VARIATION IN HORTICULTURAL TRAITS OF BING SWEET CHERRY ASSOCIATED WITH ILARVIRUS INFECTION

Thirty-five 'Bing' sweet cherry (Prunus avium L.) clones were collecte d, primarily from old commercial orchards in central Washington; propa gated on P. mahaleb L. rootstock; and their horticultural performance was evaluated. Nine of the 35 clones were not infected with the common pollen-borne ilarviruses prunus necrotic ringspot virus and prune dwa rf virus-four of the clones after decades of exposure in commercial or chards. As a group, the nine virus-free clones produced larger trees w ith earlier fruit maturity and less rain cracking, but softer fruit, t han did the 26 infected clones. These data challenge the general assum ption that the presence of one or both of these ilarviruses is always detrimental, This assumption has driven development of many valuable v irus certification programs and the adoption of virus-free trees as th e standard for commercial fruit growing in most states.