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

Abstract

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. idueus. Outside East Malling 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.

Occurrence and distribution of Raspberry bushy dwarf virus in commercial Rubus plantations in England and Wales

“…Recently, a similar wide spread of RBDV infection in raspberry (including wild plants) has been found in Scotland (Chard et al ., 2000). In 1997, 10 of the 45 plots (22%) of hybrid berries (Loganberry and Tayberry) tested in this study were found to be infected, very similar to the rate found in Loganberry in the 1982–83 survey with seven plots infected out of 30 tested; 23% (Barbara et al ., 1985). Tayberry was only recently introduced in 1982–83 and not widely grown, so no plots were tested.…”

“…Assuming that infection has arisen from foci on or near commercial farms, there are at least three possible sources of RBDV. Firstly, although only limited numbers of wild (or feral) raspberries have been tested, some of these have been found to be infected in both England and Wales with either non‐RB strains (Barbara et al ., 1985) or strains of unknown pathotype (this work), and in Scotland with an unknown pathotype (Chard et al ., 2000). Secondly, some old RBDV‐infected material of cultivars such as Norfolk Giant will still exist in gardens, allotments or in poorly managed or abandoned commercial plantings.…”

“…A third potential source would be hybrid berries. In 1983, RB isolates were widespread in England in hybrid berries and circumstantial evidence suggested that RB isolates had been present in commercial hybrid berries for more than 20 years (Barbara et al ., 1985). At that time they had clearly not spread from these hosts into commercial raspberry but may now have done so, possibly due in some way to the change in cultivars grown.…”

“…c ±, no plots of this age sampled. (Barbara et al, 1985). Tayberry was only recently introduced in 1982±83 and not widely grown, so no plots were tested.…”

“…At that time, resistance‐breaking (RB) isolates of RBDV in red raspberry were only found at the East Malling site of Horticulture Research International, but were more generally distributed in the UK in commercial Loganberry (a raspberry/blackberry hybrid) plantings (Barbara et al ., 1985). Circumstantial evidence suggested that RB‐RBDV had been present in some Loganberry plantations for at least 25 years prior to that survey (Legg, 1960; Barbara et al ., 1985).…”