(Wines&Vines) - The Napa Valley Grapegrowers held the second in a series of Sustainable Vineyard Practices seminars April 24 in Yountville. The session of most interest focused on nursery vines for planting and replanting, and moderator Remi Cohen from Cliff Lede Vineyards started the discussion among a panel from leading nurseries by raising the problems growers face due to high demand for vines to plant—and a recent explosion of grapevine viruses.

Leafroll virus, spread by the vine mealy bug, was already a growing problem. A few years ago red blotch (formerly red blotch-associated virus) started sweeping through vineyards in Napa Valley. Because red blotch isn’t fully understood, universities, nurseries and growers alike are struggling to deal with its impact.