The knowledge of ecology and epidemiology of rhizomania is particularly useful to understand
the means and practices able to limit or avoid its further diffusion. Some promising methods of
biological control using coexisting and non-pathogenic organisms could potentially help improve
the action of the not completely effective genetic resistances. This integrated protection
would be valuable especially in the even more frequent development of resistance-breaking
strains in the BNYVV where the known types of resistance alone or in combination seem to
have lost part of their original ability to protect the crop. Therefore further efforts will
be needed to discover new traits likely still present in the wild species of the genus Beta.
The availability of large collections of germplasm stored in the International Beta gene-banks
should ensure the enhanced efficiency of genetic resistance by means of conventional and
marker-assisted selection methods. Some almost immune transgenic varieties seem already to be
waiting for release where and when it will be possible. The introduction chapter describes
briefly the sugar beet crop the more common diseases and the damage caused by rhizomania. The
following chapters discuss biological properties of the causal virus BNYVV and its vector
Polymyxa betae and their interactions with the environment and the host-plant. In particular
the great advances in research of the molecular biology of BNYVV should be noteworthy which
have been established by a wide range of the most modern methods. Recent work focused on the
genetic diversity and evolution of BNYVV is moving forward our understanding of the dramatic
worldwide epidemics of rhizomania. Newly developed molecular techniques also lead to practical
applications such as quantification of inoculum in ecological and epidemiological research.
