This book is an outcome of research, aims to help better understanding of the problems associated with trees in parks and roadsides. It outlines the diseases cause by fungi. Chapter I introduces trees and their importance in parks and roadsides, heart rot and root rot fungi, types of wood decaying fungi, Signs and symptoms of diseases and their geographical description of some location in the studied areas. Chapter II reviews the literature including taxonomy of Ganoderma and Phellinus. Chapter III deals with surveys, collections, identification of pathogens, and analysis of damage to the infected plants due to the diseases. Chapter IV is devoted to the Description of park and roadside tree diseases, estimation of the infected trees population and losses, Description of Ganoderma and Phellinus, preparation of the identification keys of species from the genus Ganoderma and Phellinus. Chapters V and VI are dedicated to the discussion and prominentfeatures including conclusions, record of new species of Ganoderma & Phellinus, and attempts to give possible recommendations to control the diseases and prevent further decay and death of thepresent plant flora in the studied areas.