Molecular diagnostics of plant diseases offer a number of advantages over traditional, highly-specific methods based on microscope examination of morphological features. Not only have molecular tools helped by increasing the efficacy, accuracy or speed of diagnosis; their common technological basis also reduces the hard-to-sustain reliance of routine testing laboratories on staff with very specialist skills. This book provides protocols for the majority of nucleic acid-based methods currently applied to plant pathogen detection and identification. These generic techniques are appropriate for use on any target with minimal modification, making this book a useful resource for students of plant pathology, diagnosticians and plant pathologists.