NEW PLANT-VIRUS PROBLEMS IN DEVELOPING-COUNTRIES - A COROLLARY OF AGRICULTURAL MODERNIZATION

In plant virology, viruses are mostly dealt with as useful molecular biological tools in studies of the riddle of life. However, viruses were first detected and studied as incitants of disease, and those which damage crops, continue to cause considerable concern to society as major constraints in agricultural production. The pressure for agricultural development is especially high in the developing countries, most of which are located in the tropics, where agricultural productivity lags behind rapid population increases. Traditional subsistence agriculture on small-scale holdings, with a great variety of crops often grown in mixtures, is rapidly giving way to modern agricultural practices, with genetically more homogeneous monocultures grown over large acreages. The ensuing trade and transport of produce via complex peripheral organizations further allow and stimulate personal and regional specialization in agricultural production, in turn, leading to further change. Economically, such modernization is usually interpreted in terms of usefulness. But with increasing awareness of the complexity of nature and of agroecosystems, man is becoming increasingly alert that every coin has another side and that human interference is ambivalent. Through agricultural modernization, present day crops are often more vulnerable to a wide range of pests that, according to the Food and Agricultural Organization (FAO) definition, include weeds and viruses. Most, if not all, crop diseases and pests are man-made and new problems arise as a corollary of agricultural modernization. These problems are discussed in this chapter, with special reference to viruses, which play an intricate, intriguing, and often incompletely understood role that has a high impact on human society. This chapter concentrates on the developing countries, and thus largely on the tropics, because agricultural progress is hoped to be especially rapid there and also because of the author's involvement in the activities of organizations, such as the FAO, the International Board for Plant Genetic Resources (IBPGR), and International Agricultural Research Centres (IARCs) of the Consultative Group on International Agricultural Research (CGIAR) that are committed to helping to increase crop productivity in developing parts of the world in order to alleviate food shortages and improve the living standards. © 1992, Academic Press Inc.