Comparative in vitro Evaluation of Botanical Extracts and Chemical Fungicides against Alternaria brassicae: Concentration-dependent Efficacy Assessment for Sustainable Disease Management
Yaragorla Hanumantha Rao *
Department of Plant Pathology, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur–208002, Uttar Pradesh, India.
Mukesh Srivastava
Department of Plant Pathology, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur–208002, Uttar Pradesh, India.
Siddharth Singh
Department of Plant Pathology, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur–208002, Uttar Pradesh, India.
*Author to whom correspondence should be addressed.
Abstract
Alternaria brassicae causes devastating blight in Brassica crops, leading to yield losses of up to 71% across major growing regions. Traditional chemical fungicide management raises concerns about environmental persistence, resistance development, and residue accumulation. Botanical extracts offer sustainable alternatives through bioactive antifungal compounds. This study evaluated and compared the in vitro antifungal efficacy of botanical extracts and chemical fungicides against A. brassicae through concentration-dependent assessment to determine effective concentrations, characterise inhibition patterns, and identify sustainable alternatives for disease management in mustard cultivation systems. It was hypothesised that botanical extracts would demonstrate significant, concentration-dependent antifungal activity against A. brassicae, though chemical fungicides would achieve superior pathogen suppression. These findings confirm the study hypothesis. A key limitation of this study is that all experiments were conducted under controlled in vitro conditions; field validation is required before these findings can be applied to commercial disease management. Five botanical extracts (garlic, ginger, turmeric, tulsi, lantana) at 2.5%, 5%, and 10% concentrations, and five fungicides (Carbendazim+Mancozeb, Difenoconazole, Fluxapyroxad, Penflufen, Trifloxystrobin) at 0.025%, 0.05%, and 0.1% concentrations were evaluated using the poisoned food technique on PDA medium. Radial growth inhibition was calculated using Vincent’s formula, with appropriate statistical analysis. Botanical extracts showed concentration-dependent inhibition, with garlic achieving the highest efficacy (66.44% at 10%), followed by turmeric (66.00%), tulsi (64.00%), ginger (63.44%), and lantana (60.78%). Fungicides demonstrated superior inhibition, with four achieving complete suppression (100%) at 0.1%: Carbendazim + Mancozeb (98.13% at 0.025%), Trifloxystrobin (97.18%), Difenoconazole (96.83%), and Fluxapyroxad (96.56%). Penflufen showed incomplete inhibition (97.78% at 0.1%). All treatments exhibited significant dose-dependent responses. Chemical fungicides provide superior pathogen suppression, but botanical extracts, particularly garlic and turmeric, offer promising, sustainable alternatives with substantial antifungal activity. Concentration-dependent efficacy patterns support optimized dosing strategies. Integrating botanical extracts with reduced fungicide applications represents a viable, eco-friendly approach to sustainable management of Alternaria blight in mustard production systems.
Keywords: Alternaria brassicae, botanical extracts, fungicides, concentration-dependent inhibition, sustainable disease management, antifungal efficacy