The Monograph deals with the conception, planning, implementation, results and conclusions of the International Witches' Broom Project (IWBP), which was set up in 1985 with the aim of producing an economic management system for witches' broom disease of cocoa. The contributions of the various sponsors, and the roles played by the participating organizations and scientists are described in the introductory chapter. Chapter 2 provides a review of what was, and what was not known from published literature about the cocoa­ witches' broom pathosystem in 1989. The scope of the project and the approaches used are covered in Chapter 3, while Chapters 4 to 13 report on the field studies themselves in detail. The recent appearance of witches' broom in the important cocoa area of Bahia in Brazil is described in Chapter 14, before disease management recommendations are summarised and future prospects considered in the closing chapters. The many man-years of field research in the IWBP in a total of six countries generated much useful information which was analyzed both in the individual countries and collectively. Even with a document of this size, certain information and analyses with less direct relevance to disease management had to be omitted. It is expected that more detailed treatments of certain aspects will emerge in scientific papers, and further analyses will be undertaken.

Table of Contents:
1 Introduction to the international witches’ broom project.- Witches broom disease of cocoa — an overview.- Cocoa production in South America.- The international witches’ broom project.- Operational structure of IWBP.- Facilities and personnel involved in IWBP.- Training element of IWBP.- The experimental programme.- 2 The pathosystem.- The pathosystem in outline.- Aspects of the pathosystem.- Managing the pathosystem.- 3 The IWBP studies.- Comparative epidemiology experiment.- Gradients from isolated sources.- Comparative phytosanitation experiments: gradients in plantations.- Interpretation of results.- 4 Comparative epidemiology studies: introduction.- Methods for comparative epidemiology experiment.- Site profiles.- 5 Comparative epidemiology experiment: Brazil.- Methods.- Results and discussion.- Comparative analysis and discussion.- Conclusions.- Management implications.- 6 Comparative epidemiology study: Colombia Caldas and Llanos Orientales.- Methods.- Results and discussion.- Conclusions.- Management implications.- 7 Comparative epidemiology study: Ecuador.- Materials and methods.- Results and discussion.- Conclusions and disease management implications.- 8 Comparative epidemiology study: Grenada.- Methods.- Results and discussion.- Conclusions.- Management implications.- 9 Comparative epidemiology study: Trinidad.- Methods.- Results and discussion.- Conclusions.- Management implications.- 10 Comparative epidemiology study: Venezuela.- Materials and methods.- Results and discussion.- Conclusions.- Management implications.- 11 Comparative epidemiology of the witches’ broom pathosystem.- Climate.- Basidiocarp production.- Phenology of susceptible host tissue.- Disease dynamics.- Infection efficiency.- General discussion and conclusions.- Diseasemanagement implications.- 12 Disease gradients of Crinipellis perniciosa on cocoa seedlings.- Materials and methods.- Results and discussion.- Implications for disease management.- 13 Comparative phytosanitation studies.- Protocol methods.- Site description and results.- Summary of results of sanitation.- Implications for disease management.- 14 Witches’ broom in Bahia, Brazil.- Witches’ broom outbreak in Bahia.- Cocoa phenology and climate at Itabuna, Bahia.- Prediction of witches’ broom epidemics.- 15 Disease management: recommendations.- New plantings.- Existing plantations.- Rehabilitation.- Conclusions.- 16 Future prospects for improvements in disease management.- Phytosanitation.- Biological control.- Fungicides.- Disease resistance and breeding.- Appendix I IWBP committees.- Appendix II IWBP workshops.- Appendix III Theses published by IWBP students.- Appendix IV IWBP experimental protocols.- References.