Originally described as necrotic, intermediate and yellow on the basis of symptoms obtained by inoculation into herbaceous plants, these variations can now be distinguished serologically. Severe symptoms are observed on apricot, plum, and peach trees. Almond trees may be infected occasionally but show few symptoms. Sweet and sour cherries have only recently been confirmed to be natural hosts also. The virus also infects some wild Prunus species, especially P. spinosa which is an important natural source of infection in many countries.
Host ranges for different plum pox strains can be variable.
Natural plum pox virus infection on peach could not be found in Bulgaria or, until recently, in Yugoslavia. In the central and eastern European countries, PPV spread relatively early and levels of infection are generally high. In the Mediterranean countries, PPV is a more recent event and further spread is possible. In the northern and western countries, levels of PPV are very uneven and outbreaks are sporadic and usually localized, although it is fairly widespread in some areas. The main source of inoculum is infected trees.