Assessment of rhizobacterial consortia to manage plant parasitic nematodes of grapevine

Abstract

Two of the most damaging plant parasitic nematodes affecting vineyards in Chile are Xiphinema index and Meloidogyne ethiopica, whose control is primarily performed with chemical nematicides. The aim of this study was to assess the effect of formulations based on native rhizobacterial consortia and Increasing cell concentrations on the mortality and root system damage of potted plants. The grapevine cultivar Cabernet Sauvignon grown in naturally infested soils was used. The isolates Bacillus amyloliquefaciens FR203A, B. megaterium FB133M, B. thuringiensis FS213P, B. thuringiensis FB833T, B. weihenstephanensis FB25M, R frigoritolerans FB37BR, and Pseudomonas fluorescens FP805PU were initially assessed in mixtures of three, four or five bacteria in liquid, powder and isotonic solution (0.01 M MgSO4) formulations. The concentrations 10(6), 10(8) and 10(9) colony-forming units per mL were tested in a second study using one of the consortia. Results showed that the three initial consortia in first assay had similar effects on parasite control, with significantly lower reproductive indices observed after 6 months compared to the control. Damages caused by X. index were also lower for all the treatments, with no differences observed among the formulations. In contrast, the effects of the consortia against damages caused by M. ethiopica were more variable and did not correspond to the decrease of the juvenile densities in soil. The second assay confirmed previous results also showing that nematode control did not increase with the increasing concentrations evaluated.