Advancing Elite Grape Rootstocks with Reduced Nematode Susceptibility. AVF Project #2025-2669.
Summary of Final Report:
Vineyards suffer from infestations with plant-parasitic nematodes. Owed to the extended years of cropping vineyards, the soil-dwelling parasites have ample opportunities to build up and cause damage. Thus plant-parasitic nematodes can become major yield constraints. A single location is often infested by multiple species including Meloidogyne spp. (root-knot nematodes), Mescocriconema xenoplax (ring nematode), Xiphinema americanum or X. index (dagger nematode), and Tylenchulus semipenetrans (citrus nematode). The nematode species can occur in various combinations within the upper 5-ft of soil or deeper. Rootstocks will need broad-spectrum protection from multiple species if they are to be useful for nematode management. In a previous testing series using greenhouse-selected accessions under nematode-infested field conditions, twelve genotypes were selected based on their propagation characteristics, vigor under nematode-infested conditions, and yield were selected for use in a commercial-type planting. These accessions were bench-grafted to ‘Pinos Gris’ and planted in 2023. In 2023 and 2024, plant measurements were taken. At the first harvest in 2025, eight accessions yielded at a similar level as ‘Freedom’ and trended much higher than the included susceptible comparatives. These are elite accessions that should be forwarded to on-farm trialing to provide superior rootstocks to the grape industries.
This is the final report on the original project. At the original initiation of the project (2022), plants for testing were not available, and the PI requested a no-cost extension that was graciously granted by AVF for the project to start in 2023. The project was executed after this start date. This is the report on the third-year activities in this 3-year project.
The current project has been the logical expansion of the identification of multiple genotypes that are more easily propagated than prior selections and carry meaningful nematode-reducing capacities while providing plants that produce competitive yields. The original objective has been attained, and multiple promising elites that warrant on-farm testing have been identified. Keeping the need of nematode-resistant rootstocks in the discussion among stakeholders is important at times of dwindling availability of soil fumigation as a management tool.
