Biology and Spread of Grapevine Red Blotch-Associated Virus

Grapevine red blotch-associated virus (GRBaV) is the causal agent of red blotch, a recently recognized viral disease of grapevines. We showed that GRBaV can infect rootstocks following agroinoculation, including 3309C that is asymptomatic while infected. This makes clear the potential for rootstocks to be involved in virus dissemination. Efforts to develop a serological detection assay for GRBaV have been challenging, suggesting a need to investigate the expression mechanism of the coat protein gene to facilitate developing approaches to produce antibodies that will recognize virions in infected grapevine tissue. The spatial distribution of GRBaV was mapped in selected vineyards in California and New York, and preliminary work designed to identify insect vectors has provided candidate leads among a few hemipteran insects. Survey efforts of alternative hosts revealed that free-living grapevines in riparian areas in close spatial proximity to diseased vineyards in California can be infected by GRBaV. Research progress was extended to stakeholders through presentations at grower’s conventions.