In this episode of Grown in Napa Valley, host Caleb Mosley sits down with two influential women in the Napa Valley wine industry, both leading their own successful businesses.

First, Dr. Kris Lowe, owner of Vine Balance Consulting and a leader in vineyard research funding, discusses the vital role of research in combating vineyard diseases like Pierce’s disease and red blotch. She also explains the upcoming PDGWIS Board funding referendum and why grower participation is essential for Napa Valley’s future.

Next, Caleb chats with Brittany Pederson, founder of Vintuition, a viticulture consulting company. Brittany shares her career journey, insights into vineyard management, and the challenges and opportunities of being a woman in the wine industry. As they chat, they enjoy a glass of 2015 Phifer Pavitt Cabernet Sauvignon Date Night.

Join us for an engaging conversation filled with expertise, personal stories, and a shared passion for Napa Valley’s grape-growing community.

RESOURCES:
California Department of Food and Agriculture 
National Academies 
NVG ROOTSTOCK: New Research and Trends with Marc Fuchs 

The 2024 ROOTSTOCK Conference emphasized actionable strategies for managing Red Blotch Virus (RBD), improving pest control, and fostering collaboration. Here are the key points growers can implement now:
​
1. Understand the Unique Nature of Red Blotch Virus

• Red Blotch is unlike any other virus in viticulture; comparisons to existing mitigation efforts have proven ineffective for analysis and control. Continued research and experimentation are essential for effective management.
• Address Critical Challenges:
  • The virus has an extensive latent period before symptoms appear.
  • Its distribution within vine tissues is extremely uneven. These issues complicate scouting, sampling, testing, and rogueing programs.

2. Adopt Targeted Rogueing and Replanting Strategies

• Zonal Rogueing: Removing only symptomatic vines year after year is insufficient. Instead, adopt zonal rogueing strategies to account for asymptomatic but infected vines by removing adjacent plants within a certain radius depending on the dynamics of the disease spread within your vineyard.
• Coordinate Replanting: Whenever possible, coordinate large-scale replanting efforts with neighboring vineyards. A community-level commitment to addressing Red Blotch is key to success. Remember, Sauvignon Blanc and white varieties can still harbor the disease and serve as an inoculum source for adjacent vineyards. 

3. Monitor Virus Spread Dynamics

• Two patterns of Red Blotch spread have emerged:
  • Concentrated Spread: Linked to infected planting material, leading to clusters of infected vines.
  • Diffuse Spread: In vineyards without infected plant material, the virus spreads less densely, resulting in lower annual infection rates.
• Drought and Vector Activity: Excessive drought correlates with increased feeding and virus transmission by the Three-Cornered Alfalfa Hopper (TCAH). The 2024 season highlighted a rise in newly symptomatic vines due to heightened TCAH activity during previous dry periods in 2020 and 2021.

4. Prioritize Testing, Mapping, and Monitoring

• Implement proactive testing and mapping to detect asymptomatic infections early.
  
• Due to the uneven distribution of the virus within the plant, it's essential that visual scouting accompanies testing programs. 
• Use visual year-over-year mapping to demonstrate trends and justify resource allocation to stakeholders.

5. Foster Collaboration and Communication

• Invest in neighborly relations to develop regional Red Blotch management strategies. Success depends on trust, open communication, and shared commitments.
• Align internal vineyard teams on the financial and operational impact of Red Blotch to ensure unified decision-making before engaging in community-wide efforts.

6. Adapt Vineyard Practices to Improve Wine Quality

• Harvest fruit at different ripeness levels to optimize unaffected clusters, though be mindful of logistical costs.
• Petit Verdot can be used in co-fermentation to enhance the structure and color of virus-affected wines.

​By implementing these actionable strategies—rooted in collaboration, targeted rogueing, and proactive monitoring—growers can mitigate the impacts of Red Blotch Virus and develop long-term solutions to sustain vineyard health.

On Tuesday, August 6, 2024, an adult male Oriental Fruit Fly (Bactrocera dorsalis) was detected in a pest detection trap in Sonoma County, just outside the town of Sonoma. The trap, located in a fruit tree on a residential property near 8th Street East and Old Winery Road, caught the attention of the California Department of Food and Agriculture (CDFA) and local county agricultural departments. While the discovery of a single fly does not immediately trigger a quarantine, it does call for increased fruit fly trapping and monitoring, which in this case, extends into parts of Napa County.

In response to this finding, Sonoma County Ag, Napa County Ag, and CDFA are collaborating to place additional delimitation traps around the core area of the detection. Over the next week, 425-450 traps will be deployed within a 4.5-mile radius, covering parts of southwest Napa County, including areas around Redwood Road, Partrick Road, Mt. Veeder Road, and the western section of Carneros. CDFA staff began placing traps on August 9 and 10, primarily in residential and roadside host trees, with the goal of ensuring no further adult flies are found, thereby avoiding a quarantine. So far, CDFA has successfully treated the initial find site and adjacent properties in Sonoma County.

As of today, all delimitation traps have been successfully deployed around the find site, encompassing the core area (1 square mile), the first buffer zone (9 square miles), and the outer buffer zones (16-32 square miles). These traps have been checked and serviced multiple times. Initially, daily checks were conducted during the first week. With no additional findings, the frequency of servicing has been reduced to weekly, starting August 19. Currently, 222 traps are set in Sonoma County and 62 in Napa County. CDFA staff will continue their trapping activities throughout the delimitation process.

It’s important to note that last year saw an unprecedented number of exotic fruit fly detections and active quarantines in California. Fortunately, all seven fruit fly quarantines last season, including those in nearby counties like Sacramento, Contra Costa, and Santa Clara, successfully eradicated the pest populations, allowing the quarantines to be lifted. This serves as a reminder of the importance of ongoing pest exclusion and detection efforts to protect our agricultural communities.

Growers within the delimitation area in Napa have been notified, but it’s important to stress that there is currently no quarantine in place, so vineyard and winery operations can proceed as usual. We remain vigilant and committed to safeguarding our agricultural lands from invasive species and ensuring that Napa’s renowned wine industry remains unaffected by these potential threats. Stay tuned for further updates as we continue to monitor the situation closely.

​You may have heard by now of an invasive insect pest called the spotted lanternfly (Lycorma delicatula). This damaging pest was found in Pennsylvania in 2014 and has established itself in 17 states since then. It is native to Asia, where it lives in balance with population controls such as parasitic wasps and other predators. Here in the United States, no such controls exist, and the population expands rapidly. The spotted lanternfly (SLF) has done serious damage to vineyards. The story of SLF is intertwined with a particular tree species, also endemic to Asia. The tree of heaven (Ailanthus altissima) is a favored host of SLF, and some researchers point to growing evidence of a dependent relationship between the insect and this prolifically spreading tree. Unfortunately, tree of heaven (TOH) was deliberately introduced to the United States in the 1700’s as an extremely hardy and fast-growing ornamental species.

There are many established stands of TOH here in Napa that will provide prime habitat for SLF in the event the pest is introduced here. Some of these TOH populations are directly adjacent to vineyards, increasing the risk of SLF infestation. It is not likely that a weak flyer like SLF would ever expand its range westward through the many geographic barriers it would face. Rather, this pest will likely make it debut into California as a hitchhiker on a plane, in a car, or as egg masses attached to objects in transfer from infested areas. For this reason, California Border Inspection Stations are on high alert to detect SLF egg masses. Because the SLF threat is so severe, the California Department of Food and Agriculture has established an action plan to facilitate rapid response.

The Napa County Agricultural Commissioner’s Office (CAC) has been closely monitoring the SLF/TOH connection and threat potential. Along with plenty of public outreach and education materials, we have been placing SLF detection traps throughout the county since 2020. Very few other counties has actively trapped for this pest. The traps are located in areas of highest risk, including adjacent to vineyards, storage and shipping facilities, rail lines, the airport, and campgrounds. Along with a detection trapping program, we have done a thorough survey of the county, mapping the location of TOH individuals and sapling clusters. This work was made possible by initial grant funding from the State, and on-going funding from the Winegrape Pest and Disease Control District. Napa CAC also inspects all plant material entering the county, along with inspections of materials moved here from high-risk areas. These inspections also look for the egg masses of the Spongy Moth, formerly known as the Gypsy Moth. The Napa CAC will remain vigilant and proactive in facing the double threat of TOH and SLF.

If this information has made you want to take action yourself, we’d like to ask for your help in identifying more TOH specimens for a mapping project that allows us to prioritize locations for detection trapping and outreach. Please participate in our survey to help you identify TOH. 

The Napa Valley Grapegrowers announces ROOTSTOCK 2023, to be held on November 6 and 7 at the Napa Valley College Performing Arts Center. This year’s event will focus on a central theme: weed management in the vineyard.
 
Though weed management in the vineyard is an integral part of the vineyard management system, there is mounting pressure to adapt farming methods to navigate public perceptions. And, as Napa Valley growers continue to strive for viticultural excellence, employing innovative best practices is paramount to increasing quality and sustainability in our vineyards.
 
ROOTSTOCK 2023 is open to the public, and the Napa Valley Grapegrowers hopes the focused format will inspire discussions in an open and collaborative manner. This year’s highlights include:

• Understanding the public’s perspective on herbicides with, “Children of the Vine” director, Brian Lilla
• Review of Napa County herbicide trends with Sarah Ferguson, CEO and co-founder of Ruetd
• The history of herbicide use in vineyards and agriculture with Dr. Scott Steinmaus, PhD, head of plant sciences, California Polytechnic State University, San Luis Obispo
• A wine business case study with Ivo Jeramaz, winemaker and vice president of vineyards and production, Grgich Hills Estate
• Continuing Education Seminars (1 professional development and 2 integrated pest management CEU credits)
  • Napa County regulatory review of pesticides with the Napa County Agricultural Commissioner’s Office
  • Sustainable pest management – a roadmap for California with Nan Singhasemanon, assistant director, Department of Pesticide Regulation
  • Integrated weed management – identification, control, and innovative alternatives with John Roncoroni, weed science farm advisor, Emeritus, UC Cooperative Extension

 
Who should attend: Viticulturists, vineyard managers, winemakers, enologists, vineyard and winery owners, students, and community members interested in learning more about weed management in the vineyard.
 
Single-day and two-day ROOTSTOCK tickets can be purchased online on the Napa Valley Grapegrowers website.
 
The Napa Valley Grapegrowers hosted its first symposium and exhibition, the Napa Valley Viticultural Fair, in 1990. Now, over three decades later, ROOTSTOCK has evolved beyond a tradeshow format, yet carries on the tradition of delivering top quality education and resources to the wine industry. 

​The University of California Cooperative Extension (Napa) and Tule are building an Artificial Intelligence (AI) model to diagnose grapevine virus symptoms. Their goal is to build an app called "Virus Vision" that diagnoses Grapevine Leafroll Disease, Red Blotch Disease, and other causes of red leaves from phone camera pictures.
 
NVG members can support their app by submitting pictures and virus test results; members who contribute to the data set will receive free and early access to the mobile app.

​On Friday, October 1, 2021 a total of five glassy-winged sharpshooters (GWSS) were confirmed on two different traps in a residential part of Vacaville, in Solano County. A delimitation survey that began on Saturday, October 2 confirmed some presence of GWSS at several more sites near the initial trap found through a visual survey. All of the finds so far have been in urban, residential settings in Solano County.
 
The Solano County Agricultural Commissioner’s office & the Pierce’s Disease Control Program are working together on next steps.  The Napa County Ag Commissioner’s office will share a press release and any relevant guidance as soon as available. Current protections in place in Napa County include:

• The Ag Department continues to inspect all incoming plant shipments from out of the county, regardless of the origin nursery and its location
• GWSS urban traps and nursery traps are placed throughout the county
• We track our landscape receiving locations and place GWSS traps up within days to additionally monitor for potential pests

 
NVG will continue to work with the Napa County Ag Commissioner’s office to keep growers informed as we learn more.
 
For more general information on GWSS, visit NVG’s Pest page and Napa County’s website.