Samie Hartley, Napa Valley Register

he Napa Valley Grapegrowers recently hosted ROOTSTOCK 2024 to discuss two viral threats to vineyard health: Leafroll Virus and Red Blotch Disease.

Difficulties mitigating the spread of both Leafroll Virus and Red Blotch Disease are causing increased concern for growers due to the reductions of fruit quality and negative impact on vineyard profitability, according to a news release. With no cure available, the importance of early detection, innovative management practices, and cutting-edge research has never been higher. ROOTSTOCK, held at Napa Valley College on Nov. 19, featured expert-led sessions and panel discussions that dove into the latest research and mitigation strategies to address these viruses.

​"Preventing the spread of red leaf viruses requires a community effort. We must all work together," said NVG Director Justin Leigon of Piña Vineyard Management. "Local neighborhood groups have been building strong social networks to foster collaboration and share experiences, and the academic community has made significant progress in understanding how red blotch spreads and has identified effective mitigation methods, such as targeted vine removal."

Standing on the precipice of its 50th anniversary, the Napa Valley Grapegrowers (NVG) remains steadfast in its mission to cultivate viticultural excellence and environmental stewardship for the Napa Valley. In 2025, the organization's work will continue to foster the future of Napa Valley's wine industry with plans to:

Educate: NVG will look at the future of farming in Napa through Ahead of the Curve, the organization's biennial program dedicated to helping grape growers address the challenges of farming, including how to reduce water use and labor costs, and increase efficiencies. The 2025 Ahead of the Curve program will feature AI and other technological advances that enable smarter farming.

​Advocate: The value of vineyards starts with awareness. NVG will continue to connect growers with the broader community through vineyard walks, farmers market booths, and through the launch of Friends of the Grapegrowers (FOG), a program featuring community-focused, educational newsletters and unique opportunities for the public to engage with Napa Valley viticulture...

Pam Strayer, Grape & Wine Magazine
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“Red blotch is not only novel,” said Cornell researcher Mark Fuchs, speaking at the Napa Grape Growers’ Rootstock conference on November 19. “Red blotch does not behave like anything else we are familiar with.

“Forget about making analogies with Pierce’s disease. Forget about making analogies with leaf roll. We have to empty our hard drive and start rewiring everything, the way we see everything, the way we think about red blotch. So, it requires a whole village to start thinking outside the box.”

Over the last 15 years, grapevine red blotch virus (GRBV) has impacted countless winegrape vines, spreading in mysterious ways with no known cure other than vine removal, which has an enormous impact on profitability. Experts recommend replanting a vineyard when GRBV has infected 30% of the vines. Typically, vintners remove individual infected vines, a challenge as the disease can take three years for vines to show symptoms.

A native of Alsace, Fuchs is professor in the School of Integrative Plant Science Plant Pathology and Plant-Microbe Biology Section at Cornell AgriTech​.