Assessment of bio-control agents and botanical formulations for the suppression of Lasiodiplodia theobromae induced root rot in Mulberry (Morus alba L.)

Abstract

The present investigation evaluated the bio-efficacy of various fungal and bacterial bio-control agents, along with selected botanical extracts, against Lasiodiplodia theobromae, the causal pathogen of root rot in mulberry (Morus alba L.). Ten bio-agents were screened using the dual culture technique and eleven botanical extracts were tested under in vitro conditions employing the poisoned food method. Among the bio-agents, Trichoderma harzianum (Th-2) recorded the highest mycelial inhibition (57.59%), followed by T. viride (Tv-1) with 46.76% inhibition. Trichoderma bravicompactum strains (Tb-1 and Tb-2) also showed moderate antagonistic activity, whereas Bacillus subtilis exhibited the least inhibition (24.81%). Among the botanicals, garlic extract proved most effective, achieving complete (100%) inhibition at 15% and 20% concentrations and substantial suppression even at lower concentrations. Agave extract also demonstrated notable antifungal activity, while onion extract showed moderate inhibition. Other botanicals, including neem, gliricidia, subabul and lantana, were comparatively less effective. The results confirm the strong antagonistic potential of Trichoderma spp. and garlic extract against L. theobromae, highlighting their prospective use as eco-friendly alternatives for managing mulberry root rot disease.