Ecology of Root Pathogens

List of contributors Foreword Chapter 1. Fungi: Pathogen or Host Dominance in Disease 1. Introduction 1.1. Root disease symptoms 1.2. Taxonomic groups 1.3. Host and type of parasitism 1.4. Ecological relations 1.5. Pathogen-host dominance system 2. Pathogen-dominant diseases; transitory relationship 2.1. Macerative pathogens 2.2. Toxicogenic pathogens 3. Host-dominant diseases; prolonged relationship 3.1. Tissue-nonspecific pathogens 3.2. Tissue-specific pathogens 4. Control principles based on pathogen- and host-dominant diseases 5. Summary 6. References Chapter 2. Behavior of Plant Pathogenic Bacteria in Rhizosphere and Non-rhizosphere Soils 1. Introduction 2. Agrobacterium 2.1. Selective media for isolating Agrobacterium spp 2.2. Survival of A. rhizogenes 2.3. Survival of A. tumefaciens 2.4. infection 2.5. Control 3. Corynebacterium 3.1. Identification 3.2. Isolation 3.3. Survival in soil 3.4. Infection 4. Xanthomonas 4.1. Identification 4.2. Isolation 4.3. Survival of xanthomonads in soil 4.4. Survival in plant materials 4.5. Survival on roots of host plants 4.6. Survival on roots of non-host plants 5. Pseudomonas 5.1. Isolations 5.2. Identification 5.3. Survival in relation to seeds and propagative material 5.4. Survival in relation to plant residues 5.5. Survival in relation to roots 5.6. Root infections 6. Erwinia 6.1. Isolation 6.2. Survival in soil 6.3. Infection 7. Streptomyces 7.1. Infection symptoms 7.2. Isolation, identification and pathogenicity tests 7.3. Influence of environmental factors 7.4. Occurrence in virgin soil 7.5. Influence of cropping practices on disease severity and the development of scab suppressive soil 7.6. Influence of green manure on potato scab and the role of antagonists 7.7. Control 8. Discussion 9. References Chapter 3. Some Interactions of Plant Parasitic Nematodes and Higher Plants 1. Introduction 2. The effects of plant-produced stimuli on plant parasitic nematodes 2.1. Hatching 2.2. Molting 2.3. Attraction 2.4. Initiation of the feeding process 2.5. Initiation of partial or full penetration 2.6. Emergence from roots 3. The effect of the host plant on the size and composition of the associated population of plant parasitic nematodes 3.1. Techniques 3.2. Moderate stress 3.3. Sex reversal and similar phenomena 3.4. Mineral nutrition of the host 4. Some ways in which nematodes affect higher plants 4.1. Introduction 4.2. Stimulation of growth 4.3. Alterations in chemical composition 4.4. Criticisms 4.5. Mechanisms of accumulation or alteration 5. References Chapter 4. Viruses 1. Introduction 2. Morphology, classification, nomenclature, multiplication and translocation of viruses infecting plants 2.1. Morphology of viruses infecting plants 2.2. Classification and nomenclature of viruses 2.3. Infection of plants 2.4. Multiplication and translocation of viruses infecting plants 3. Symptoms of infection in roots 3.1. Location of virus in root tissue 3.2. Yield loss due to root infection 4. Release and survival of viruses in soil 4.1. Crop debris 4.2. Release of viruses into soil by living roots and the possibility of active uptake by roots 5. "Soil-borne viruses" and their biological vectors 5.1. Nematodes 5.2. Fungi 6.