073: Soil Nutrient Interactions and the Role of Potassium in Eastern Vineyards with Dr. Jaclyn Fiola
Release Date: 06/10/2025
090: Old Vines and Argentina's Ungrafted Massale Selection with Dr. Laura Catena
Vineyard Underground
Some of the world’s most valuable vineyard lessons are rooted in vines that predate modern viticulture. In this conversation, we are joined by Dr. Laura Catena to explore Argentina’s remarkable legacy of old, ungrafted vines and what they reveal about vine genetics, site expression, and long-term resilience. Drawing on her experience, Dr. Catena explains why phylloxera never devastated many Argentine vineyards and how this unique history allowed ancient vine material to survive. The discussion dives into massale selection from old vines, highlighting why genetic diversity matters —...
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089: Red Flags for Planting a Vineyard with Dr. Mark Greenspan
Vineyard Underground
Planting a vineyard is a major investment, and the decisions made before the first vine goes into the ground can determine long-term success or costly failure. In this episode, Fritz sits down with renowned viticulture expert Dr. Mark Greenspan to unpack the most common red flags vineyard owners and operators should watch for when planning a new planting. Drawing on more than three decades of scientific research and hands-on field experience, Dr. Greenspan explains why many vineyard problems originate long before planting day. Fritz and Dr. Greenspan also discuss the dangers of relying on...
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088: Pruning Q&A with Fritz Westover
Vineyard Underground
Pruning is one of the most influential decisions vineyard owners and operators make each season, and in this solo Q&A episode, Fritz tackles the most common — and most misunderstood — questions he hears in the field. Drawing on hands-on experience, Fritz walks listeners through the practical realities of dormant pruning, why it matters far beyond vine appearance, and how pruning choices directly impact vine balance, yield, and long-term vineyard health. Throughout the episode, Fritz addresses real-world concerns from growers, including how aggressive pruning should be, what mistakes...
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087: Mothballing a Vineyard - What Growers Need to Know with Dr. Christopher Chen
Vineyard Underground
A topic that many growers consider but few understand is mothballing a vineyard. In this episode, Fritz covers it all with Dr. Christopher Chen, Integrated Vineyard Systems Advisor with the University of California Cooperative Extension. With economic pressures, market shifts, and operational challenges affecting vineyard owners across the industry, temporarily idling a vineyard can feel like a practical option — but it comes with important agronomic, legal, and financial considerations. Dr. Chen brings a research-based, boots-on-the-ground perspective to the conversation, helping listeners...
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086: Viticulturists vs AI with Dr. Justin Scheiner
Vineyard Underground
Growers are turning to AI for vineyard advice — but what happens when the algorithms get it wrong? In this episode, Fritz sits down with Texas A&M Extension Viticulture Specialist Dr. Justin Scheiner to put artificial intelligence to the test and reveal where it helps…and where it falls flat. Fritz and Justin walk through real vineyard questions — on pruning cuts, choosing between cane and spur pruning, designing an effective spray program, and diagnosing puzzling leaf symptoms — then grade the answers provided by AI tools like ChatGPT and Copilot. Justin explains why, despite its...
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085: Development of the Monterey County Wine Industry with Larry Bettiga
Vineyard Underground
Fritz welcomes longtime colleague and respected viticulture authority Larry Bettiga in this episode for an in-depth look at the evolution of Monterey County’s wine industry. With more than four decades of experience, Larry offers a rare, firsthand perspective on how the region transformed from scattered early vineyards into one of the country’s most significant cool-climate grape-growing areas. Larry explains how Monterey’s dramatic coastal influence, daily wind patterns, and diverse soils shaped both the opportunities and challenges for growers. He and Fritz unpack the early years of...
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084: Damage Control - Voles & Other Vertebrate Pests with Kelly Mulville & Newt Wimer
Vineyard Underground
Voles, gophers, and ground squirrels are more than a nuisance — they can devastate vineyards if left unchecked. In this episode, host Fritz Westover sits down with Kelly Mulville of Paicines Ranch and Newt Wimer, an agricultural innovator, to discuss practical, sustainable ways to manage these vertebrate pests. Kelly shares his firsthand experience with a sudden vole outbreak at Paicines Ranch — one of the worst he’s ever seen — and explains how quickly the damage escalated. He walks through the telltale signs of vole damage, how girdling kills vines, and why population cycles and...
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083: Plan My Vineyard with Callil Capuozzo
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In this episode, Fritz sits down with Callil Capuozzo, the founder and owner of Overhead Vineyards in coastal Rhode Island. Callil shares his unique journey from industrial designer to vineyard owner and walks through the challenges of starting a vineyard on existing farmland. The conversation explores the critical early decisions in vineyard development — from soil sampling and drainage considerations to choosing trellis systems that suit humid, fog-prone climates. Callil’s experiment with a pergola-style trellis, inspired by traditional Albarino vineyards in Rías Baixas, Spain, sparks a...
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082: How Vines are Made with Dustin Hooper
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In this episode of Vineyard Underground, Fritz welcomes Dustin Hooper, Vice President of Sales at Sunridge Nurseries, to take listeners behind the scenes of how grapevines are made. While growers see the final product when vines arrive at their vineyard, there’s a fascinating process that begins long before planting — starting with certified mother vines and continuing through propagation, grafting, greenhouse production, and certification. Dustin shares his personal journey into the nursery business and offers an insider’s perspective on the complexities of producing clean, reliable...
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081: Transitioning from Grape Grower to Winemaker with Jim Duane – Part 2
Vineyard Underground
In this episode of Vineyard Underground, Fritz continues his conversation with winemaker and Inside Winemaking podcast host Jim Duane on what it takes for grape growers to successfully step into winemaking. Following part one, which covered equipment, compliance, and basic chemistry, part two dives deeper into the realities of balancing vineyard management with winery responsibilities. Fritz and Jim explore how harvest decisions shift when you’re making wine from your own fruit, weighing risks like weather and pests against the pursuit of higher quality. Jim shares how winemakers must...
info_outlineIn this episode of Vineyard Underground, Fritz welcomes soil scientist Dr. Jaclyn Fiola for an in-depth discussion on one of viticulture’s most misunderstood nutrients — potassium. Drawing from her recent research and extensive fieldwork across the Mid-Atlantic region, Jaclyn breaks down how potassium behaves differently from other macronutrients, where it originates in the soil, and what makes its availability so complex for grape growers.
Fritz and Jaclyn explore why vineyards in the Eastern U.S. often see discrepancies between soil and tissue potassium levels and how that can impact grape quality, vine health, and ultimately wine pH. They dive into the implications of both potassium deficiency and excess, emphasizing how water availability and soil mineralogy play pivotal roles in potassium uptake. Growers will also learn why standard soil tests may not give the full picture — and why plant tissue testing, particularly whole-leaf sampling at veraison, is often more reliable.
Jaclyn shares the results of her groundbreaking study, highlighting best practices for sampling, how to interpret potassium levels accurately, and actionable steps for managing young versus mature vines. Whether you're planting a new vineyard or managing high potassium levels in an existing one, this episode equips you with the tools to make more informed nutrient management decisions.
In this episode, you will hear:
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Potassium largely comes from soil parent material, not organic matter, making it harder to assess with traditional testing.
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Moisture-rich soils increase potassium availability, especially in non-irrigated Eastern vineyards.
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Whole-leaf tissue testing at veraison gives the most accurate indication of potassium status in grapevines.
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Too much potassium can raise wine pH, affecting mouthfeel, color, and shelf life.
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Before applying potassium fertilizers, understand your soil minerals and use targeted tissue testing to avoid overcorrection.
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Resources:
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If you are starting a vineyard or thinking about starting a vineyard, apply to be on the podcast for Fritz’s help planning your vineyard - https://www.vineyardundergroundpodcast.com/contact/
Today’s Guest:
Dr. Jaclyn Fiola is a soil scientist who specializes in vineyard soils and soil science pedagogy. She works as an Assistant Professor of Soil and Environmental Science at Delaware Valley University.
Connect with Jaclyn, follow her, and view her research.
Episode Sponsor:
Today’s episode was brought to you by Vigneron Toy Store and the Inside Winemaking podcast.
Thank you to Vigneron Toy Store for sponsoring today’s episode. Vigneron Toy Store specializes in Harvesters, Sprayers, Frost Mitigation Equipment, Canopy Management Trimmers, and more. As grape growers themselves, they can expertly help you determine the best equipment for your specific vineyard needs. And, as a special offer for our podcast listeners, you can save 5% off in-stock machines by entering the promo code Underground on the contact form at vignerontoystore.com.
Thank you to the Inside Winemaking podcast for sponsoring today’s episode. To learn more about the art & science of winemaking with Jim Duane, visit www.insidewinemaking.com/ and listen to the Inside Winemaking podcast on your favorite podcast app with new episodes releasing every other Tuesday.
Episode Credits
If you like this podcast and are thinking of creating your own, consider talking to my producer, Emerald City Productions. They helped me grow and produce the podcast you are listening to right now. Find out more at https://emeraldcitypro.com. Let them know we sent you.