Studies on the incidence of hop stunt viroid in apricot trees (Prunus armeniaca) by using an easy and short extraction method to analyze a large number of samples

Hop stunt viroid (HSVd) infects several fruit tree species of agronomic importance, including apricots as demonstrated recently (Astruc et nl., 1996). We have optimized a nucleic acid extraction method that avoids the use of phenolics for the analysis of large number of samples, and have used it in conjunction with a non-radioactive RNA probe to diagnose HSVd. Making use of this method, we conducted an extensive survey to detect the presence of HSVd in field-grown apricot trees in the productive areas of Murcia (Spain). This study has demonstrated that 81% of apricots were infected with the viroid. HSVd was equally distributed in all the five apricot cultivars studied as well as in the four different areas of Murcia surveyed. It has been shown too that the incidence of HSVd in apricot trees is not influenced by the presence of other economically important plant viruses of Prunus.