Biological Control of Root-Knot Nematodes in Vegetable Crops Using Two Strains of Trichoderma spp. in Cote d’Ivoire

Abstract

Tomato cultivation (Solanum lycopersicum L.) plays an important role in Côte d'Ivoire's agricultural system and local economy, contributing to food security and producer incomes. However, despite the use of chemical inputs and organic fertilisers, yields remain below national demand. This situation is mainly linked to soil degradation, phytopathogenic diseases, and attacks by soil-dwelling pests, particularly parasitic nematodes. Among these, root-knot nematodes of the genus Meloidogyne are recognised as the most harmful, causing root deformities, reduced nutrient uptake, and significant losses in yield and fruit quality. Given the environmental and health limitations of chemical control methods, biological control appears to be a sustainable alternative. Fungi of the genus Trichoderma spp. are widely studied for their biocontrol potential, based on mechanisms of competition, antibiosis, parasitism, and induction of systemic plant resistance. The objective of this study was to evaluate the effectiveness of different strains of Trichoderma spp. in controlling root-knot nematodes (Meloidogyne spp.) in tomato crops, under preventive and curative conditions, as well as their effects on certain agronomic parameters. The experiment involved twelve treatments, each comprising eight plants, for a total of ninety-six plants. Two strains of Trichoderma spp. were applied at a concentration of 10⁷ spores/mL at a rate of 20 mL per plant. Second-stage juveniles (J2) of the nematodes were isolated from egg masses collected from infested lettuce roots. The parameters evaluated included root gall index, nematode density, and certain vegetative growth parameters. The results showed a significant reduction in root gall index and nematode densities in plants treated with Trichoderma spp. (p < 0.05) compared to inoculated controls. However, no significant effect was observed on growth parameters. These results confirm the potential of Trichoderma spp. strains as a sustainable biocontrol tool for root-knot nematodes in vegetable crops. It is recommended that further study should be developed beyond flowering, by evaluating the effect of the strains on fruiting and tomato yield, in order to measure their concrete contribution to agricultural production.