With 160+ countries and islands, the tropical belt is the geographical region centered on the equator and limited by the tropics of Cancer and Capricorn. Tropical agricultural production is mostly for local consumption but cash crops are also present. Tropical agriculture is characterized by a significant lack of capital in research and agricultural systems and by a high prevalence of insect pests and diseases. Phytoplasma diseases are associated by bacteria-like pathogens living in plant sap and spread by sap-feeding insects. They are emerging diseases and are difficult to control, mostly because their epidemiology is not known. This book will focus on detection and prevention of phytoplasma diseases in field and horticultural crops grown in the tropical belt. The book will review current prevention methods used in small and large-scale farms, and present research results aiming at developing sustainable management of phytoplasma diseases in the tropics.