In-vitro Evaluation of Botanicals and Microbial Bioagents against Fusarium oxysporum f. sp. ricini and Rotylenchulus reniformis in Castor

Abstract

This study evaluated the in vitro efficacy of selected botanicals and microbial bioagents against Fusarium oxysporum f. sp. ricini and Rotylenchulus reniformis affecting castor under controlled laboratory conditions. Five botanicals (Piper betle, Costus igneus, Tinospora cordifolia, Tagetes erecta, and Eucalyptus camaldulensis) were tested at concentrations of 5, 10, and 15% against F. oxysporum using the poisoned food technique and against R. reniformis using an in vitro nematicidal bioassay. Five bioagents (Trichoderma harzianum, Pseudomonas fluorescens, Bacillus subtilis, B. spizizenii, and B. aryabhattai) were assessed for in vitro antifungal and nematicidal activity. Fungal growth inhibition and nematode mortality were recorded and statistically analysed. The antifungal and nematicidal activities of all botanicals increased with concentration. Eucalyptus camaldulensis was the most effective botanical, producing 75.00% inhibition of F. oxysporum mycelial growth and 75.6% mortality of R. reniformis at 15%, followed by Tinospora cordifolia. Among the bioagents, Trichoderma harzianum was the most effective, producing 75.93% inhibition of fungal growth and 72.3% nematode mortality. The bacterial bioagents also showed inhibitory activity, and all treatments performed significantly better than the untreated control. The findings indicate that E. camaldulensis and T. harzianum warrant further evaluation as environmentally compatible components of integrated management strategies for castor wilt and reniform nematode.