**5. Cryotherapy and virus elimination**

An important pre-requisite for the conservation of germplasm either *in vitro* or under cryopreservation is the availability of 'virus-free' starting material. The presence of viruses hinders international and national exchange and conservation of germplasm and also becomes a hurdle for utilization of germplasm in its crop improvement. The viruses cause the most serious diseases in *Fragaria.* Viruses causing serious diseases are arabis mosaic virus (ArMV), raspberry bushy dwarf virus (RBDV), strawberry mild yellow edge virus (SMYEV) and raspberry ringspot virus (RpRSV). These viruses are transmitted during traditional vegetative propagation through runners or by modern methods of *in vitro* multiplication. Thus, periodic screening for *in vitro* conserved *Fragaria* germplasm is important for viruses' status in an *in vitro* genebank [60].

It was established for the first time that cryopreservation was not only useful for germplasm conservation, but also for virus eradication in *in vitro* shoots of plum infected with plum pox virus (PPV) [61]. Cryotherapy is a novel method for virus eradication in economically important plant species [62]. In Cryotherapy, more hydrated, infected cells die because of freezing, and only small compact cells which are close to the meristem and generally virus-free survive cryopreservation [63]. Cryotherapy has been attempted for virus eradication in many important crops such as banana, grapevine, *Prunus*, raspberry, citrus and potato. In *F. vesca* post-cryotherapy 96.67% of cultures were found free from *Raspberry ringspot virus* (RpRSV) [64].
