Recent Virus Discovery: Grapevine Red Blotch Disease

In November, Grapevine Red Blotch Disease was announced by University of California, Davis scientists, Mysore Sudarshana and James Wolpert. The disease was discovered after grapevines that appeared to be exhibiting symptoms of Leafroll Disease tested free of Leafroll and Rugose Wood viruses.

The symptoms include irregular red blotches on leaf blades of basal portions of shoots starting in late August, reddening of the secondary and tertiary veins, and a low Brix units. Occasionally reddening of leaf blades in the interveinal zones occurs, however, the leaf margins do not roll downward, as with Leafroll.

Symptoms appear to be associated with a unique DNA virus found in diseased Cabernet Franc, Cabernet Sauvignon, and Zinfandel vineyards. An identical virus has been found in grapevines in Canada and researchers at Cornell University have identified a similar virus in vineyards in New York and Pennsylvania.

For more information, please visit the UC Integrated Viticulture website or view the informational brochure.