This book features four peer-reviewed reviews on understanding and tackling the major pests and diseases affecting forest trees. The first chapter uses a case study approach to describe how various forest pathogens affect trees and introduces strategies to reduce damage caused by forest pathogens in managed stands. The chapter introduces parasitic flowering plants, rust pathogens, diseases caused by Phytophthora spp., as well as abiotic disease. The second chapter reviews the range of pathogens in tropical forests, from root, stem and wilt diseases, to foliage pathogens, nematodes, algae and parasitic plants. The chapter also details the different approaches to disease management, including selection and breeding for resistance and biological control. The third chapter considers the interacting effects of climate change on native and invasive insect pests in boreal and temperate forests. The chapter discusses recent advances in predicting forest insect responses to climate change, as well as best practices for their monitoring and management. The final chapter provides a brief overview of Dutch elm disease, citing its emergence, modes of transmission and methods of control. A case study on the development of the Verticillium albo-atrum WCS850 strain to control the disease is then discussed in detail.