Field Response of Rootstocks to Northern Root-Knot Nematode
Michelle Moyer,* Maria Mireles, Katherine East,
Bernadette Gagnier, and Inga Zasada
*Washington State University, 24106 North Bunn Rd, Prosser, WA,
99350 (michelle.moyer@wsu.edu)
Management of plant parasitic nematodes in Washington State vineyards undergoing replanting has been dominated by preplant soil fumigation. Our past work showed this approach does not result in long-term suppression. In 2015, we established a trial evaluating rootstocks in a commercial vineyard undergoing replanting after 20+ years of production. The rootstocks were planted in replicated plots of fumigated (metam sodium), nonfumigated, and nonfumigated inoculated with Meloidogyne hapla (northern root knot nematode). By fall 2021, all evaluated non-vinifera “resistant” rootstocks (101-14 MGT, 1103P, Harmony, Teleki 5C) supported M. hapla development; however, Teleki 5C and 1103P supported fewer M. hapla than the own-rooted Vitis vinifera control vines (eightfold fewer nematodes; p = 0.02). While not statistically different than own-rooted V. vinifera, Harmony and 101-14 MGT supported threefold fewer nematodes. When considering the multi-year chronic exposure to M. hapla (nematode dosage), all evaluated rootstocks had reduced M. hapla dosage than own-rooted V. vinifera. This M. hapla dosage comparison also provides a means to visualize nematode “tolerance”: 1103P and Teleki 5C supported the fewest M. hapla over time, followed by Harmony and 101-14 MGT, with own-rooted V. vinifera supporting significantly more M. hapla over time (p < 0.0001). The rootstocks evaluated in this study had heavier pruning weights than own-rooted V. vinifera after three growing seasons (p < 0.0001). Among the non-vinifera rootstocks, some supported more nematodes than others, but after seven growing seasons, there was not a statistical difference between rootstock choice and influence on dormant pruning weights (p < 0.05). This enforces the concept of tolerance: though a rootstock might support M. hapla development, there is not a discernable phenotype difference. The use of non-vinifera rootstocks, while still supporting some M. hapla development, are still a sustainable long-term solution for M. hapla management.
Funding Support: 80% Washington State Grape and Wine Research Program, 10% USDA National Institute of Food and Agriculture, Hatch project #1016563, 10% USDA-ARS Current Research Information System 2072-22000-043-00D
