Effect of irrigation systems, partial root zone drying irrigation and regulated deficit, on plant parasitic nematode populations in grapevine

[Truncated abstract] Nematodes are known to significantly affect productivity of grapevines worldwide. Although major surveys have been carried out on nematodes infesting roots of grapevines elsewhere, only a preliminary survey has been carried out in Western Australia (W.A.). This study on the effect of irrigation systems on pathogenicity of nematodes on vines commenced with a survey of nematodes in two major grapegrowing regions of W.A. In this survey, soil samples were taken from 5 vineyards from Margaret River and 7 vineyards from Swan Valley regions of the state. Root-knot nematode (Meloidogyne spp.) was found to be the dominant genus in both major grape growing regions. Meloidogyne spp. occurred 76% and 75% of total soil sample in Margaret River and Swan Valley. The highest density of Meloidogyne spp. was 7 nematodes/g soil in Margaret River and 3.17 nematodes/g soil in Swan Valley. In both regions, other plant parasitic nematodes were recorded that included the root lesion (Pratylenchus spp.), dagger (Xiphinema spp.) and stubby (Trichodorus spp.) nematodes. Paratylenchus spp. were found in a few soil samples from Margaret River region, and Helicotylenchus spp. were found only in Swan Valley region, but was widespread. Some vineyards have established only resistant cultivars (Schartzman, Ramsey and 34 EM) resistant to nematodes. In these vineyards total nematode population was lower than most of other vineyards. However, in comparison of nematode numbers between cultivars, there were lower number of nematodes in some susceptible cultivars than in the resistant cultivars. Most common nematode taxa were Meloidogyne, Pratylenchus and Xiphinema in both regions. Root-knot and root lesion nematodes were the most widespread and economically important genera. These two genera are known to have different life cycle and feeding habits.