Effect of rootstock and preplant fumigation on plant parasitic nematode development in Washington wine grapes

Abstract

Context and purpose of the study – In Washington State, the majority of winegrape (Vitis vinifera) vineyards are planted to their own roots. This practice is possible due to the lack of established phylloxera populations, and is preferred due to the ease of retraining after damaging winter cold events. However, own-rooted V. vinifera is generally susceptible to most plant parasitic nematodes that attack grape. In Washington State, management of nematodes is dominated by preplant soil fumigation. One practice that may mitigate economic loss due to nematodes is the adoption of nematode-“resistant” rootstocks. There is little information on the performance of most rootstocks against northern root-knot nematode (Meloidogyne hapla), the main plant-parasitic nematode species in the state, and even less information on dual performance against dagger nematode (Xiphinema sp.).

Material and methods – Partnering with a commercial vineyard, we established a 3 hectare, long-term trial evaluating currently-available rootstocks in 2015, with the intent to continue the trial through vineyard establishment to vineyard production maturity (until 2025). This vineyard was undergoing replanting after 20+ years of production in own-rooted V. vinifera ‘Chardonnay’; the intent of the replant was to maintain vineyard infrastructure, but to manage for plant parasitic nematodes. The rootstocks being evaluated are: 101-14 Mtg, 1103 P, Harmony, Teleki 5C, an own-rooted control, and a self-grafted control. The scion is Chardonnay. All vines were certified through the Washington State Department of Agriculture’s certification program. The rootstock treatments were planted in 4 replicated plots of soil treatments consisting of fumigated (metam sodium through the existing drip irrigation lines), nonfumigated, and nonfumigated inoculated with M. hapla, creating low, moderate, and high nematode pressure locations under which to evaluate rootstock performance.

Results – Preplant fumigation was only effective at reducing M. hapla population densities for the first 6 months after application, yet it reduced densities of Xiphinema for 2 growing seasons. Rootstocks were poor hosts for M. hapla relative to own-rooted V. vinifera, but all were acceptable hosts for Xiphinema sp. Several rootstocks (e.g., Harmony, 101-14, 1103 P) had greater shoot biomass at the end of year 3 (end of the establishment period) compared to own-rooted V. vinifera, indicating that longer-term impacts on vigor is likely a primary driver behind the resistance phenotype these rootstocks impart under nematode feeding pressure. The goal of this project is to understand the long-term performance of rootstocks and the impacts of nematodes on vineyard lifespan in Washington State.