Cryotheraphy - More recently, prolonged exposure to a low temperature (5˚C), followed by shoottip culture has proved quite successful in virus elimination; this is often called Cryotherapy. For example, shoot tip cultures from Chrysanthemum plants treated with 5˚C for 4 months yielded 67% plants free from chrysanthemum stunt virus (CSV).

The frequency of virus-free plants increased to 73% after a 7;5 month exposure to 5°C. Cold treatment is preferable to heat-treatment as it is less injurious to the plants and often more effective in virus elimination.