Sustainable plant-parasitic nematode management: A case study from Washington wine grapes

Abstract

Plant-parasitic nematodes are cosmopolitan pests of wine grapes with yield losses worldwide estimated at approximately 5 to 8%. Managing plant-parasitic nematodes in wine grapes is challenging due to limited availability of effective nematicides and rootstocks with simultaneous resistance to multiple nematode species. The sustainable management of plant-parasitic nematodes in wine grapes requires a multi-faceted approach that integrates vine health, nematicides, and resistance into a plan that starts prior to vineyard establishment. Decisions should be made with knowledge of nematode biology including the species present and their distribution and population dynamics. The objective of this research program is to provide wine grape growers in Washington, USA with sustainable means to manage plant-parasitic nematodes including post-plant nematicides and rootstocks. In Washington, the predominant nematode threat was identified as Meloidogyne hapla, and this nematode’s distribution in the state was determined. Within vineyard spatial and population dynamics of M. hapla were determined to allow for targeted treatment and sampling strategies. To facilitate plant material selection, the susceptibility of commonly planted own-rooted varieties was evaluated; white varieties (Chardonnay and Riesling clones) were found to be significantly better hosts for M. hapla than red varieties (Syrah and Merlot clones). Additionally, rootstocks were identified with resistance to M. hapla. Finally, the efficacy of a drip-applied fumigants and post-plant nematicides are being evaluated. Combining these management components will lead to sustainable management of M. hapla in this wine producing region of the United States.