RESULTS OF THE STUDY OF NEW SWEET CHERRY CULTIVARS AND ELITES IN KYUSTENDIL REGION, BULGARIA

Thirteen sweet cherry (Prunus avium L.) cultivars were studied from 1997 to 2005 in an experimental orchard at the Institute of Agriculture in Kyustendil, Bulgaria. The trees were planted in 1996. All were grafted on P. mahaleb. Four biological properties were assessed: bloom date, harvest date, fruit mass and average yield per tree. Elite ‘№ 5645’ is interesting because it is very early ripening, productive, has good fruit mass and is only moderately susceptible to cherry leaf spot (Blumeriella jaapii). Good results were obtained for the mid-season ripening ‘Krupnoplodnaya’. ‘Ranochnaya’ had very low susceptibility to cherry leaf spot, whereas ‘Sovetskaya’, ‘Merchant’ and the standard ‘Bing’ were highly susceptible. All serologically assayed trees of ‘Seneca’, ‘Burlat’, Elite ‘№ 5645’, ‘Frue rote Meckencheimer’, ‘Nadezda’, ‘Ranochnaya’, three trees of ‘Krupnoplodnaya’ and one tree of ‘11W- 15-37’ were free of all tested viruses. The viruses detected in other trees included: Prunus necrotic ringspot (PNRSV), Prune dwarf (PDV) and Apple chlorotic leaf spot (ACLSV); no detection of Cherry leaf roll virus (CLRV), Raspberry ringspot virus (RpRSV), Plum pox virus (PPV) or Apple mosaic virus (ApMV) was found.