Virologists Recommend Re-Evaluation of Regulated Grapevine Viruses

The exchange of grapevine propagation material across geographic and regulatory boundaries increases the diversity of cultivars and rootstocks available to the grape and wine industries but also risks the dissemination of pests and detrimental pathogens such as viruses in new grape production areas. Therefore, regulations are established to facilitate the safe trade of propagation material with desirable traits and to safeguard vineyard health. Sometimes regulations are inadequate, thus unduly delaying the accessibility of desired germplasm for growers and providing motivation for illegally introducing germplasm of interest. To address some of the regulatory limitations, scientists from around the world recently defined phantom agents. These are pathogens for which neither reference material nor nucleotide sequences are available, making it impossible to diagnose such agents in grapevine and other fruit crops.

This scenario provided a compelling case for excluding such pathogens from regulatory oversight (Tzanetakis et al. 2024). At the same time, a group of virologists realized the need to complement the list of phantom agents in grapevines and recommended excluding nine viruses, 14 virus-like diseases and nine viroids from regulation (Fuchs et al. 2025). The pathogens and diseases are not known or are not suspected to have any substantial detrimental impact on vine health. Collectively, these recommendations are anticipated to serve as a solid foundation for facilitating an informed dialogue with federal and state policy makers, and to result in more streamlined regulations for expediting the safe exchange of grapevine germplasm while reducing incentives for illicit introductions. Adopting these recommendations will substantially reduce the list of target pathogens for diagnostics and therapeutics at Clean Plant Centers of the NCPN-Grapes, thus optimizing resources and contributing to the NCPN sustainability.