Over the past decade, virology has achieved remarkable successes. In particular, theoretical virology has advanced rapidly during this period. It is no exaggeration to say that the theoretical problems of virology now occupy one of the central positions in the life sciences. However, despite these achievements, the nature of viruses has still not been fully revealed. Just as when the Russian scientist D. I. Ivanovsky first discovered viruses in the world sixty years ago, we still lack decisive evidence to support any particular view regarding the origin of these infectious agents. This indicates the need for a major expansion of experimental research in this field. At the same time, it must be emphasized that every new advance in understanding the nature of viruses contributes to the prevention and control of viral infections. Our country has achieved significant successes in the study of plant virus diseases. However, this knowledge has not yet been fully applied in agricultural production, nor does it meet the scale of work required by socialist agriculture. Given the vast sown areas of our country, the diversity of crops, and the complexity of their cultivation conditions, it is essential to fundamentally improve both experimental research on plant virus diseases and the development of measures for their prevention and control. To achieve this, it is first necessary to investigate the types of virus diseases commonly occurring in different crops and to establish a systematic classification of these diseases. It is also well known that even for virus diseases that have already been studied, sufficiently effective control measures have not yet been developed. Therefore, this area still offers broad opportunities for further research. In order to address the major tasks facing our virologists, a series of serious organizational measures must be adopted. Among the most important are the establishment of scientific centers for virological research and the training of virology specialists, who are currently in extremely short supply. In February 1958, the All-Union Conference on Plant Virus Diseases was convened. The work of this conference will undoubtedly have a positive impact on the further development of virological research and will help achieve new accomplishments worthy of advanced socialist science. This volume contains papers related to the principal issues discussed at the conference.