Archives of Current Research International

Foot rot caused by Phytophthora capsici is a major destructive disease of black pepper, and the increasing concerns over fungicide resistance and environmental safety have intensified the search for eco-friendly botanical alternatives.The present study evaluated the antifungal potential of sixteen locally available plant extracts against Phytophthora capsici under in vitro conditions with particular emphasis on growth inhibition, biomass reduction, concentration response, and thermal stability of bioactive compounds. All tested botanicals exhibited inhibitory effects on the pathogen, with mycelial growth reduction ranging from 18.1% to 38.9%. Among them, Lantana camara recorded the highest inhibition (38.9%) followed by Acorus calamus and Chromolaena odorata (34.7%). More notably, biomass suppression was substantially higher ranging from 5.3% to 92.1%, indicating a stronger impact of the extracts on fungal proliferation. Maximum biomass inhibition was observed in Acorus calamus (92.1%), followed by neem (89.2%) and lantana (86.5%) while ginger, turmeric, Chromolaena odorata, Clerodendron infortunatum, Pongamia pinnata and Glyricidia sepium extracts also achieved more than 65% reduction. Dose-dependent inhibition was evident in most promising botanicals particularly Acorus, turmeric and neem with mycelial growth inhibition increasing up to 70.6% at higher concentrations (12.5%). Certain extracts such as ginger, Lantana, Clerodendron and Chromolaena induced visible mycelial degeneration, suggesting structural and cytotoxic effects on the pathogen. Furthermore, crude extracts were found to be more effective than thermally treated extracts, with Acorus and turmeric achieving nearly complete (≈100%) suppression of biomass production, indicating possible degradation of heat-sensitive bioactive compounds upon thermal exposure. Overall, the results highlight the superior efficacy of selected botanicals, especially Acorus calamus, neem, and turmeric as potent antifungal agents against P. capsici.  Further studies are needed to validate their effectiveness under field conditions and to isolate and characterize the active fungicidal compounds.