Wakelyns Agroforestry, Fressingfield, Suffolk IP19 5SD, UK

Background and objectives
The development of a sustainable future depends on progress in three directions: social justice for all, stability and soundness in economic systems, and sustainable use of the environment. Unfortunately, current trends in agriculture are towards further industrialization, including more crop specialization, monoculture and globalization of production and marketing, which lead to non-sustainable systems in terms of society, economics and the environment. Effects from this overall problem are evident in plant disease problems worldwide. Massive monoculture encourages many plant pathogens both in disease expression and in the development of new and undesired variation in pathogen populations. Increased intensity of crop production produces similar results. Globalization leads to widespread movement of plant pests and pathogens that cannot be restrained by the available quarantine systems. To maintain industrialized monoculture requires a massive investment in fungicide use and defensive plant breeding, together with associated activities and costs. There are many ways of dealing with these problems, whose application will need political recognition and will. Before that, however, plant pathologists need to demonstrate widely those many alternatives and their relative advantages. This is the major challenge of this symposium.

The basis of low-cost, sustainable disease control is a sound cropping system involving appropriate rotation among a diverse range of crops. In many cases, this can be sufficient to reduce diseases to levels of negligible importance. For those that remain troublesome, there is a wide range of cultural practices available, some known, some forgotten, that are covered elsewhere in this symposium. In addition, there are many possibilities, some available, some to be developed in the use of diversity within and among crops, from the simple level of variety mixtures, through to complex systems of agroforestry with diversity used at many different levels.

Results and conclusions
Systems of organic agriculture have proved remarkably robust in showing one important way forward. Many of the problems of modern, mainstream agriculture simply do not occur in organic agriculture; others that do so are usually of little environmental importance. Moreover, within organic agriculture, and particularly for small-scale, intensively managed systems, overall productivity can be higher than in mainstream production, and much higher if full environmental costings are included in system comparisons. There is strong evidence of increasing interest in such systems worldwide. As one example, Danish agriculture aims to be completely organic by 2010. However, current approaches to organic agriculture, particularly in the developed world, are still inadequate in terms of long-term sustainability, particularly in their limited use of biodiversity and in their current tendency to mimic industrial agriculture. Greater exploitation of cultural methods and of biodiversity require intensive management of appropriate farm systems to produce healthy, fresh food for immediate local consumption. Such developments need changes in political attitudes to agriculture and to farmers in terms of society, economics and environment.