Viruses and virus-like diseases affecting Betula spp

Abstract

SynopsisSeven virus-like agents have been recognized naturally infecting birches in Europe or North America. Of these, only two have been studied in detail. Apple mosaic virus (AMV) infects Betula papyrifera and B. alleghaniensis in North America, and is associated with golden-white ring/line patterns in leaves. There is no evidence that AMV spreads between birches and no natural means of dissemination is known. In Europe, B. verrucosa and B. pubescens are naturally infected with cherry leaf roll virus (CLRV) which causes foliar mottle, pale yellow spots and bright green vein banding. In the United Kingdom, the prevalence of CLRV in unmanaged birch populations is less than in street trees. The virus is spread via birch seed and pollen which it infects and also contaminates. Sparse data suggest that the following viruses infect birch but their effects are unknown: yellow birch latent, tobacco rattle, tobacco necrosis, prunus necrotic ringspot and prune dwarf. There is a similar paucity of information concerning the cause of wood abnormalities that enhance the veneer value of affected timber: agents transmitted in soil or by grafting have been associated.