In this episode of Trellis Talks, host Caleb Mosley reconnects with phenolics researcher James Campbell, now based in Napa Valley and leading a lab focused on vineyard and wine phenolic analysis. Their conversation explores the science behind phenolic development in wine grapes, from early-stage flavonol formation to anthocyanin synthesis and degradation. James emphasizes the importance of early-season practices—like precise leafing and light management—and shares findings from multi-year studies on the effects of heat and irrigation on phenolic preservation. One key insight is that applying moderate irrigation during mid-ripening heat waves can mitigate anthocyanin loss, but late-season interventions are often too late to make a difference.
​
The discussion also touches on the nuanced interplay of variety, environment, and stress, noting that different grape cultivars respond uniquely to heat. James shares that Cabernet Sauvignon shows higher resilience compared to varieties like Sangiovese. The episode concludes with a look into James’s new venture, Integrated Phenolics, which offers rapid, in-depth phenolic assays for growers and winemakers. His goal is to equip producers with actionable data to make informed decisions during maceration and fermentation, ultimately supporting the continued excellence of Napa Valley wines in a changing climate.

In this episode of Grown in Napa Valley, NVG celebrates its 50th Anniversary by honoring two influential figures who shaped—and continue to shape—Napa Valley’s viticultural legacy. The episode begins with a rich conversation with Andy Beckstoffer, one of NVG’s founders, who shares the story behind the organization's creation and the pivotal moments that helped elevate grape growers from second-class status to key decision-makers in the wine industry. From advocating for the 75% appellation rule to establishing vineyard-designate branding, Beckstoffer reflects on the early battles for grower respect, the transition from commodity farming to quality-driven practices, and how the region found confidence in its own identity following the 1976 Judgment of Paris.

Then, we share a glass with the 2025 Grower of the Year Oscar Renteria, who reflects on his upbringing in a multi-generational farmworker family and his journey toward leading Renteria Vineyard Management. Oscar speaks with heartfelt optimism about resilience, legacy, and mentorship, emphasizing the importance of education, cultural pride, and finding joy in hard work. His leadership style—rooted in gratitude, empathy, and teamwork—embodies NVG’s mission and offers a forward-looking perspective for the next generation of Napa growers navigating uncertain times with hope and purpose.

• “The background of the formation of the Grape Growers was respect. We wanted respect as growers—and that changed everything.” – Andy Beckstoffer
• “The vineyard brand can be more valuable than the winery brand—if you market your vineyard, not just sell your grapes.” – Andy Beckstoffer
• “I came back to Napa not because I had to—but because I saw the beauty, the legacy, and the chance to build something meaningful with my father.” – Oscar Renteria
• “I find the most fulfillment in mentoring others—helping people grow is how I measure success today.” – Oscar Renteria
• “The mantra is ‘wine is grown in the vineyard’—but for too long, the value wasn’t passed through to the grower. That changed here in Napa.” – Caleb Mosley
• “We're celebrating 50 years of grit, collaboration, and excellence—and the people who made Napa Valley what it is today.” – Caleb Mosley