Actionable Takeaways for Growers from the 2024 ROOTSTOCK Conference

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:
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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.