Irrigation and Rootstocks to Manage Northern Root-Knot Nematode During Wine Grape Vineyard Establishment

Abstract

Vineyard replanting in Washington state can be negatively impacted by the plant-parasitic nematode Meloidogyne hapla. Chemically focused nematode management programs do not offer long-term suppression; however, this may be achieved through the adoption of cultural approaches such as rootstocks and irrigation. Nematode-resistant rootstocks are used extensively in other regions but many have not been tested against M. hapla. Vineyards in eastern Washington are irrigated; therefore, manipulating available soil water may also impact nematode development. In 2017, two field trials were established in eastern Washington to evaluate the effects of (i) late-summer water limitation on M. hapla population development and (ii) host status of 1103 Paulsen, 3309 Couderc, and Matador rootstocks for M. hapla. The efficacy of these cultural management approaches was evaluated under three initial M. hapla densities (0, 50, and 250 M. hapla second-stage juveniles per 250 g of soil) in both trials. Reducing irrigation to manage M. hapla infestation of grape roots was ineffective and may cause harm to the vines by inducing too much water stress. Conversely, rootstocks effectively reduced population densities of M. hapla. Overall, rootstocks show the most promise as a cultural tool to manage M. hapla during the establishment phase in Washington vineyards.