Eco-friendly management of black mould rot of onion (Aspergillus niger Van Tieghem)

Abstract

Black mould rot of onion incited by Aspergillus niger is an economically important post-harvest disease of onion under storage conditions and cause extensive losses. Application of fungicides to manage the disease cause residue problems, as it is directly consumed. Therefore, the study was undertaken to manage the black mould rot disease through application of phytoextracts and salts in vitro and in vivo. Among all phytoextracts screened, custard apple, neem, ghaneri and amaranthus extracts at 10 per cent concentration completely inhibited the mycelial growth of A. niger followed by moringa (97.30 %) over control. The results of in vivo study revealed that custard apple, neem, ghaneri and amaranthus leaf extracts (10 %) found most effective in controlling the black mould rot over control on 7^th and 14^th day after inoculation in pre- and post-inoculation treatments. Among the salts screened, aluminum acetate, sodium benzoate, sodium carbonate, sodium bicarbonate and ammonium phosphate at 0.2 M concentration completely inhibited the mycelial growth of A. niger over control on 7^th day after inoculation in vitro. In pre-inoculation treatment, severity of black mould rot disease was negligible in bulbs treated with aluminum acetate (0.00 & 0.67 %) at 7^th and 14^th day after inoculation. Similar trend of results was noted in post-inoculation treatments.