Integration of breeding and technology into diversification strategies for disease control in modern agriculture

While diversity for resistance has been recognised for more than 60 years as a key factor in disease management, and diversification strategies such as cultivar mixtures and multilines are described and advocated in almost every plant pathology textbook, the general view in modern agriculture is that diversity would be too difficult and expensive to implement. In addition, difficulties in marketing the produce are emphasised. The question thus arises if and how such strategies can be designed to find a place in modern agriculture. Considering the general ecological benefits of diversification and the possible economical benefits for growers and society, several possible approaches to the solution of actual and perceived problems in modern agriculture are discussed. An important route towards achieving diversity would be to integrate it into the breeding process. Selection criteria would include inducibility of resistance and competitive ability, in order to produce diversified varieties able to adapt both to unpredictable environmental conditions (especially climatic) and to changing pest and pathogen populations through co-evolution. Evolutionary breeding methods such as composite crosses and modern landraces and some of the legal problems associated with these approaches are discussed. Technical solutions are integral to the future use of diversification strategies and range from more or less simple adjustments to machinery for planting and harvesting to devices designed for separation of the harvested products.