Plant-parasitic nematodes are found in all agricultural regions of the world and can cause diverse damage in plants. In doing so, they predispose their hosts to attack by other plant pathogens by acting as vectors for viruses, bacteria or fungi. Nematode interactions with root symbionts such as root nodule bacteria and mycorrhizal fungi are also significant for crop production. This book provides a comprehensive and up to date account of these interations, incorporating both the theoretical and practical aspects. Each chapter presents a review of the available literature, giving insights into current thinking, pointing out the limitations and gaps in the present knowledge and directing the way forward for future research. Separate chapters deal with the interactions of nematodes with plant viruses, plant pathogenic fungi and bacteria, nematodes, insects, root nodule bacteria and mycorrhizal fungi. Some aspects, particularly fungus-nematode interactions, have received more detailed treatment than is usually available in reviews on the topic. A chapter on the management of disease complexes summarizes the current state of knowledge and emphasizes the agricultural importance of the disease complexes and options available for control.