Plant diseases are usually caused by fungi, bacteria and viruses. Also there are other diseases which are caused by adverse environmental conditions. Plant disease resistance protects plants from pathogens in two ways: by pre-formed structures and chemicals, and by infection-induced responses of the immune system. Relative to a susceptible plant, disease resistance is the reduction of pathogen growth on or in the plant, while the term disease tolerance describes plants that exhibit little disease damage despite substantial pathogen levels. Disease outcome is determined by the three-way interaction of the pathogen, the plant and the environmental conditions. Some of the earliest and most prominent uses of genetic modification technology in crops have related to disease management. The insertion of a Bacillus thuringiensis gene into crops such as corn resulted in protection against damage caused by certain insects, eliminating the need for pesticides against those particular pests is one example. Another example, the ability of crops to thrive despite the application of glyphosate, was brought about by modifying crops so that the pathway affected by the chemical to cause plant death is cycled more regularly, helping the crop to survive. The book provides thorough information about bacteria and bacterial plant diseases. It covers history, structure, classification, special DNA characteristics and special activities of bacteria. The book fulfil not only the need of the students to find literature on the diseases and other pathological conditions difficult to obtain and access, but also provide complete systematic treatment of the subject from their point of view.