Effect of Neem (Azadirachta indica) and Castor (Ricinus communis) Leaf Extracts on Root-knot Nematodes of the Genus Meloidogyne in Tomato (Solanum lycopersicum) Culture

Abstract

Aims: During production, root-knot nematodes of the Meloidogyne genus, probably the most harmful, attack tomatoes. Given the harmful effect of certain nematicides used to control this nematode, the use of plant extracts could be an alternative for sustainable tomato production. The aim of this study was to evaluate the efficacy of neem and castor leaf extracts on root-knot nematodes in the field. Place and Study Duration: Côte d’Ivoire, from April to August 2023. Methodology: A plot previously infested with root-knot nematodes set up using a randomized complete block design. Neem and castor extracts are applied at a dose 100 g per tomato plant and furasol at 5 g, planted once a month until harvest. The density of root-knot nematodes was estimated in the soil each month before extract application and in tomato roots at harvest. Parameters such as severity and prevalence of galls, nematode density in soil and roots, plant height and fruit yield were measured during the study. Results: The prevalence and severity of root galls on tomato plants were statistically identical on plants treated with furasol and castor (P>0,05). The results showed that neem and castor extracts had similar effects to furasol on tomato plants regarding plant height (from 72,40 ± 18,38 to 78,40 ± 11,27) and fruit yield (from 4,20 ± 0,63 to 4,80 ± 0,42). These plant extracts induced a low rate of multiplication of these nematodes in the same way as furasol, and reduced the number of nematodes in the soil and roots of treated tomato plants. Conclusion: The results obtained in this study are encouraging, and the long-term use of these plant extracts could be a sustainable control method against root-knot nematodes.