This book offers an in-depth exploration of phytopathogenic bacteria, nematodes, protozoa, and algae within the context of agroecology. Each chapter meticulously details the introduction, taxonomy, and diseases caused by these pathogens, alongside their pathogenic mechanisms, economic significance, and strategies for identification and control. By providing comprehensive insights into these topics, the book empowers researchers to manipulate these pathogens to suit their needs. Key concepts covered include the economic impact of plant pathogens on yield loss, the pathogenic cycles of various microbes, and effective control measures. The book's expert contributors present a thorough analysis of 104 plant pathogens, organized into distinct microbial groups. This volume is an essential resource for understanding the complex interactions between pathogens and their host plants, offering valuable knowledge for developing sustainable agricultural practices. This book is an indispensable resource for postgraduate students, research scholars, post-doctoral fellows, and educators in fields such as Plant Microbiology, Plant Pathology, Bacteriology, Protozoology, Algology, and Nematology. As the second volume in a comprehensive three-volume compendium, it provides critical insights into the economic importance of pathogens and their role in yield loss, making it a must-have for anyone involved in plant sciences.