An ecofriendly approach for management of storage rot disease of garlic caused by Aspergillus niger

Black mould of garlic, caused by Aspergillus niger, is a major post-harvest disease that leads to significant storage losses. The present study aimed to evaluate the efficacy of selected biocontrol agents and plant-based biopesticides against A. niger under in vitro and storage conditions. Four isolates belonging to three Trichoderma species and six biopesticides prepared from aqueous plant extracts and cow urine extracts were tested. Results revealed a significant inhibitory effect (p ≤ 0.05) of the tested treatments on the mycelial growth of A. niger. Among the biocontrol agents, Trichoderma koningii recorded the highest mycelial growth inhibition (69.99%). Among aqueous biopesticides, 50 per cent Ocimum sanctum extract showed the maximum inhibition of 33.34 per cent. Biopesticide prepared from Melia azedarach in cow urine (20–50%) and cow urine alone at 30–50 per cent resulted in complete inhibition of mycelial growth of fungal pathogen. In storage studies, pre-inoculation dipping of garlic bulbs in T. koningii produced the lowest disease incidence (6.20%) and disease index (5.34%). Pre-inoculation treatment with aqueous biopesticides of M. azedarach and O. sanctum completely checked the disease for two consecutive years whereas post-inoculation treatment significantly reduced the disease index. Post-inoculation treatment with cow urine alone recorded higher disease incidence (33.53%) and disease index (25.00%). Post-inoculation treatment with T. koningii resulted in comparatively lower disease incidence (28.55%) and disease index (15.83%) than the untreated control (100%). Compatibility studies indicated that the biocontrol agents and aqueous biopesticides were fully compatible with 1.9 to 3.09 per cent mycelial inhibition of biocontrol agents in aqueous biopesticides and reduced the disease when applied in combination. These findings highlight the potential of Trichoderma koningii and selected biopesticides as eco-friendly alternatives for managing black mould disease of garlic.