The association of Prunus ringspot, prune dwarf, and dark green sunken mottle viruses in the rosetting and decline disease of peach

Abstract

The symptoms of a rosetting and decline disease of peach are described. Prunus necrotic ringspot virus (PRSV), prune dwarf virus (PDV), and a virus which causes a dark green sunken mottle (DGSM) on peach leaves have been isolated from diseased trees. Combinations of these viruses interacted synergistically in peach seedlings, but with considerable variation in the degree of synergism. The most severe expression of rosetting resulted from the interaction of all three viruses. Interaction between PRSV and PDV usually caused recurrent rosetting. PRSV and PDV were transmitted through the seed of rosetted peaches, but the latter in only a low percentage of seeds (max. 6%) and then only in combination with PRSV, which was transmitted to a maximum of 35.7 %. There was no evidence for seed transmission of DGSM. A study of natural spread of rosetting in a commercial planting of Golden Queen peaches showed that rosetted trees increased from 0.8 to 56.1 %, a total of 265 in 472 trees, in 7 years. Seedlings grown in soil obtained from the root zone of infected trees did not become infected.