Plant-Parasitic Nematodes Associated with Grapevines, Vitis vinifera, in Oregon Vineyards.

A survey of vineyards in western Oregon was conducted in 1994 and 1995 to determine the association of plant-parasitic nematodes with vine health. Seventy vineyards in four regions of western Oregon (16 to 21 vineyards per region) were sampled. The regions were the northern, middle, and southern Willamette Valley, and southern Oregon. Vineyards were selected and partitioned into blocks by variety, age of planting, crop history, and soil characteristics. Mesocriconema xenoplax, Xiphinema americanum, Pratylenchus spp., and Paratylenchus spp. were recovered from more than 85% of the vineyards; only 10% of vineyards had detectable populations of Meloidogyne hapla. Mesocriconema xenoplax and X. americanum were found in 20% and 8% of vineyard blocks, respectively, at population densities reported to cause moderate yield loss in California. Mesocriconema xenoplax was found at greatest population densities in vineyards older than 10 years and on former Prunus orchard sites in the northern Willamette Valley. Populations of Mesocriconema xenoplax and X. americanum were associated with both healthy and stunted vines. The long-term impact of M. xenoplax, X. americanum, and other nematodes on Oregon vineyard production has not yet been determined.