Evaluation of Botanicals Aqueous Extract for Root Knot Nematode Management Under Protected Cultivation in the Mid‐Indian Himalayan Region

ABSTRACT Root‐knot nematodes ( Meloidogyne incognita ) are among the most destructive plant‐parasitic nematodes, causing major yield losses in horticultural crops. Environmentally benign alternatives to chemical nematicides are urgently needed. In this study, we evaluated the nematicidal potential of aqueous extracts from botanicals ( Pinus , Thuja , Artemisia , and Agave ) through a combination of in vitro assays, pot culture studies under protected cultivation, field validation in polyhouse trials and comparative GC–MS profiling. In vitro assays revealed pronounced variation in juvenile mortality, with Thuja and Pinus extracts consistently outperforming other botanicals across dilutions (≥ 58% mortality undiluted). Pot culture experiments confirmed these findings, showing significant suppression of galling and nematode multiplication, alongside enhanced plant growth, in Thuja and Pinus treatments—second only to carbofuran. Field validation under polyhouse conditions further demonstrated that Thuja and Artemisia significantly reduced gall density, female and egg mass counts and soil nematode populations, while simultaneously improving yield (3.9–3.97 kg/plot vs. 2.66 kg in untreated control). GC–MS profiling was performed on hexane extracts solely for phytochemical characterisation provided indicative phytochemical insights, revealing that Pinus and Thuja extracts were rich in bioactive terpenoids (cedrol, α‐pinene, 3‐carene, humulene) and sterols (γ‐sitosterol, phytol) known to disrupt nematode cuticle integrity and interfere with metabolic processes. In contrast, Agave and Artemisia extracts contained long‐chain hydrocarbons and sterols associated with moderate bioactivity. Collectively, these findings establish Thuja and Pinus as potent botanical candidates for eco‐friendly nematode management. Their dual action—direct nematotoxicity and plant growth promotion—along with chemical signatures identified via GC–MS, suggests their potential integration into sustainable, environmentally safe nematode control strategies.