Abstract

In Chile, stone fruits (Prunus spp.) are mainly produced in four Chilean regions of the Central Valley (latitude 30°S-37°S), where they account for 80% of the national fruit production area. In these regions, root-knot nematodes (RKN) Meloidogyne spp. have a high economical impact and M. ethiopica is the prevalent species on many crops. The use of resistant rootstocks is one of the most economical and environmentally sound methods for managing RKN infestations. The aim of this study was to evaluate the host response of ten Prunus rootstocks: Pomona, Nemaguard, Mariana2624, CAB-6p, Gisela-6, Piku-1, Piku-4, Rootpac-90, Rootpac-20 and Rootpac-R, against six aggressive Meloidogyne isolates. These isolates, three from each M. ethiopica and M. javanica, had been rated in a previous study as the most aggressive out of 20 RKN isolates sampled in the Central Valley. Ten replicates of each rootstock were used and inoculated with 10,000 individuals (J2+eggs) containing an equal proportion of the six isolates. The infested rootstocks were grown in pots under greenhouse conditions for five months and then harvested. Numbers of galls and nematodes were counted and reproduction data were analyzed separately using a one-way analysis of variance. The host response of Prunus rootstocks was rated as follows: I = immune (absence of root galls; no nematodes in roots); HR = highly resistant (very low galling and final/initial numbers < 0.10); R = resistant (low galling; 0.10 < final/initial numbers < 1); and S = susceptible (abundant galling; final/initial numbers > 1). The rootstock Pomona was susceptible. Nemaguard and Rootpac-90 were resistant and highly resistant, respectively, whilst Mariana2624, CAB-6p, Gisela-6, Piku-1, Piku-4, Rootpac-20 and Rootpac-R were immune.