Our basic understanding of the molecular mechanisms controlling interactions of pathogenic and symbiotic microorganisms has advanced enormously during the last decade. This basic knowledge has created the potential for fantastic new applications in agriculture and forestry. This book is volume II in a series on plant–microbe interactions in agriculture and forestry. The topics selected for this volume are very timely since several chapters are of relevance for agricultural sustainability (e.g. plant growth promoting microorganism, biopesticides the use of SAR for plant disease management, etc.) or discuss the implications of the release of genetically modified plants and microorganisms in the environment. The chapters are in general well written and are thought provoking concerning the application in forestry and agriculture of our rapidly increasing basic knowledge of controlling mechanisms. By itself this volume does not provide a comprehensive overview of a specific area of the field of plant–microbe interaction, however, the series as a whole has the potential to provide this overview and to become an invaluable reference work for scientists working in forestry and agriculture.