Studies on the incidence of ilarviruses and apple chlorotic leaf spot virus (ACLSV) in apricot trees in the Murcia Region (Spain) using serological and molecular hybridization methods

Apricot production in the Murcia Region (Spain) represents 65% of the total Spanish apricot crop. DAS-ELISA was used to determine the incidence of prunus necrotic ringspot (PNRSV), prune dwarf virus (PDV), apple mosaic virus (ApMV) and apple chlorotic leaf spot virus (ACLSV) in apricot orchards in five different areas of the Murcia Region. A total of 450 trees corresponding to four different varieties were tested. About 30% of the apricot trees were affected by at least one virus. The level of infection was 22.6% for ACLSV, 15.7% for ApMV, 10% for PNRSV and 0.4% for PDV. Double infections were observed in 23.6% of the infected trees, the most common combination being ACLSV+PNRSV. Three virus infections were detected in 2.9% of the cases. The highest level of incidence was observed in the variety 'Real Fino' (79%) while 46% of 'Bulida', the most widely grown variety in the region, was affected. In this variety a significant influence of the rootstock (Pollizo plum) was observed. The data obtained by DAS-ELISA for PNRSV were compared with a non-isotopic molecular hybridization routine analysis. The results obtained from this comparison showed that with the non-isotopic molecular hybridization technique 10% more samples were detected as positive. The possibility of using this technique as routine diagnostic method is discussed.