Part A and Part B of the fifth of twelve volumes of The Mycota deal with the mechanisms of interactions between fungi and plants and consider pathogenic as well as mutualistic associations. Nobody involved in the manipulation of plant populations can afford to ignore the fungi, so pervasive and important are fungus/plant interactions for the well-being of plant communities, both managed and natural. Consequently, these volumes will be of interest to a broad range of professionals involved in agriculture, forestry, horticulture, and conservation as well as plant pathology, mycology, ecology, and evolution.