1a.Objectives (from AD-416):
Provide Pacific Northwest (PNW) grape growers with more information about the damage potential and management of plant-parasitic nematode.
1b.Approach (from AD-416):
1) Screen grape variety/clone combinations against Meloidogyne hapla in the greenhouse;. 2)Determine macro and micro spatial dynamics of plant-parasitic nematodes in established PNW vineyards; and. 3)Determine the impact of M. hapla on variety/clone establishment and productivity in a field setting.
Plant-parasitic nematodes are commonly encountered in soil samples collected from Washington vineyards; however, little is known about the biology, distribution, and impact of these root parasites in the second largest grape producing region in the United States. Greenhouse and field experiments were initiated to begin to address these questions, with the end goal of providing Washington grape growers with information about plant-parasitic nematode upon which to base management decisions. In the first year of greenhouse evaluations of own-rooted grape variety/clones, it was discovered that the white varieties Chardonnay and White Riesling were better hosts to the root-knot nematode, Meloidogyne hapla, than the red varieties Syrah, Cabernet Sauvignon, and Merlot. In general, White Riesling clones were the best hosts for root-knot nematode while Merlot clones were the poorest hosts for the nematode. Also initiated during the first year of this project, was a survey of plant-parasitic nematode distribution in established vineyards. In a Chardonnay vineyard it was found that root-knot and ring, Mesocriconema xenoplax, nematode population densities were weakly to moderately related to soil moisture and fine roots. There was a trend towards root-knot nematodes being aggregated around irrigation wetting zones, while ring nematodes were aggregated around vines. These results provide the first indication that plant-parasitic nematodes may be managed in Washington vineyards through variety selection. There may also be the opportunity to target areas within a vineyard where plant-parasitic nematode populations are high during pre-plant management. This research was conducted in support of objective 303 2C: Ecology and Epidemiology of Plant Diseases.