by pests and
diseases, but the final stand is usually very close-spaced when
compared with the standards in other countries.
Attention must be given to the matter of filling the land to capa-
city, while making provision for the labourers to walk between the
lines with dusting and spraying equipment.
SPACING OF SHADE TREES
The shade trees will normally be planted in line with the cocoa
trees, and the spacing will depend on the size which it is expected
they will eventually attain and on the nature of their canopy.
Erythrinas in Trinidad were sometimes planted at 24 ft. by 24 ft.
and later thinned out to 48 ft. by 48 ft., or at 15 ft. by 15 ft. and
thinned to 30 ft. by 30 ft. The latter spacings were intended to allow
the trees to grow to full stature. Where control of the growth of the
shade tree by topping and cutting back the branches is envisaged a
closer final spacing would be adopted. Bananas and plantains are
usually planted at 12 ft. by 12 ft. in the rows of cocoa.
Lining is necessary in order to place the trees in such a way that
the maximum use is made of the available space, and so that the
lines of trees are eventually placed as nearly equidistant as is prac-
ticable. It is usual to work from a base line which may be across the
field or along one side and the lines will generally be orientated in a
north and south direction.
LINING BEFORE GENERAL FELLING
If before general felling in forest country it is desired to plant
lateral shade and/or permanent shade, or even cocoa itself, lining
can be done immediately the underbrush has been cleared.
The siting of the trees may be such that every four form a square
or every three form an equilateral triangle. The latter method is
50 The Cocoa Plantation: Establishment and Maintenance
more economical of space and allows of more trees being planted
per acre. When stakes are placed to mark the sites for cocoa trees,
other stakes will be inserted to mark the position of permanent
LINING ON THE CONTOUR
On hilly land it is most desirable to line on the contour. This will
enable soil conservation measures to be applied more easily, and if
the distance between the contour rows is twelve feet or more other
operations will be made easier. This distance will permit of the
mechanization of certain operations.
Holing is designed to provide suitable conditions in which the
plant may develop a root-system and establish itself.
In an easily worked fertile soil there is less need for a large hole
than in a stiffer soil. Where the soil is heavy the fork is better for
digging than the spade, as the latter tends to make the sides of the
hole impervious to water. It is more important that the hole should
be wide than that it should be deep, because the feeding roots
spread outwards, and the tap-root will in any case penetrate a
long way below the bottom of the hole. A diameter of two feet
or more with a depth of twelve to eighteen inches is a convenient
size. Where rocks or large boulders are present, it is well to probe
the bottom of the hole for a foot or more with a sharpened iron
to ensure that there is none underneath. A similar precaution should
be taken where there is the possibility of hardpan or an impervious
Where the plants are grown in baskets, the necessity for a large
hole is not so great as when they are being transferred from nursery
beds. If the seed is to be planted in the field, a good-sized hole
should be made and great care taken to fill it with a soil mixture in
which the plant can grow.
TREATMENT OF THE SOIL
It is convenient when holing to keep the surface- and sub-soils
separate. The holes should be filled with a friable mixture of a good
deal of surface soil and some sub-soil. Surface soil alone may be
too alkaline. For the same reason a concentration of wood ash is
to be avoided. When it is desired to reinforce the mixture well-rotted
compost or manure is added. If the soil is piled up in a mound over
the hole it settles down to ground level. On the other hand, a
Preparation for Planting 51
saucer effect around the plant, due to insufficient soil in the hole to
begin with or to the soil having been scraped away in the course of
weeding, may give rise to waterlogging.
The soil around the hole should be well hoed before the plants are
inserted as the feeding roots develop most quickly when the soil has
been opened up by cultivation.
EXPERIENCE IN THE GOLD COAST
Although much of what has been described here may be con-
sidered as orthodox practice and represents that adopted by success-
ful planters in the West Indies and the Americas, experience in the
Gold Coast does not completely support this. Here it has been found
that, when seed is planted "at stake," i.e. directly in the plantation,
the less the soil is disturbed after cleaning and brushing the better.
Deep cultivation tends to retard rather than accelerate the progress
of the plant.
There is some doubt here whether there is any advantage in
making holes before planting seed at stake, and good results have
been obtained without holing. The best results follow the opening
of holes immediately before planting, and not when they have been
made some time in advance and left to "weather," which is recom-
mended as good practice in other countries. When cocoa seedlings
have been planted out in baskets they have grown better when a
hole is made of just sufficient size to receive the basket and the soil
surface is not otherwise disturbed.
World Crops (March and June 1951).
Hardy, F. "Soil and soil-types suitable for the hybridization of cacao
and the improvement of cacao soils by manuring." Cocoa Research
Conference (London, 1945).
Hardy, F., "Some soil relations of the root-system of cacao." Trop.
Agric., 21, 184 (1944).
Freeman, W. G. "Results of cacao research at River Estate, Trinidad."
Trop. Agric., 6, 127 (1929).
West, J. "The development of cacao selection in Nigeria." Cocoa
Research Conference (London, 1945).
THE COCOA PLANTATION (2)
VEGETATIVE PROPAGATION OF COCOA BY ROOTED
CUTTINGS, WITH NOTES ON SOME OTHER METHODS
History of the Development of Rooted Cocoa Cuttings-
The Nursery-Collecting Cuttings-Preparing the Cuttings
-Propagators-Preparation of Rooting-bin-Striking, or
First Stage in producing Roots on the Cuttings-Conditions
inside the Propagator-Hardening-Rooting in Open Beds
under Mist Spray-Use of Greenhouses and Humidifiers-
Storage of Potted Plants-Review of Propagation Methods
-Labour Requirements-Other Methods of Propagation.
IT is well known that cocoa seedlings do not usually reproduce the
characteristics of the parent trees, whereas plants derived from
vegetatively propagated material consistently do so.
The method of vegetative propagation of cocoa most widely
adopted in recent years for large-scale multiplication (both for experi-
mental work and for planting on estates) is that of rooted cuttings.
HISTORY OF THE DEVELOPMENT OF ROOTED COCOA CUTTINGS
The results of the selection of material from high-yielding trees on
estates in Trinidad indicated the need for a rapid means of multiply-
ing the selected trees in order to provide the necessary plants for
Pyke evolved a method for the propagation of cocoa from semi-
hardwood cuttings, and this initial work was carried further by
Cheesman and Spencer, aided by the use of root-inducing hormones.
Posnette used this system for cocoa propagation at Tafo in the
The Trinidad Cocoa Board installed a propagating centre at La
Pastora during the last war for the purpose of putting superior cocoa
material at the disposal of planters. At that stage large-scale produc-
tion of rooted cuttings demonstrated that heavy losses were incurred
by the methods employed, and it was obvious that further research
work must be done if satisfactory multiplication on a commercial
scale was to be achieved.
In 1949, Dr. Harry Evans joined the Botanical Section of the Cocoa
Research Scheme as Senior Plant Pathologist. His research work
resulted in spectacular improvements in the methods of rooted-
cutting production. Most of this chapter is based on his published
and unpublished work.
The process of producing rooted cuttings entails the use of a
nursery of selected plants from which the supply of cuttings or plant
material is to be derived. The cuttings, after being treated with a
root-inducing hormone, are placed in propagating-bins or beds
which have been filled with suitable material, such as sawdust, coco-
nut fibre dust, or other rooting medium. While they are in the bins
or beds, they are kept in favourable conditions of temperature and
humidity and given the desired degree of light, and, when in due
course they develop roots, they are usually transferred to baskets
for the first stage of hardening. At this stage they have still to receive
a considerable amount of careful attention as regards watering and
regulation of light and temperature. On passing through this stage,
they are set out for the final stage of hardening and development
before planting in the field.
While the above is an outline of the procedure generally followed
at the present time, there are many variations.
It may be said that in most countries the production of rooted
cuttings calls for a considerable degree of skill and attention to detail.
Nevertheless, it is no longer regarded as something that can only be
done by the scientist. Many planters and plantation companies are
producing rooted cuttings for their own use after a study of the
literature on the subject.
It is desirable to have the nursery of trees which supply the cuttings
conveniently near the propagators. Vigorous, healthy trees, free
from mineral deficiencies, provide the best cuttings, and so a well-
drained loamy soil, rich in organic matter, is indicated. Where the
soil is below the quality required, it has to be enriched by the supply
of compost and pen or mineral manures. A soil tending towards
acidity (pH value 5-0 to 6-0) is recommended.
Good shading arrangements are necessary to enable the nursery
plants to produce a supply of soft branches in a suitable condition for
rooting; over-exposure to sunlight may cause poor rooting results.
54 The Cocoa Plantation: Vegetative Propagation
As a general guide, 25 per cent to 50 per cent full sunlight falling on
the nursery trees will be satisfactory.
The trees used for shading the nursery plants are usually those
which grow quickly from cuttings, such as Gliricidia maculata,
Erythrina poeppigiana, and certain species of Inga, but this by no
means exhausts the list of trees which may be used. Apart from
quick growth, the main essential in a shade tree is foliage which
allows of filtered light reaching the nursery plants. Plantains and
bananas have also been used to provide shade, but are liable to be
blown down and cause damage.
Emphasis has sometimes been laid on the advantage of using
leguminous shade trees, but non-leguminous trees can be used
Shade trees have to be cut back from time to time and controlled
to give a suitable degree of shade and light. Where there is a marked
dry season, they have to be cut well back before the end of the wet
season, so that they may develop thick foliage and provide a greater
amount of shade during the dry season.
The spacing at which the shade trees will be planted will depend
on their habit of growth. Gliricidia, which is employed as nursery
shade in Trinidad, is usually planted at 10 ft. by 6 ft.
A common spacing adopted for the cocoa trees is 6 ft. by 4 ft.
The planting-holes are usually filled with surface soil, reinforced
with pen manure or compost.
The age at which the young tree will yield cuttings will depend on
its vigour and speed of growth. As it is necessary to allow the plant
to develop, not more than three cuttings may be expected in the first
year. The number of cuttings that may be expected from nursery
trees up to five years old may be of the following order: up to one
year, three cuttings; next two years, twenty to thirty cuttings, but in
the following two years a much smaller number are cut. It is usual
to replace the tree at five years old, or earlier, depending on its
Although the removal of cuttings automatically prunes the tree, it
is necessary from time to time to prune the tree back severely in order
to induce a flush of new growth. This is done at the end of the dry
season, the trees having been manured beforehand.
When the trees are subjected to repeated removal of cuttings over
a period they will require frequent applications of N.P.K. fertilizers.
An application of 1-11 lb. of fertilizer per tree per annum, supple-
mented with some pen manure, should meet requirements.
The area of the nursery will, of course, be related to the area of
plantation to be established each year. One acre of nursery planted
Collecting Cuttings 55
at 6 ft. by 4 ft. will contain about 1,800 plants. Assuming twenty
cuttings per tree per annum, and allowing for casualties at all stages,
one acre of nursery should produce enough plants to establish thirty-
six acres of cocoa which, planted 9 ft. by 9 ft. in the field, gives 540
trees per acre.
Cuttings are taken from recently matured flushes when the leaves
are fully green. They should have at least three leaves, and the stems
should be green but hard, or semi-hard. They are often referred to
as "semi-hardwood cuttings." The upper surface of the stem will
usually have turned a shade of brown at this stage but the under
surface will still be green (see colour plates III and IV). Greening of
the leaves may be delayed when the soil is deficient in certain
nutrients, and it is then better to wait until the leaves are green, even
if the other conditions of the cutting indicate that it is ready for
removal from the parent tree.
If it is desired, for the sake of economy in material, to use single-
leaf cuttings, these should be cut at an earlier stage of development
when the stem is still green on the upper surface. If two buds are
left on the semi-hard stem from which the single-leaf cutting has
been removed they will sprout quickly and give further cuttings.
This point is mentioned because buds farther down on the hard stem
are dormant and will not develop so quickly.
In general, stem-cuttings should be used as they develop more
quickly than single-leaf cuttings, being ready for planting in five to six
months. The single-leaf method is used when cuttings are in short
supply and the demand for plants is high. Single-leaf cuttings take
an extra two to three months before they are ready for planting.
Those parts of the nursery tree which have been attacked by insect
pests or fungi, or trees which show signs of serious mineral defi-
ciency, are to be avoided, as such material may give trouble in
Cuttings are removed from the tree by a cut just above a node, and
may vary in length from five to twelve inches and bear three to seven
leaves. Where there are well-defined wet and dry seasons, flushes will
grow longer in the wet season, particularly at the beginning, and not
so long in the dry season. Where it is desired to get the maximum
number of cuttings from the nursery, it may be advisable to use the
longer flushes for single-leaf cuttings during the wet season and the
shorter flushes of the dry season for stem-cuttings. As the former
take longer to develop than the latter, plants of similar size will be
available for planting in the following wet season.
56 The Cocoa Plantation: Vegetative Propagation
Normal practice in Trinidad is to take the cuttings by 8.30 to
9.30 a.m., and only on wet and humid days can they be taken
throughout the day. They are placed immediately in a bucket of
water to keep them in a moist condition and in due course they are
placed in the propagating-bins.
PREPARING THE CUTTINGS
(a) Stem-cuttings. The lower leaves are removed by a clean cut
close to the stem, leaving three to six leaves, according to the length
of the cutting. The longer leaves are cut with scissors to half or a
third, depending on the original size. Leaves up to six inches long
are left untouched. The purpose of trimming is to prevent mutual
shading, and to accommodate a greater number of cuttings in a
After the leaves have been trimmed, a small piece of the base of
the stem is cut off to provide a fresh surface, and the base of the stem
is immediately dipped in a root-inducing hormone. The hormone
mixture which has had greatest success was a naphthalene-acetic
acid and p indole-butyric acid, used as a concentrated dip. This
mixture is made up by dissolving 0-4 grams of each acid in 60 ccs.
of 95 per cent alcohol and adding 40 ccs. of water.
(b) Single-leaf cuttings. Single-leaf cuttings are not taken, as such,
from the tree, but cuttings of a similar size to stem-cuttings are taken
and later divided into single-leaf cuttings.
In preparing the single-leaf cutting for the propagator, the ter-
minal bud is removed and the shoot is divided by cutting the stem
about i-inch above each node. The leaves are cut back as for stem-
The hormone described above for stem-cuttings is diluted with
50 per cent alcohol to reduce it to half-strength for single-leaf
In the case of both types of cuttings, where infection with fungi
is suspected, subsequent trouble in the propagator may be avoided
by dipping only the leaves in Bordeaux mixture before dipping the
base of the stem in the hormone mixture.
Propagating-bins may vary in size from a small single compart-
ment unit to a battery of several bins. A convenient size for a single
compartment is 4 ft. to 5 ft. long by 3 ft. wide by 2 ft. 8 in. deep.
Surface dimensions may be varied from 3 ft. by 3 ft. to 9 or 10 ft.
by 3 ft.
16. Nursery trees under Gliricidia shade, Trinidad
17. The equipment used
in preparing stem-cut-
tings: A bucket for col-
lecting cuttings, a bottle
of hormone solution, and
a dish to hold the cuttings
18. Stem- and single-leaf
cuttings trimmed and pre-
pared for the rooting-bin
'i 6-, ,
19. Propagating-bins under construction. Stones and gravel for drainage have been
placed in the bins; those in the background have also been filled with a rooting-medium.
The two types of roof over storage space can also be seen
20. A battery of rooting-bins; the glass frames are covered with a layer of cloth to
reduce light intensity; the light spray of water keeps the bins cool
21. Watering the cuttings by means of a perforated pipe installed inside the bin; here
the bins are covered with a layer of cloth
22. Effect of moisture conditions on rooting
(a) Over-watering and inadequate aeration: callus rods developing
(b) Under-watering and excessive aeration: a basal callus pad has developed
(c) Optimum conditions: these cuttings have started to root well; the
middle photograph is an end-on view of the base of a cutting
23. Effect on leaves of abnormal conditions in rooting-bin
(a) Excessive loss of moisture due to failure to maintain a high humidity causes
patchiness which can be seen above; these patches are yellow
(b) Inadequate light intensity leads to carbo-hydrate starvation which is shown by
24. Potting rooted cuttings.
The baskets are nearly filled
with potting mixture before
cuttings are put in
25. Rooted cuttings with their first flush
(a) Stem-cutting (b) Single-leaf cutting
26. Storage space for rooted
cuttings. The floor is concreted
and the roof consists of alternate
panels of glass and corrugated
27. Storage space; the cuttings
are shaded with camouflage
28. Open spray bed with lines
of T-jets on both sides