Final Report – Funding Cycles 2020-2024 (includes one-year no cost extension)
Principal Investigator: Michelle Moyer, Washington State University, Prosser
Contact: michelle.moyer@wsu.edu
Co-PI’s/Collaborators: Inga Zasada, USDA-Agriculture Research Service, Corvallis; Paul Schreiner, USDA-ARS, Corvallis; Julie Tarara, Ste. Michelle Wine Estates, Paterson, and Michael Cerio, Terlato Group, Klipsun Vineyards, Benton City
Summary: This research evaluated several alternative approaches for nematode management in Washington State wine grape vineyards, including continued monitoring of a long-term rootstock block at a commercial vineyard; short-term monitoring of a smaller rootstock trial at another vineyard; field and greenhouse evaluations of different cover crops that could serve in a pre- and post-plant management approach; and a grower survey of fallow ground practices to determine their potential impact on the survival of the northern root-knot nematode (Meloidogyne hapla).
The research team’s decade-long research effort has shown that rootstocks continue to out-perform own-rooted vines in terms of sustained vine productivity when grown under the presence of relatively high nematode pressure, but they are hosts for nematodes. This indicates that the effects of high nematode pressure near the end of a vineyard lifespan, even if the vineyard is on rootstock, might need mitigation with alternative nematode management options, or through reduced vineyard stress (e.g., greater monitoring of drought stress, nutrient deficiencies). In the project’s cover crop research, it was found that litchi tomato effectively reduced northern root-knot nematode during the season the litchi tomato was planted; however, litchi tomato can only be used as a preplant cover crop. Other cover crops, such as specific cultivars of oilseed (daikon) radish worked well at suppressing nematode development and can be used in established vineyards. It appears that keeping a vineyard in a fallow state for at least 1 year is beneficial in reducing northern root-knot nematode populations in the soil.
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