Susceptibility of melon cultivars to Meloidogyne incognita and suppression by biocontrol agents

Abstract

Abstract: Melon (Cucumis melo L.) is widely consumed and among the most exported fresh fruits of Brazil. Despite substantial production, this crop is limited by several factors, notably the root-knot nematode Meloidogyne incognita, for which few management tools are available. In our work, we assessed the host status of ten different melon genotypes, from which we selected ‘Asturia’ for subsequent biocontrol experiments. We then evaluated the efficacy of Bacillus amyloliquefaciens, Pochonia chlamydosporia (i.e., Rizotec®), and Purpureocillium lilacinum twice against M. incognita, and, finally, we conducted a dose–response experiment using Rizotec® to determine its performance across application rates. All genotypes were susceptible. Regarding biocontrol, P. lilacinum significantly reduced nematodes per gram of root when applied once, compared with two applications for P. chlamydosporia. Regarding dose-response, increasing doses presented a strong negative correlation with final population size, with the EC50 estimated at 0.84 plant-1. In addition to reducing the nematode population, dosages also increased fresh weight, fruit weight, and stem diameter at themiddle and top of the plant. However, they only did so in the inoculated plants.Pochonia chlamydosporia (i.e, Rizotec) represents a potential strategy for the management of M. incognita and should be integrated with additional management practices to enhance its efficiency.