Book reviews 235

There is a good, concise account, supported by reference to no less than 191 publications, of those diseases considered to be of economic importance. However, these do not include Armillaria root rot, which is serious in Africa, nor two maladies which are of some importance in Malaysia, namely mouldy rot (Ceratocystis fimbriata) and birds eye leafspot (Helminthosporium heveae). Pests, which are usually of little importance in rubber, are briefly covered in the following chapter.

The 'agricultural' content of the book is completed by the last three chapters which deal with the properties and uses of rubber wood, ancillary sources of income such as rubber seeds and rubber honey (sic.), and with guayule.

Chapters 17-22 are concerned with rubber technology. There is a good summary of the techniques of primary processing into latex concentrate, sheets, crepes and technically specified block rubbers, followed by an account of the physical and technological properties of raw and vulcanised rubber and a description of modern vulcanisation systems. Chapter 20 deals with the technology and chemistry of the modification of natural rubber to give it special properties, including epoxidation and the production of graft polymers and blends, while thermoplastic natural rubber also has a chapter on its own. There is a concise account of the engineering properties and applications of natural rubber.

The inclusion of this well-conceived section on rubber technology probably justified the publisher's claim that 'no other book on natural rubber covers such a broad spectrum of subjects.' However, it is likely that readers will be predominantly interested either in rubber technology or in the agro-biological studies, and there may be books that deal more comprehensively with one or the other of these areas. Be this as it may, the book certainly provides authoritative and generally up-to-date reviews of all the more important scientific areas of natural rubber research and development, well supported by lengthy reference lists. It should prove a very useful reference book for scientists interested in these, and similar, fields. A complaint may be made about the paucity of illustrations; there are only a few line diagrams and black and white photographs, most of the latter being poorly reproduced.

C. C. Webster

Tropical Forests and their Crops. N. J. H. Smith, J. T. Williams, D. L. Plucknett and J. P. Talbot, Comstock Publishing Associates, Ithaca and London, 1992. 568 pp. Price: US$ 27.95 (paperback). ISBN 0-8014-2771- 1 (cloth), 0-8014-8054-2 (paper)

236 Book reviews

At 568 pages, well-written and illustrated, this book is excellent value, but the title is somewhat misleading. Were it published in the eighteenth century, it might appropriately be called 'An account of the genetic resources of well-known, and some lesser-known, beverages, fruit, food, and other productive crops which originated in tropical forests, together with their origins and uses; accompanied by a plea for the conservation of forests and thereby of this genetic resource base; and including a monograph on avocado, drawn from the most recent sources.' Today, we should probably settle for 'Genetic resources of tropical tree crops.'

An excellent short introductory note enables the non-specialist to 'get by in genetics'. The first chapter is a short account of tropical forests in general, with emphasis on biodiversity and gene pools. We then go into the meat of the book--nine chapters on beverage crops, major fruits, regional fruits, rubber, oils and resins, carbohydrate fruit crops, fuel- wood/fodder crops and bamboos, spices and nuts--33 crops, or related groups of crops. Whilst general information on origins and uses (but not agronomy) is given, the core of these accounts is the gene pool, breeding challenges, and prospects. An appendix lists basic information on over 200 more species. Presumably as the research subject of one of the authors, there is a 60-page account of the avocado (Persea americana).

The final chapters cover conservation of germplasm, both ex situ (germplasm collections, tissue cultures, field gene banks) and in situ (conserving forests that hold the wild relatives of cultivated plants). Among the special reasons for the latter is the possibility of finding genetic material from which to develop strains resistant to the devastat- ing pests and diseases which from time to time attack our specialised and delicate cultivars. The world institutions for collecting, maintaining, and breeding each crop are listed.

Whilst no genetic expert, I am confident that this book is scientifically sound, indeed, authoritative. Despite there being four authors, there are no breaks of style. Indeed, it is an example to other writers of how a technical subject can be made not merely readable but interesting, holding the attention where one dips into it. Photographs of the plants, and of people collecting, eating or selling them (and for the special topic, 'Wilson Popenoe, 29-year old avocado explorer, in Ecuador, 1921'), add to the interest.

There are omissions, or a selection bias. We have coffee, cacao and cupua~u (Theobroma grandiflorum), but not tea, presumably on the grounds that it did not originate in the forest. The author know most about Latin American forests and crops, are sound on Asia, but are less familiar with Africa. It is rightly pointed out that many fruits now eaten regionally might be commercialised (this reviewer votes for rambutan,

Book rev#ws 237

Nephilium lappaceum); but no mention is made, for example, of the many Nigerian fruits identified for this purpose.

To foresters, of course, the most important 'crop' of tropical forests is timber, but there are other excellent books on this. Two tropical pines are included with respect to their resins. Agroforestry systems, which are excellently suited to cultivation of these kinds of plants, are noted with respect to 12 crops. The most serious fault is to have a chapter on 'fuel- wood and fodder (crops)' which is confined to a short account of Leucaena ssp. Many of the large number of multipurpose trees used in agroforestry originate in forests, often as fast-growing understorey species.

These are minor criticisms on an authoritative and clearly-written guide to the genetic resources of tropical tree crops, which should find a place in all libraries and, thanks to its prices, on many private book- shelves.

Anthony Young

Books Received

But Not Reviewed, To 31 October, 1993

Trends in Agricultural Diversification: Regional Perspectives. Edited by S. Barghouti, L. Garbus and D. Umali. World Bank Technical Paper Number 180, 1992.

Indigenous Integrated Farming Systems in the Sahel. M. Speirs and O. Olsen. World Bank Technical Paper Number 179, 1992.

Common Property Resources: A Missing Dimension of Development Strategies. N. S. Jodha. World Bank Discussion Paper 169, 1992.

Poverty Alleviation through Agricultural Projects. E. D.'Silva and K. Bysouth. EDI Policy Seminar Report No. 30, The World Bank, 1992.

Rural Infrastructure, the Settlement System, and Development of the Regional Economy in Southern India. S. Wanmali. IFPRI Research Report No. 91, 1992.

Tropical Acacias in East Asia and the Pacific. K. Awang and D. A. Taylor. Winrock International Institute for Agricultural Research, 1992.

Research on Farmers' Objectives for Tree Breeding. Edited by J. B. Raintree and D. A. Taylor. Winrock International Institute for Agricul- tural Research, 1992.