Peach red marbling and peach sooty ringspot, two new virus-likedegenerative diseases of Prunus

摘要

More than 600 Prunus samples were examined by using a nonradioactive digoxigenin-labelled RNA probe specific for hop stunt viroid (HSVd). Prunus salicina and Prunus armeniaca appeared to be better hosts than Prunus persica. The weak viroid concentration in flowers and young leaves of peach trees growing in the field did not permit its detection in such samples. The diagnosis was more reliable (about 85%) with bark and leaves aged 4 months and more, from regrowths of GF 305 peach seedlings inoculated and kept in the greenhouse. Detection of HSVd in leaves and bark of apricot and Japanese plum plants aged 3 months or more also proved reliable (about 80% and 90%, respectively). HSVd could be transmitted in apricot, peach and plum nucleic acid preparations to GF 305 peach seedlings by repeated stem slashing, and to cherries (Prunus avium and Prunus serrulata) by approach grafting with an infected P. salicina source. The viroid was eliminated from 18% of the clones obtained after thermotherapy.