A Population of Meloidogyne javanica in Spain Virulent to the Mi Resistance Gene in Tomato.

A population of Meloidogyne javanica virulent to Mi-gene in tomato was identified in Spain. It reproduced similarly on resistant and susceptible tomato cultivars in the greenhouse, microplots, and in the field. In monoxenic cultures, reproduction of the virulent M. javanica was higher than that of an avirulent population on resistant but not on susceptible tomatoes. The virulent population suppressed tomato yield of both resistant and susceptible tomatoes by 29% in microplots. Initial population density (Pi) was inversely correlated with Pf (final population density)/Pi on both resistant and susceptible tomatoes in the field. A negative correlation was found between Pi and tomato yield for the susceptible but not for the resistant cultivar.