ABSTRACT
Kassanis and co-workers used the term "cryptic" to describe the virus in sugar beets which induced no symptoms, was seed transmitted, but was not transmitted by grafting or by mechanical inoculations. The ICTV has classified viruses exhibiting the following properties as forming the Cryptovirus group: isometric particles containing segmented dsRNA, transmitted only by seed and pollen, occurring in very low concentrations in host cells, and most of the viruses not associated with obvious symptoms. Properties of cryptoviruses have been reviewed by Boc-cardo and co-workers, Francki and co-workers, and Kuhne and co-workers. Effects on legumes of mixed infections involviug cryptoviruses and viruses in other groups are unknown. That they may be negligible is suggested by results of mixed infections of ryegrass cryptic virus and ryegrass mosaic potyvirus. The original alfalfa cryptic virus discussed by Boccardo and co-workers has been shown to have been a mixture of a cryptovirus with ca. 30-nm particles and a cryptovirus with a ca. 38-nm-diameter particle.
