A NATO Advanced Study Institute on "Phytotoxins in Plant Diseases" was held in Pugnochiuso (Italy) in June 1970. It was concerned mainly with the chemistry and mode of action of substances toxic to higher plants which are produced by pathogenic bacteria and fungi. The role of such substances in specificity was consider ed but largely in relation to host-specific toxins. In 1973, in light of the success of the 1970 Institute, we decided to plan for another in 1975 and after discussion with col leagues during the Second International Congress of Plant Pathology, we selected "Specificity in Plant Diseases" as the theme for the 1975 Institute. Our chief reasons for the choice were that specificity is un doubtedly the dominant problem in plant pathology and that with the rapid increase during the last decade or so in the diversity and sophistication of biochemical techniques, we should now expect during the next few years much more research on specificity and major ad vances in our understanding of the mechanisms that control it. It seemed to us that a residential meeting with the advantages and status of a NATO Advanced Study Institute would do much to stimulate interest and research in this most important field. The theme also had the merit of continuity with that of the 1970 Institute.

Inhalt
Opening Address.- The Phenomenon of Specificity in Plant Disease.- Tissue and Organ Specificity in Plant Diseases.- Genetics of Host-Parasite Interactions.- Gene Functions in Host-Parasite Systems.- Cell Surface Membranes of Animal Cells as the Sites of Recognition of Infectious Agents and Other Substances.- Cell Surfaces and the Biochemistry of Varietal Specific Pathogenesis.- Models of Interaction between Higher Plants and Bacteria.- Reactions of Cytoplasm and Organelles in Relation to Host-Parasite Specificity.- Specific Interactions Involving Hormonal and Other Changes.- Effects of Structure of Active Compounds on Biological Activity and Specificity.- Evidence for Direct Involvement of Nucleic Acids in Host-Parasite Specificity.- Protein Specificity in Plant Disease Development: Protein Sharing between Host and Parasite.- The Role of Phytotoxins in Specificity.- Role of Preformed Factors in Specificity.- Phytoalexins and the Specificity of Plant-Parasite Interaction.- Induction of Hypersensitive Responses to Fungal Pathogens.- Induction and Suppression of the Hypersensitive Reaction Caused by Phytopathogenic Bacteria: Specific and Nonspecific Components.- Specific Interactions in Higher Plants.- Specificity An Assessment.- Participants.