PLANT-PARASITIC NEMATODES IN CHILEAN VINEYARDS

A survey to detect the presence and distribution of plant-parasitic nematodes in Chilean vineyards was undertaken during the years 2006 and 2007 covering an area of 40000 km 2, over 90% of the surface area cultivated with Vitis vinifera L. Descriptive statistics relative to the distribution observed, number of nematodes per taxa and sample was performed. Correspondence analysis and canonical correspondence analysis were performed to determine relations between nematodes taxa with cultivars and soil type. Twelve nematode genera were extracted from 1818 soil samples, but only four were considered to be highly pathogenic to the crop, Xiphinema spp. (X. index, X. americanum sensu lato), Meloidogyne spp. (M. ethiopica, M. spp.), Mesocriconema (M. xenoplax) and Tylenchulus (T. semipenetrans). The population densities of determined taxa were fairly variable; however, at least one of the species was present in every sample in high density. No correlations between nematode species were observed, nor was there a tendency of two or more nematodes to occur together. The total variance of nematodes was only marginally explained by cultivars and soil with an incidence of 18% and 0.5%, respectively, and an unexplained variation of 81.3%. These data indicated that environmental factors or management practices not measured in the survey greatly influenced nematode populations, and that previous selection of the variables to be evaluated should include some of them, like irrigation, tillage or fertilizers, especially under intensive agriculture.