An important new apricot disease in Spain is associated with Hop stunt viroid infection

The province of Murcia (Murcia Region) is the one of the most important apricot growing regions in Europe. In recent years a fruit disorder named by growers as "degeneracion" has been detected in apricot commercial orchards of this region, mainly in the variety Velazquez Fino. Affected fruits are characterized by changes in their external appearance involving rugosity and a loss of organoleptic characteristics, which leads to an unmarketable product. In order to identify the causal agent of this disorder, the presence of the most important viruses affecting stone fruit trees and Hop stunt viroid (HSVd) was tested. While negative results were obtained for all viruses analysed, the viroid was detected in all the symptomatic trees. Within a single tree, the viroid was restricted to branches bearing fruits with the characteristic symptoms but was usually absent from the rest of the tree. Sequence analysis of several isolates of HSVd obtained from these affected trees revealed the presence of two variants previously detected in other apricot cultivars. Taken together, these results suggest that degeneration is associated with HSVd.