2012 Annual Report 1a.Objectives (from AD-416): Conduct genetic diversity studies among economically important grapevine viruses documented in the Pacific Northwest region. 1b.Approach (from AD-416): It is imperative that molecular diversity studies be completed for the major viruses in the PNW region to improve our understanding of the spectrum of their variability for the development of improved diagnostic tools in order to be able to detect all the strains of a given virus and prevent their spread in PNW vineyards. Towards this goal, we will initially focus molecular diversity studies on GLRaV-2, GVA, GVB, GRSPaV, GFLV and ToRSV. We will extend these studies to other GLRaVs during the course of this project, if there is an indication of molecular variability among these viruses. 3.Progress Report: Grapevines, due to their perennial nature, can harbor genetically diverse viruses and their strains in a single plant. Genetically diverse populations of grapevine viruses, frequently generated owing to the error-prone nature of the viral replicase, can accumulate with time due to clonal propagation of grapevine cultivars and disseminate via cuttings into new areas, causing a sustained threat to the wine grape industry in the affected areas. In this context, analyzing the spectrum of viruses and their variants from different wine grape cultivars will improve our understanding of the sanitary status of vineyards in the Pacific Northwest region and provide necessary information for the development of better diagnostic tools and sound management practices resulting in reduced spread and economic impact of several debilitating viruses and their variants. In this context, we have completed molecular characterization of Grapevine Virus E, a new virus documented in Washington and Oregon vineyards. This information is being used in clean plant programs to provide virus-tested planting materials for wine grape growers in the Pacific Northwest region. The science-based information has been disseminated to growers and other stakeholders through extension and outreach programs for increased knowledge of viruses and their impacts on sustainability of the wine grape industry in the region. This research was conducted in support of objective 3B of the parent project.