Management of Root-Knot Nematode-Fusarium Wilt Complex with different Bio-management methods in Tomato (Solanum lycopersicum L.) var Srijana
The root-knot nematode-Fusarium complex is a major constraint to protected tomato cultivation in Nepal, particularly on the widely grown Srijana hybrid, which lacks Mi-mediated nematode resistance. The present study was conducted to identify the most effective biocontrol agent, to identify the most effective Solanum rootstock, and to compare the overall efficacy of grafting versus biocontrol agents under polyhouse conditions. For the management of the root knot nematode-Fusarium complex, a pot experiment was set up in a completely randomized design at Pokhara, Kaski. Treatments comprised Trichoderma viride, Pseudomonas fluorescens, their half-dose combination, self-grafted Srijana, and four resistant rootstocks (S. sisymbriifolium, S. melongena, S. torvum, and VNRRs-10), together with nematode-only, Fusarium-only, complex (Nematode + Fusarium), and disease-free controls. Each plant was inoculated with approximately 2,000 nematode eggs, followed by 25 ml of 10^6 spores per ml of Fusarium seven days later to mimic the field complex. Plant growth parameters and nematode infestation data were recorded and analyzed via RStudio v. 2026.04.0. The root knot nematode-Fusarium complex caused significantly greater reductions in vegetative biomass than root knot nematode and Fusarium alone (20.32 gm vs 38.40 gm vs 51.32 gm) at 45 DAT. Single-agent biocontrol gave intermediate protection (T. viride 64.9%; P. fluorescens 47.9% nematode management efficiency), whereas combined T. viride + P. fluorescens treatment produced the highest vegetative biomass but the weakest nematode suppression (320 galls, reproduction factor: 38). Grafting onto S. torvum and S. melongena resulted in the greatest nematode suppression, achieving 97.9% and 93.6% management efficiency, respectively, while S. torvum alongside VNRRs-10 maintained the highest Fusarium suppression (92.5%). Overall resistant rootstocks consistently outperformed biological control in reducing disease severity. These findings indicate that grafting onto resistant solanum rootstocks, particularly S. torvum and S. melongena, was observed as the most effective strategy for managing the root knot nematode-Fusarium complex under protected cultivation, offering a viable chemical-free management option. Keywords: Root-Knot Nematode, Fusarium oxysporum, RKN-Fusarium-complex, Solanum torvum