Sensitivities of nematode-inoculated tomato plants to Nemarioc-AL phytonematicide from fresh Cucumis myriocarpus fruit

Abstract

Costs related to temperature-dependent drying and grinding equipment of Cucumis myriocarpus fruit for preparation of Nemarioc-AL phytonematicide could inherently restrict on-farm preparation of this product, particularly in resource-poor smallholder farming systems. The objective of this study was to determine the overall sensitivities of tomato (Solanum lycopersicon L.) plants and nematodes to Nemarioc-AL phytonematicide produced using fermented crude extracts of C. myriocarpus fresh fruit thereby establishing the feasibility of producing this product on-farm. Uniform five-week-old tomato cv. ‘Floradade’ seedlings were transplanted into plastic pots containing a growing mixture, with treatments 0, 2, 4, 8, 16, 32 and 64% Nemarioc-AL phytonematicide applied weekly on plants inoculated with 3000 Meloidogyne incognita eggs and second-stage juveniles (J2). At 56 days after initiating the treatments, plant and nematode variables were subjected to analysis of variance. Nematode variables over increasing log2 2-transformed concentrations were subjected to lines of the best fit. Nematodes versus increasing concentrations of phytonematicide exhibited negative quadratic relations, with the model for eggs and J2 in roots and soil being explained by 90 and 95% relations, respectively. Plant variables were subjected to the Curve-fitting Allelochemical Response Data (CARD) computer-based model to generate biological indices. The mean concentration stimulation point (MCSP = Dm + Rh/2) was computed 2.79%, with the overall sensitivity (Σk) of four units. In conclusion, Nemarioc-AL phytonematicide from fermented fresh fruit of C. myriocarpus could be used in managing population densities of Meloidogyne species in tomato production without inducing phytotoxity.