Diseases in plants are caused by either non-living environmental factors or living agents. Plant diseases may also be grouped based on the causal agent involved, the plant part affected or the type of symptoms. Understanding the disease cycle is important when considering control options. Learning the chain of events that contribute to a disease helps point out the weakest links. Control measures can then be used to break the cycle. Most pathogens must survive an adverse period, usually winter, when they do not actively incite plant diseases. This overwintering inoculum reinfects or continues infecting the plant host in the spring. Some diseases are characterized by a single cycle during the year. Other diseases continually produce new inoculum, repeating the cycle many times during the course of a single growing season. The five basic principles of plant disease control are: exclusion, avoidance, eradication, protection, and resistance. These principles work at federal, state, county, and personal levels. This book describes the most effective ways of preventing plant diseases in simple and lucid manner. We home that the students of agriculture, plant pathologists and farmers who intend to get a preliminary idea of the subject will find this book useful.