This book offers an in-depth exploration of phytopathogenic viruses and viroids 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. The chapters investigate key concepts such as pathogen taxonomy, disease cycles, and control measures, addressing critical questions about their economic impact on crop yield. 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 practical solutions for disease management. This book is an invaluable resource for postgraduate students, research scholars, post-doctoral fellows, and educators across disciplines such as Plant Microbiology, Plant Pathology, Entomology, Virology, and Nematology. As the second volume in a comprehensive three-part series, it provides crucial insights into the economic importance of bacteria, fungi, viruses, viroids, and nematodes. This compendium is a must-have for anyone seeking to deepen their understanding of plant pathogens and their impact on agriculture.