ABSTRACT
In the past, diagnosis of different diseases affecting crop plants was considered a form of art, and disease was diagnosed by an intuitive judgment as to its nature after examination of the visible symptoms of the disease concerned. Later, using determinations based on biochemical and physiological studies of the mechanisms of infection or the metabolic characteristics of pathogens, the diseases were diagnosed (McIntyre and Sands, 1977). It is now well recognized that the techniques for pathogen detection and diagnosis of diseases caused by them are critical factors to be considered for developing strategies for effective crop management and regulatory programs. The techniques are also required for determining the cause, epidemiological characteristics, and distribution of diseases in a geographical location.
