ABSTRACT
Plants not only sustain the man and animals, they are also the source of food for multitudes of organisms living in the ecosystem. A conflict of interest, therefore, between the contenders of suppliers from plants is inevitable. The objectives of plant pathology are to identify the causes of disease, the mechanism of disease development, the factors affecting disease development and finally economic and efficient management of diseases. Lack of an adequate definition of "disease" is not at all an impediment to the progress of plant pathology. In the history of mankind plant diseases have been connected with a number of important events. Plant diseases have been considered as stubborn barriers to the rapid progress of food production. Various schemes of classifying plant diseases have been proposed. A disease may be localized or it may be systemic. The eating habits of people are very difficult to change and plant diseases appear to be responsible for many deeply implanted eating habits.
