Morphological, biological, biochemical and physiological characteristics have been used for the detection, identification and differentiation of fungal pathogens up to species level. Tests based on biological characteristics are less consistent. Immunoassays have been shown to be effective in detecting fungal pathogens present in plants and environmental samples. Development of monoclonal antibody technology has greatly enhanced the sensitivity and specificity of detection, identification and differentiation of fungal species and varieties/strains. Nucleic acid-based techniques involving hybridization with or amplification of unique DNA have provided results rapidly and reliably. Presentation of a large number of prools is a unique feature of this volume.