Nematode-borne viruses of grapevine, their epidemiology and control

The discovery of a nematode vector for the fanleaf disease of grapevine (Hewitt et al., 1958) together with the demonstration that the viral agent was mechanically transmissible to herbaceous hosts (Cadman et aI., 1960) greatly stimulated investigations on viruses of cultivated Vi tis. Consequently, in little less than two decades many different viruses have been manually transmitted from diseased vines in several grape-growing countries. By 1976 there were 24 viruses recorded from grapevine (Martelli, 1978) half of which are either recognized or putative members of the nepovirus group (Table I). At present, nepoviruses are the only nematode-borne pathogens known to infect grapevine in which they may cause destructive diseases. Although occurring in the major viticultural areas of the world, not all the viruses are equally widespread. Thus, with the exception of grapevine fanleaf virus (GFV) which is ubiquitous (Hewitt, 1968) and uniquely specialized for having no natural host other than grapevine, other viruses like arabis mosaic (AMV), tomato black ring (TBRV), raspberry ringspot (RRV), strawberry latent ringspot (SLRV), grapevine chrome mosaic (GCMV), and artichoke Italian latent (AILV) are restricted to European countries (Table I). These will be referred to as European nepoviruses as opposed to American nepoviruses, i.e. tomato ringspot (TomRSV) tobacco rings pot (TRSV) and peach rosette mosaic (PRSV) which seem confined largely to North America. Besides GFV, grapevine Bulgarian latent (GBLV) is the only grapevine nepovirus recorded, so far, in both Europe and North America. Various aspects of the biology and ecology of nematode-transmitted viruses have been reviewed in recent times in articles which also contain much information on those infecting grapevine (Murant, 1970; Taylor, 1971, 1972; Vuittenez et al., 1972; Weischer, 1973, 1975; Taylor and Robertson, 1975; Harrison, 1977; Lamberti, 1978).