Preface

The science of plant diseases (plant pathology or phytopathology) has become like a child of needfulness. Plant diseases have caused concern throughout history since the first crop plants were domesticated during the transition to agriculture between 2,000 to 12,000 years B.C. The first record of plant disease symptoms was found in Vedas (Rugveda, Athavaeda) as early as 1,200 B.C. Control of a disease was mentioned in "VRIKSHAYURVED" by Surapal in ancient India. Mention of plant disease has been made in Buddhist literature in 500 B.C. The Greek philosopher Aristotle wrote about plant diseases in 350 B.C. Theophrastus also wrote about cereal disease and even suggested some remedies to control them (in 300 B.C). In the Medieval Ages, the writings of the Arabian Ibn-al-Awam (10th Century, Seville, Spain) described symptoms and control measures for some plant diseases. There are references in the Old Testament of the Bible to blights, blasts, and mildews (6th century B.C.). Following the above-mentioned references, we can begin to understand that with domestication of crop species, their pathogens have also developed.

Since ancient times, plant pathogens, as the causal agents of plant diseases, have challenged farmers because agriculture was crucial in supporting growing human populations. The need for the study of plant pathogens gave rise to the development of new sciences, new technologies for plant breeding, and the agrochemical industry for pesticide development. Yet, all our actions and efforts to suppress or eradicate these diseases has constantly pressured these various organisms to evolve and adapt for survival. This ability is a natural phenomenon or evolution. For the pathogens in modern agro-ecosystems, the selection pressures are provided by human. Pathogens constantly find new ways to adapt to conditions that humans create and keep existing. Is it possible that with the cultivation of plants, we have also cultivated pathogens?

Plant diseases today are diseases of high standards because all agricultural techniques and pest management methods implemented in modern agricultural crop production to cherish the crop simultaneously provide ideal homogenous environments for their pathogens. In particular, large areas under monoculture production of genetically uniform plant population, fertilization, and irrigation creates an environment with fewer factors that could reduce populations or even extermination of pathogens. Moreover, the co-evolution of pathogens and their plant host may occur even faster in agricultural ecosystems (agro-ecosystems) than in natural ecosystems. Because of the implementation of agricultural techniques and pest management, the agricultural field is less prone to environmental fluctuations. Therefore, it is important to understand the evolutionary processes especially because speciation may occur more rapidly for plant pathogens than for other organisms. In the 21st century, the principles of evolutionary biology are implemented in phytopathology because of the understanding of the evolutionary processes that leading to the emergence of new pathogens. Understanding that the nature of the agro-ecosystems has played and continues to play a critical role in

**II**

**Chapter 8 117**

Management of Plant Disease **131**

**Chapter 9 133**

**Chapter 10 169**

**Chapter 11 183**

**Chapter 12 215**

Emerging Bacterial Disease (Leaf Scald) of Sugarcane in China: Pathogenesis, Diagnosis, and Management *by Muralidharan Govindaraju, Yisha Li and Muqing Zhang*

Choosing an Adequate Pesticide Delivery System for Managing Pathogens with Difficult Biologies: Case Studies on *Diplodia corticola,* 

*by Srđan G. Aćimović, Danielle K.H. Martin, Richard M. Turcotte,* 

Management of the Cacao Swollen Shoot Virus (CSSV) Menace

Emergence of Benzimidazole- and Strobilurin-Quinone Outside Inhibitor-Resistant Strains of *Colletotrichum gloeosporioides* sensu lato, the Causal Fungus of Japanese Pear Anthracnose, and Alternative

*by Nobuya Tashiro, Youichi Ide, Mayumi Noguchi, Hisayoshi Watanabe* 

Biological Control of Citrus Canker: New Approach for Disease Control

*Venturia inaequalis* and *Erwinia amylovora*

*Christopher L. Meredith and Isabel A. Munck*

in Ghana: The Past, Present and the Future

*by Sonia Villamizar and Juan Carlos Caicedo*

*by George A. Ameyaw*

*and Mizuho Nita*

Fungicides to Resistant Strains

**Section 3**

the emergence and spread of pathogens is essential to assessing the risks posed by potential future pathogens. When it is possible to predict the occurrence and spread of the pathogen, the control strategies can be developed.

New discoveries and insights into the plant-pathogen interaction and their coevolution are requiring revisions to existing knowledge about familiar plant pathogens. For instance, Common Barberry (*Berberis vulgaris*) is a major alternative host for the stem rust pathogen (*Puccinia graminis f. sp. tritici*) and was recently found in China to be an alternative host for the stripe rust pathogen (*P. striiformis f. sp. tritici*) although their associations have not been found in US Pacific Northwest. The new liberibacter species *Candidatus Liberibacter solanacearum* was first identified in 2008, simultaneously in the United States and New Zealand in tomato and pepper and then in potato, as well as several other solanaceous species. Recently, this species of liberibacter has also been documented in Northern Europe on carrot (*Daucus carota* L.) and the Mediterranean Region on celery (*Apium graveolens*). In August 2012, it was identified in France in two commercial carrot fields infested with its insect vector, the psyllid *Trioza apicalis*. Their introduction in the region is not clear and they are currently under eradication. Recently, downy mildew of Basil (*Ocimum basilicum*) has become one of the most destructive diseases of Sweet Basil, which is grown as a specialty crop in greenhouses. The problem is especially pronounced in eco-grown plants because of the limited fungicide use. Once infected, Basil plants are no longer marketable. Another, new downy mildew disease, caused by *Peronospora aquilegia*, has recently devastated and rapidly spread throughout numerous gardens and nurseries of the ornamental *Aquilegia* in the UK, but so far does not seem to have reached continental Europe.

This book is a response to the increasing interest in some plant pathogens that arise as new threats to modern plant production worldwide. The table of contents provides a descriptive feel about the topics which seize the attention and concern of phytopathologists today. The book is composed of three sections. The number of literature citations was not restricted and this constitutes a strength of the book.

Section I - *Host-pathogen coevolution* delivers an overview of new insights on existing pathogens that have begun to show a new face as a result of adapting to their host's existing production conditions. Here the readers can read about: i) the threat of rapid global spread of devastating downy mildew on Basil; ii) the difficulties of monitoring asymptomatic infections using PCR based methods especially of monitoring asymptomatic infections caused by the pathogen of Witches Broom disease of lime, and iii) leaf scald of sugarcane recently found in China and now becoming a serious threats to sugar industries.

Section II - *Novel approaches to plant disease* has the most chapters as much of the progress in plant pathology has been in the areas of how plants defend themselves against pathogens, how pathogens can be suppressed by other beneficial organisms, and the near future applicable methods exploiting discoveries in molecular genetics. Here the reader will read about: i) expanding prospects of nanotechnology in plant pathology; ii) the safe and effective alternative to control various phytopathogens by phytochemicals derived from secondary metabolism of medicinal plants, iii) two different approaches for biological control of *Xanthomonas citri* subsp. *citri* the possible bio-agent of *Pseudomonas* bacteria and inhibitors of quorum quenching; and iv) near-future management strategies in the production of major

**V**

cultivated vegetable crops from *Solanaceae* and *Cucurbitaceae* family such as genome editing, engineering rootstocks for tobamovirus resistance, and implementation of

Section III - *Management of plant diseases* also gives insight into novelties in the area of fungicide-resistance and new application techniques. Here the reader will read about: i) new threats of resistance to stroubilurines of strobilurin-quinone resistant strains of *Colletotrichum gloeosporioides,* the causal agent of Japanese pear anthracnose; ii) current research efforts and strategies aimed at minimizing of cacao swollen shoot virus (CSSV) disease continuous spread and devastation on Ghana's cocoa production, new techniques for delivering the chemicals; and iii) possibilities to control *Venturia inaequalis* and *Erwinia amylovora* by trunk injection of fungicides

This book is not only an interesting mix of all the topics discussed above but a compilation of the recent methods and knowledge about plant pathogens that are at the present time found to be of most concern. There is no doubt that the future will introduce some new plant pathogens and new concerns and problems will arise with them. Due to the simultaneous co-evolution of plants and their pathogens, all of our present-day knowledge will change in the future. In recent times, several plant pathogenic fungi have been reported as pathogenic to humans posing serious health challenges in both relatively healthy individuals as well as in those with serious underlying medical conditions. Since the 1980s at least 100 fungi not previously connected with disease in humans, have been identified as pathogenic. Some plant pathogenic fungi implicated in human diseases are *Mucor mucedo*, *Penicillium chrysogenum*, *Alternaria tenuis*, *Aspergillus flavus*, *Curvularia lunata*, *Fusarium culmorum*, *Botryodiplodia theobromae*, *Trichoderma hazianum* and *Bipolaris* sp. These fungi are melanized and melanin is considered as one of their major virulence factors. Plant-attacking mycoflora capable of causing human mycoses has stirred up public health concerns. This has imposed new challenges to scientists, among them phytopathologists, and they need to join forces to combat and find novel user-friendly antifungal compounds to maintain

Phytopathology has experienced a major increase in attention and in an atmosphere of constant evolutionary change, we must ask: *Quo vadis* Phytopathology? If we draw a parallel with historical development, we can predict that phytopathology will retain the image of necessity and will extend into new science fields. Like Alice in Wonderland said, *"If we wish to go anywhere we must run twice as fast as that"* so

I would like to express my appreciation to all the authors and co-authors that collaborated on this book. They are all recognized authorities in their field of expertise

I am especially grateful to Mrs. Lucija Tomičić Dromgool, Commissioning Editor of IntechOpen who contacted me and encouraged me to become the editor of this

I would also like to thank Mr. Gordan Tot, Author Service Manager of IntechOpen

for his assistance and kind understanding during the publication process.

cross- protection approach.

used for *Diplodia corticola*.

human health.

we need to constantly broaden our knowledge.

and this book is based on their research.

book and for the kind empathy in my loss.

cultivated vegetable crops from *Solanaceae* and *Cucurbitaceae* family such as genome editing, engineering rootstocks for tobamovirus resistance, and implementation of cross- protection approach.

Section III - *Management of plant diseases* also gives insight into novelties in the area of fungicide-resistance and new application techniques. Here the reader will read about: i) new threats of resistance to stroubilurines of strobilurin-quinone resistant strains of *Colletotrichum gloeosporioides,* the causal agent of Japanese pear anthracnose; ii) current research efforts and strategies aimed at minimizing of cacao swollen shoot virus (CSSV) disease continuous spread and devastation on Ghana's cocoa production, new techniques for delivering the chemicals; and iii) possibilities to control *Venturia inaequalis* and *Erwinia amylovora* by trunk injection of fungicides used for *Diplodia corticola*.

This book is not only an interesting mix of all the topics discussed above but a compilation of the recent methods and knowledge about plant pathogens that are at the present time found to be of most concern. There is no doubt that the future will introduce some new plant pathogens and new concerns and problems will arise with them. Due to the simultaneous co-evolution of plants and their pathogens, all of our present-day knowledge will change in the future. In recent times, several plant pathogenic fungi have been reported as pathogenic to humans posing serious health challenges in both relatively healthy individuals as well as in those with serious underlying medical conditions. Since the 1980s at least 100 fungi not previously connected with disease in humans, have been identified as pathogenic. Some plant pathogenic fungi implicated in human diseases are *Mucor mucedo*, *Penicillium chrysogenum*, *Alternaria tenuis*, *Aspergillus flavus*, *Curvularia lunata*, *Fusarium culmorum*, *Botryodiplodia theobromae*, *Trichoderma hazianum* and *Bipolaris* sp. These fungi are melanized and melanin is considered as one of their major virulence factors. Plant-attacking mycoflora capable of causing human mycoses has stirred up public health concerns. This has imposed new challenges to scientists, among them phytopathologists, and they need to join forces to combat and find novel user-friendly antifungal compounds to maintain human health.

Phytopathology has experienced a major increase in attention and in an atmosphere of constant evolutionary change, we must ask: *Quo vadis* Phytopathology? If we draw a parallel with historical development, we can predict that phytopathology will retain the image of necessity and will extend into new science fields. Like Alice in Wonderland said, *"If we wish to go anywhere we must run twice as fast as that"* so we need to constantly broaden our knowledge.

I would like to express my appreciation to all the authors and co-authors that collaborated on this book. They are all recognized authorities in their field of expertise and this book is based on their research.

I am especially grateful to Mrs. Lucija Tomičić Dromgool, Commissioning Editor of IntechOpen who contacted me and encouraged me to become the editor of this book and for the kind empathy in my loss.

I would also like to thank Mr. Gordan Tot, Author Service Manager of IntechOpen for his assistance and kind understanding during the publication process.

**IV**

the emergence and spread of pathogens is essential to assessing the risks posed by potential future pathogens. When it is possible to predict the occurrence and spread

New discoveries and insights into the plant-pathogen interaction and their coevolution are requiring revisions to existing knowledge about familiar plant pathogens. For instance, Common Barberry (*Berberis vulgaris*) is a major alternative host for the stem rust pathogen (*Puccinia graminis f. sp. tritici*) and was recently found in China to be an alternative host for the stripe rust pathogen (*P. striiformis f. sp. tritici*) although their associations have not been found in US Pacific Northwest. The new liberibacter species *Candidatus Liberibacter solanacearum* was first identified in 2008, simultaneously in the United States and New Zealand in tomato and pepper and then in potato, as well as several other solanaceous species. Recently, this species of liberibacter has also been documented in Northern Europe on carrot (*Daucus carota* L.) and the Mediterranean Region on celery (*Apium graveolens*). In August 2012, it was identified in France in two commercial carrot fields infested with its insect vector, the psyllid *Trioza apicalis*. Their introduction in the region is not clear and they are currently under eradication. Recently, downy mildew of Basil (*Ocimum basilicum*) has become one of the most destructive diseases of Sweet Basil, which is grown as a specialty crop in greenhouses. The problem is especially pronounced in eco-grown plants because of the limited fungicide use. Once infected, Basil plants are no longer marketable. Another, new downy mildew disease, caused by *Peronospora aquilegia*, has recently devastated and rapidly spread throughout numerous gardens and nurseries of the ornamental *Aquilegia* in the UK, but so far

of the pathogen, the control strategies can be developed.

does not seem to have reached continental Europe.

a serious threats to sugar industries.

This book is a response to the increasing interest in some plant pathogens that arise as new threats to modern plant production worldwide. The table of contents provides a descriptive feel about the topics which seize the attention and concern of phytopathologists today. The book is composed of three sections. The number of literature citations was not restricted and this constitutes a strength of the book.

Section I - *Host-pathogen coevolution* delivers an overview of new insights on existing pathogens that have begun to show a new face as a result of adapting to their host's existing production conditions. Here the readers can read about: i) the threat of rapid global spread of devastating downy mildew on Basil; ii) the difficulties of monitoring asymptomatic infections using PCR based methods especially of monitoring asymptomatic infections caused by the pathogen of Witches Broom disease of lime, and iii) leaf scald of sugarcane recently found in China and now becoming

Section II - *Novel approaches to plant disease* has the most chapters as much of the progress in plant pathology has been in the areas of how plants defend themselves against pathogens, how pathogens can be suppressed by other beneficial organisms, and the near future applicable methods exploiting discoveries in molecular genetics. Here the reader will read about: i) expanding prospects of nanotechnology in plant pathology; ii) the safe and effective alternative to control various phytopathogens by phytochemicals derived from secondary metabolism of medicinal plants, iii) two different approaches for biological control of *Xanthomonas citri* subsp. *citri* the possible bio-agent of *Pseudomonas* bacteria and inhibitors of quorum quenching; and iv) near-future management strategies in the production of major

Finally, completion of this undertaking could not have been possible without IntechOpen staff and their contribution is gratefully acknowledged.

> **Snježana Topolovec-Pintaric** Professor, Faculty of Agriculture, University of Zagreb, Croatia

> > **1**

Section 1

Novel Approaches to Plant

Disease

## Section 1
