Grapevine red blotch virus, as seen here in a Zinfandel orchard in Northern California, reduces fruit quality by disrupting photosynthesis, according to a recent study by University of California, Davis, scientists. The fruit acquire less sugar and don’t produce enough of the desired anthocyanins, said viticulture extension specialist Kaan Kurtural. (Photo courtesy Event Kilmartin, the University of California) In the 10 years since grapevine red blotch virus was first detected in the Napa region of California, it’s become the top threat to vineyards in the region. Infected vines produce poor quality fruit, so growers have tried delaying harvest to see […]