Plant diseases are caused by different groups of organisms belonging to fungi, bacteria, viruses, phytoplasmas etc. They cause drastic yield losses in agricultural crops and therefore, need to be identified in the early stages and thereby, management strategies can be adopted accordingly. In this book, it is focused majorly on some of fundamental aspects like isolation and identification of different fungal genera with their morphological characters and microscopic features, methods of isolation of nematophagous fungi and various preservative methods. Features ·Role of tissue culture in developing disease resistance plants and development of transgenics against viral and fungal diseases has been discussed. · As far as Virology is concerned, different molecular techniques like PCR, AFLP, Multiplex PCR etc., for detection of multiple infections along with procedures are given. ·Application of nanotechnology in niche areas of Plant Pathology are described briefly.