Foundation Plant Services (FPS) operates under a “Test-to-Order” policy for grapevine material, implemented in 2018 in response to the detection of grapevine red blotch virus (GRBV) at the Russell Ranch and Classic Foundation vineyards. In addition to the annual late-summer screening of each individual Classic Foundation Vineyard vine, every vine that is used for dormant material distribution is tested again in the winter. To minimize the risk of false negatives, a total of twelve canes are sampled from each vine; six from each side. Cuttings from each Classic Foundation Vineyard vine that was the source of dormant material distributed in 2025 were re-tested for grapevine leafroll-associated virus 3 (GLRaV-3) and GRBV, with NO virus detected.
In November 2024 FPS shared the news that GLRaV-3 had been detected in one vine during the annual all-vine testing of the Classic Foundation Vineyard. The vine was removed, and the nearby vines intensively sampled for follow-up testing. In addition to screening dormant cuttings from all ordered vines this winter, the vines around the GLRaV-3 positive vine were tested again, with no GLRaV-3 detected. Monitoring of the surrounding vines will continue through the summer.
