Cherry Leaf Roll Virus in Juglans regia in the United Kingdom

Abstract

Cherry leaf roll virus (CLRV) was detected in foliage, pollen or seeds of 43 of 113 mature/overmature Juglans regia L.; two had foliar yellow-brown ring patterns whereas seven other infected trees had leaf necroses. Male catkins of a few infected trees were malformed and blackened. Infection was rare (3/43) in the widely scattered J. regia of northern England and Scotland, but commoner (40/70) in southern England. When J. regia seed was grown in methylbromide treated soil, six per cent (18/300) of the seedlings were symptomlessly infected. Four out of ten groups of imported seedlings were infected to a similar extent, CLRV being present in a total of 40 out of 1146 trees aged five years or less. When 3 years old, CLRV infected J. regia were shorter and thinner than healthy seedlings. CLRV from walnut was serologically distinguishable from Betula, Prunus, Cornus and Sambucus isolates. One English walnut isolate (Ox) was distinguishable from two Italian walnut isolates. An isolate (Sr) of CLRV obtained in Finland from Sambucus racemosa L. was antigenically distinct from S. ebulus and S. nigra isolates.