ABSTRACT
Early detection of pathogenic infection is essential to eliminate all infected seeds and planting materials which form primary sources of infection and to rogue out infected plants present in the field whenever possible. The detection and characterization of plant pathogens usually depend on isolation of the pathogen and recording of the symptoms it induces on susceptible host plants. This procedure is a time-consuming process and often cannot be used to distinguish reliably between closely related species and strains of the pathogen, necessitating the use of faster and more discriminating detection methods. The methods of detecting plant pathogens may be divided into two groups: a) specific methods which may be used to detect a particular species or group ofpathogens after preliminary diagnosis suggesting the presence of the particular pathogen, b) nonspecific methods which may be employed in detection of unknown pathogens or when the presence of a number of pathogens is to be detected, as in plant quarantines (Chu et aI., 1989). However, the use of the term specific or nonspecific to indicate the extent of the reliability of a method to be employed for the detection of pathogens will be more appropriate. Thus serological and nucleic acid hybridization methods can be considered as more specific and reliable than most of chemical methods, which are often found to be nonspecific and less reliable, though these methods are simpler.
