An update on apple chlorotic leaf spot virus status of sweet cherry in Bulgaria

Abstract

The sweet cherry (Prunus avium L.) is one of the most important stone fruit species in Bulgaria. The cherry is susceptible to many viruses. To gain a better insight into the phyto-virologic status of sweet cherry, a survey for the presence of apple chlorotic leaf spot virus (ACLSV), cherry leafroll virus (CLRVR) and raspberry ringspot virus (RpRSV), in addition to ilarviruses, was carried out in 32 commercial and 6 collection orchards in ten regions of Bulgaria between 2017 and 2022. A total of 1503 sweet cherry samples were collected from symptomatic and symptomless trees. These samples were tested by cocktail ELISA for ACLSV and DAS-ELISA for CLRVR, RpRSV ?nd additionally for prune dwarf virus (PDV) and prunus necrotic ringspot virus (PNRSV) to detect mixed infections. Of the three viruses studied, only ACLSV was detected in commercial and collection sweet cherry orchards in all regions with intensive cherry cultivation in Bulgaria, in addition to ilarviruses. The extent of ACLSV virus infection was 8.8%. Single ACLSV infection was the most common, affecting 79.6% of infected sweet cherry trees, followed by ACLSV and PDV (14.4%) and least frequently by ACLSV and PNRSV (6.0%). The presence of ACLSV in orchards of different ages, including ?young? orchards, indicates that virus-free propagation material must be used when establishing new orchards to prevent the spread of pathogens with the planting material.