Specificity in Plant Diseases Daniel W This Volume is a compilation Jr This Volume is a compilation of many of the especially interesting questions and biological challenges that arise in the consideration of microorganisms in general and the extremophiles in particular the main commercial activity up until that time was fairly low key work in docks and harbours we decided to plan for another in 1975 and after discussion with col leagues during the Second International Congress of Plant Pathology 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