Susceptibility of Vitis vinifera 'Semillon' and 'Chardonnay' to the root-knot nematode Meloidogyne javanica

A study to assess the effect of the initial population (Pi) densities (0, 200, 400, 600 and 800 second stage juveniles (J2) kg-1 dry soil) of the root knot nematode, Meloidogyne javanica, on the growth, yield and juice characteristics of two white wine grapevine (Vitis vinifera) cvs. Semillon and Chardonnay was conducted in a vineyard located at the Centre for Irrigated Agriculture, Riverina, NSW, Australia. M. javanica J2 population densities in soil after harvest during 2004-2008 growing seasons increased gradually, year by year, and in most cases were higher where the initial densities were higher. Regression analysis revealed that yield, in general, was reduced significantly with the increase of the nematode population densities kg-1 soil for both cultivars. After six years, the nematode population had increased by ca. 9.0 -22.4 fold for Semillon and 6.7 -18.5 fold for Chardonnay. All Pi densities significantly reduced Semillon yields in all years but only the highest level (800 J2 kg-1 dry soil) affected Chardonnay yields. At the end of the experiment, M. javanica decreased yields by 15-20% in Semillon but only 7-13% in Chardonnay. The nematode inoculation also caused a decrease in bunch numbers in Semillon but not in Chardonnay. This is the first study showing that Chardonnay is less susceptible to M. javanica than Semillon.