plant disease must take all four components into account. Obviously, one needs to be familiar with the characteristics of the host and the pathogen in isolation. The successful establishment of a pathogen in its host gives rise to the host–pathogen complex. Unraveling the dynamic sequence of events during infection, the molecular “cross‐talk” taking place between the partners, is one of the most challenging problems in experimental biology. In addition, the effects of the environment on each of other components must be understood. This includes not only physical and chemical factors but also macro‐ and microbiological agents. The two‐way arrow between the host and the environment in Figure 1b should not be overlooked, as populations of crop plants often have important effects on their surrounding microclimate. For example, the relative humidity within a crop canopy is higher than that outside and this will favor the development of some microorganisms. Plants attacked by pests and pathogens often produce volatile compounds that can act as signals sensed by neighboring plants. Effects of pathogens on the environment are more subtle but may be significant; some fungi, for instance, produce the volatile hormone ethylene, which can in turn affect the development of adjacent host plants.
Figure 1 The disease triangle (a) incorporating the host–pathogen complex (b).
This book is intended to provide an outline of the main elements of modern plant pathology. The approach is designed to achieve a balance between laboratory and field aspects of the subject, and to place the phenomenon of plant disease in a wider biological context. Research in plant pathology can be broadly divided into tactical and strategic aspects. The former is concerned with providing solutions to disease problems by identifying causal agents and evaluating the most cost‐effective options for their control. The latter is longer term and aims to understand fundamental aspects of plant disease such as pathogen ecology, population biology, host–pathogen interactions, and plant immunity. This knowledge can then be applied to devise improved methods of disease control.
The book is divided into three parts. The first focuses on the problem of plant disease, the causal agents and their significance, disease diagnosis, and the development of epidemics in plant populations. This account highlights the influence of environmental factors on the multiplication and spread of pathogens, and the use of climate data in disease prediction. The second part deals with host–pathogen interactions: how pathogens gain entry to the host, how their growth and development in the plant lead to disease symptoms, and how the plant responds. The outcome of any host–pathogen confrontation depends on a dynamic interplay between factors determining microbial pathogenicity and the active mechanisms of plant immunity. This interaction ultimately determines host–pathogen specificity, whereby any pathogen is able to cause disease in only a restricted range of host plants. Plant and molecular biologists are studying host–pathogen systems as experimental models to probe the mechanisms of gene expression and regulation, and to reveal details of the evolutionary “arms race” taking place between plants and pathogens. Part III deals with the practical business of disease control, often described as crop protection. This covers the management of disease by means of chemicals, breeding for resistance, and alternative biological approaches. Finally, the combined use of cultural practices and all these other measures to provide sustainable, integrated systems for disease control is described.
A comprehensive treatment of individual diseases and the methods used in their control is beyond the scope of a text of this length. For the sake of brevity, specific pathogens or the diseases they cause are often mentioned without further explanation. This approach may be likened to that adopted in many ecology texts, in which the reader is expected to be familiar with most of the higher plants or animals discussed therein. There is, however, an appendix listing all the pathogens and diseases mentioned in the book, together with brief details which will enable the reader to obtain further information about particular diseases. More detail concerning specific aspects of pathology may be obtained by consulting the recommended further reading.
Further Reading
Books
1 Agrios, G. (2005). Plant Pathology, 5e. Amsterdam: Elsevier Academic Press.
2 Schumann, G.L. and D'Arcy, C.J. (2009). Essential Plant Pathology, 2e. St Paul, Minnesota: American Phytopathological Society Press.
3 Strange, R.N. (2003). Introduction to Plant Pathology. Chichester: Wiley.
Reviews and Papers
1 Foley, J.A., Ramankutty, N., Brauman, K.A. et al. (2011). Solutions for a cultivated planet. Nature 478: 337–342.
2 Godfray, H.C.J., Beddington, J.R., Crute, I.R. et al. (2010). Food security: the challenge of feeding 9 billion people. Science 327: 812–818.
3 Savary, S., Bragaglio, S., Willocquet, L. et al. (2017). Crop health and its global impacts on the components of food security. Food Security 9: 311–327. https://doi.org/10.1007/s12571‐017‐659‐1.
Scientific Journals
Many scientific journals contain reviews and research papers relevant to plant pathology. One especially useful source is the Annual Review of Phytopathology. Others include:
Advances in Botanical Research
Annals of Applied Biology
Crop Protection
European Journal of Plant Pathology
Fungal Genetics and Biology
Journal of Phytopathology
Molecular Plant–Microbe Interactions
Molecular Plant Pathology
Mycological Research
New Phytologist
Pest Management Science
Plant Disease
The Plant Cell
The Plant Journal
Physiological and Molecular Plant Pathology
Phytopathology
Plant Pathology
PLOS Pathogens
American Phytopathological Society: www.apsnet.org
British Society of Plant Pathology: www.bspp.org.uk
European Foundation for Plant Pathology: www.efpp.net
Review of Plant Pathology, an abstracts database of plant pathology research: www.cabi.org/publishing‐products/online‐information‐resources/review‐of‐plant‐pathology
