Comparative Evaluation of Organic Amendments Against Meloidogyne incognita in Tomato Seedlings

Abstract

Tomato ( Solanum lycopersicum L.) is a globally important vegetable crop whose productivity is significantly constrained by root‐knot nematodes ( Meloidogyne incognita ). The results revealed that all organic amendments significantly reduced nematode population and associated disease parameters compared to the untreated control. Among the treatments, neem cake applied at 2 t ha −1 exhibited superior performance, recording the lowest nematode population in soil (80.00 and 112.22 J2/200 cc soil during 2023–2024 and 2024–2025, respectively), minimum number of egg masses and eggs per mass, and substantial population reduction (52.84%–58.93%). Neem cake also resulted in the lowest reproduction factor (0.62 and 0.42) and root‐knot index (0.78 in both years), indicating effective suppression of nematode multiplication and disease severity. Furthermore, it enhanced seed germination, achieving the highest germination percentage (93.33% and 94.67%). The suppressive effects of organic amendments may be associated with the release of biologically active compounds, including ammonia, organic acids and phenolic compounds, during decomposition, as well as with stimulation of antagonistic soil microorganisms, as reported in previous studies. Although these mechanisms were not directly assessed in the present experiment, they provide plausible explanations for the nematode suppression observed following amendment application. Carbofuran showed efficacy statistically comparable to neem cake for several measured parameters; however, given the broader pesticidal activity of carbofuran and the increasing emphasis on environmentally sustainable pest management, the consistent performance of neem cake is noteworthy. The present findings therefore suggest that neem cake is a promising organic amendment for the management of M. incognita in tomato nurseries and could contribute to reducing reliance on chemical nematicides. Its potential benefits for soil organic matter and crop establishment further support its integration into sustainable and integrated nematode management programs, although these soil‐health effects were not directly quantified in the present study.