Resistance and tolerance of grape rootstocks to South Australian populations of root-knot nematode

Abstract

Twenty-three grape rootstocks and four commercial varieties were screened in pots for resistance to populations of root-knot nematode from the Barossa Valley, Riverland and Southern Vales regions of South Australia. Four species (Meloidogyne arenaria, M. hapla, M. incognita and M. javanica) were present in the Barossa Valley population, while the other two populations contained only M. hapla and M. javanica. The Barossa Valley population multiplied better and produced more galls than the other populations, but the resistance of each rootstock relative to others was similar for all three nematode populations. The most resistant rootstocks were Ramsey, Dog Ridge, Freedom, Schwarzmann, 16 16, K51-32 and K51-40. Rootstocks with high or moderate nematode resistance in pots also showed good resistance in three field trials. The tolerance of each rootstock to root-knot nematode was evaluated by comparing root growth in the presence and absence of the nematode. Rootstocks with the best nematode resistance were also the most tolerant. Although variations in pathogenicity are often observed between species of Meloidogyne and within populations of the same species, we concluded that nematode resistant grape rootstocks would be useful against the range of pathogenic variation in the nematode likely to be encountered in South Australia.