Aggressiveness of Phytopathogenic Viruses: Trace Investigation and Evaluation

The paper deals with the particularities in the manifestation of aggressiveness by phytopathogenic viruses and the methods of its tracing out and evaluation. Aggressiveness is a property of phytopathogens. We present some examples of viral pathogens which cause economically important diseases in the agroecosystems of Bulgaria. We have considered the manifestation of virus aggressiveness in association with other properties which characterize plant pathogens.