Plants possess a rather complex and efficient immune system. During their evolutionary history, plants have developed various defense strategies in order to recognize and distinguishing between self and non-self, and face pathogens and animal pests. Accordingly, to study the plant innate immunity represents a new frontier in the plant pathology and crop protection fields. This book is structured in 6 sections. The first part introduces some basic and general aspects of the plant innate immunity and crop protection. Sections 2–5 focus on fungal and oomycete diseases (section 2), bacterial and phytoplasma diseases (section 3), virus diseases (section 4), and insect pests (section 5), with a number of case studies and plant–pathogen/pest interactions. The last section deals with plant disease detection and control. The book aims to highlight new trends in these relevant areas of plant sciences, providing a global perspective that is useful for future and innovative ideas.