Management of Onion Leaf Blight by Alternaria alternata (FR.) Keissler by Botanicals and Bio-control Agents

Field experiment was carried out to assess the efficacy of plant oils, plant extracts and antagonistic microorganisms against leaf blight disease of onion caused by Alternaria alternata. Two sprays of neem oil (3%) given on onion plants at the first appearance of the disease and the second on 15 days later recorded significantly the lowest percent disease index (22.22%) and besides increasing the yield. In plant extracts Acorus calamus rhizome extract 10% was significantly reduced the disease incidence (34.78%) followed by Mentha arvensis leaf extract.