EXPERIMENTAL EVIDENCE THAT APPLE DIMPLE FRUIT VIROID DOES NOT SPREAD NATURALLY

A disease, named apple dimple fruit (ADF), was reported in Southern Italy first in trees of cultivar ‘Starking Delicious’ and later in ‘Royal Gala’ and ‘Annurca’. The symptoms are roundish and depressed green spots, 3-4 mm in diameter, scattered on the fruit skin.
In some cases, the spots coalesce and large discoloured skin areas appear predominantly around the calyx end.
The disease is caused by Apple dimple fruit viroid (ADFVd) that has been experimentally transmitted to other commercial apple cultivars, in which it induces typical symptoms or no symptoms at all, and to the ‘Fieud 37’ pear indicator in which no symptoms develop.
Here we report that dot- and northern-blot hybridizations of extracts from different apple and pear cultivars collected in several areas of Campania (Italy) revealed the presence of ADFVd in ‘Starking Delicious’ trees with typical fruit symptoms and in an ‘Annurca’ tree without symptoms.
The distribution and spread of the viroid, monitored over a three-year period, showed a scattered pattern of infected field trees and lack of transmission between adjacent or remote trees.
ADFVd was not detected in seedlings obtained from symptomatic fruits of an ADFVd-infected tree.
Molecular hybridizations with specific probes failed to reveal the presence of Apple scar skin viroid (ASSVd), Pear blister canker viroid (PBCVd), Hop stunt viroid (HSVd) and Peach latent mosaic viroid (PLMVd) in the apple trees tested.

XIX International Symposium on Virus and Virus-like Diseases of Temperate Fruit Crops – Fruit Tree Diseases

M. Malfitano, D. Alioto, A. Ragozzino, F. Di Serio, R. Flores

viroids, ADFVd, apple, pear

https://doi.org/10.17660/ActaHortic.2004.657.56