The occurrence and distribution of isolates of raspberry bushy dwarf virus in England

The distribution of distinct isolates of raspberry bushy dwarf virus (RBDV) in Rubus in England was studied. Isolates similar in Rubus host range to the Scottish type isolate (D200) were largely confined to the old red raspberry (Rubus idaeus) cv. Norfolk Giant, but were also encountered in a single plant of an unidentified raspberry cultivar and in a clump of wild R. idaeus. Outside East Mailing Research Station (EMRS) RBDV isolates with wider Rubus host ranges than that of the type isolate were found only and exclusively in hybrid berries (Loganberry, clones LY59 and L654, and Tayberry) in which infection ranged from < 1% to 100%. The significance of these findings is discussed.