Microbial Plant Pathogens Detection and Management in Seeds and Propagules

Healthy seeds and propagules are the basic requirement for producing good grains, fruits and vegetables needed for human survival and perpetuation. Dispersal of microbial plant pathogens via seeds and propagules has assumed more importance than other modes of dispersal, as infected seeds and propagules have the potential to become the primary sources of carrying pathogen inoculum for subsequent crops. Several diseases transmitted through seeds and propagules have been shown to have the potential to damage economies as a result of huge quantitative and qualitative losses in numerous crops. Hence, it is essential to rapidly detect, identify and differentiate the microbial plant pathogens present in seeds and propagules precisely and reliably, using sensitive techniques.

Microbial Plant Pathogens: Detection and Management in Seeds and Propagules provides a comprehensive resource on seed-borne and propagule-borne pathogens. Information on the biology of microbial pathogens, including genetic diversity, infection process and survival mechanisms of pathogens and epidemiology of diseases caused by them, are discussed critically and in detail to highlight weak links in the life cycles of the pathogens.
Development of effective disease management systems, based on the principles of exclusion and eradication of pathogens and immunization of crop plants to enhance the levels of resistance of cultivars to diseases, has been effective to keep the pathogens at bay. The need for production of disease-free seeds/propagules has been emphasized to prevent the carryover of the inoculum to the next crop or introduction of the pathogens to other locations. Effectiveness of adopting simple cultural practices and development of cultivars resistant to diseases through traditional breeding methods or biotechnological approach have resulted in reducing the pathogen inoculum and disease incidence. Although application of different chemicals may reduce the disease incidence effectively, biological management of crop diseases, employing potential biological control agents have to be preferred to preserve the agroecosystems. Greater efforts have to be made to integrate compatible strategies to enhance the effectiveness of diseases management systems.
Protocols appended at the end of relevant chapters form a unique feature of this book to enable the researchers to fine-tune their projects.

This 2 volume set provides comprehensive and updated information about the economically-important groups of microbial plant pathogens carried by seed and propagules. Graduate students, researchers and teachers of plant pathology, plant protection, microbiology, plant breeding and genetics, agriculture and horticulture, as well as certification and quarantine personnel will find the information presented in this book useful.

Preface xv

Acknowledgement xvii

Volume 1 Pathogen Detection and Identification 1

1 Introduction 3

1.1 Concepts and Implications of Pathogen Infection of Seeds and Propagules 3

1.2 Economic Importance of Seed] and Propagule]Borne Microbial Pathogens 4

1.3 Nature of Seed] and Propagule]Borne Microbial Pathogens 6

1.4 Development of Crop Disease Management Systems 8

References 9

2 Detection and Identification of Fungal Pathogens 12

2.1 Detection and Differentiation of Fungal Pathogens in Seeds 12

2.2 Detection and Differentiation of Fungal Pathogens in Propagules 86

2.3 Appendix 104

References 112

3 Biology of Fungal Pathogens 134

3.1 Biological Characteristics 135

3.2 Physiological Characteristics of Fungal Pathogens 144

3.3 Genotypic Characteristics of Fungal Pathogens 147

3.4 Influence of Storage Conditions 165

3.5 Appendix 166

References 166

4 Process of Infection by Fungal Pathogens 174

4.1 Invasion Paths of Seedborne Fungal Pathogens 174

4.2 Invasion Paths of Propagule]Borne Fungal Pathogens 207

References 210

5 Detection and Identification of Bacterial and Phytoplasmal Pathogens 220

5.1 Detection and Identification of Bacterial Pathogens 220

5.2 Detection of Bacterial Pathogens in Propagules 273

5.3 Detection of Phytoplasmal Pathogens 326

5.4 Appendix 343

References 352

6 Biology and Infection Process of Bacterial and Phytoplasmal Pathogens 375

6.1 Biology of Bacterial Pathogens 375

6.2 Disease Cycles of Seedborne Bacterial Pathogens 377

6.3 Disease Cycles of Propagule]Borne Bacterial Pathogens 409

6.4 Biology of Phytoplasmal Pathogens 429

6.5 Disease Cycles of Phytoplasmal Pathogens 431

6.6 Appendix 437

References 437

7 Detection and Identification of Viruses and Viroids 457

7.1 Detection of Viruses in Seeds 457

7.2 Detection of Viruses in Propagules 493

7.3 Detection of Viroids in Seeds 572

7.4 Detection of Viroids in Propagules 577

7.5 Appendix 590

References 594

8 Biology and Infection Process of Viruses and Viroids 619

8.1 Characteristics of Plant Viruses 619

8.2 Biological Properties of Viruses 620

8.3 Infection Process of Plant Viruses 632

8.4 Characteristics of Viroids 646

8.5 Infection Process of Viroids 651

References 656

Index 669

Volume 2 Epidemiology and Management of Crop Diseases 1

9 Epidemiology of Seed] and Propagule]Borne Diseases 3

9.1 Epidemiology of Fungal Diseases 4

9.2 Epidemiology of Bacterial Diseases 27

9.3 Epidemioloy of Virus Diseases 37

References 42

10 Crop Disease Management: Exclusion of Pathogens 52

10.1 Health Status of Seeds and Propagules 52

10.2 Plant Quarantines for Preventing Entry of Microbial Pathogens 63

10.3 Production of Disease]Free Seeds and Propagules 72

10.4 Appendix 89

References 91

11 Crop Disease Management: Reduction of Pathogen Inoculum 100

11.1 Reduction of Pathogen Inoculum by Cultural Practices 100

11.2 Reduction of Pathogen Inoculum by Physical Techniques 123

11.3 Reduction of Pathogen Inoculum by Chemical Techniques 132

References 133

12 Crop Disease Management: Enhancement of Genetic Resistance of Crop Plants 142

12.1 Types of Disease Resistance 142

12.2 Identfication of Sources of Resistance to Crop Diseases 145

12.3 Improvement of Disease Resistance Through Biotechnological Approaches 188

References 205

13 Crop Disease Management: Biological Management Strategies 224

13.1 Evaluation of Biotic Agents for Biological Control Potential 225

13.2 Evaluation of Abiotic Agents for Biological Control Potential 262

13.3 Methods of Application of Formulated Products of Biological Control Agents 283

13.4 Integration of Biological Control with Other Management Practices 289

References 290

14 Crop Disease Management: Chemical Application 306

14.1 Application of Fungicides 307

14.2 Application of Chemicals Against Bacterial Diseases 341

14.3 Application of Chemicals Against Virus Diseases 348

References 351

15 Crop Disease Management: Integration of Strategies 361

15.1 Development of Integrated Disease Management Systems 361

15.2 Management of Fungal Diseases 364

15.3 Management of Bacterial Diseases 369

15.4 Management of Virus Diseases 373

References 377

Index 383