Testing the efficacy of biocontrol agents against Alternaria porri under in vitro conditions

Abstract

The Present investigation was carried out during 2015-16 in the Laboratory of the Department of Plant Pathology J. N. K. V. V. Jabalpur at Completely Randomized Design (CRD). The experiment on effect of biocontrol agent against Alternaria porri causing purple blotch of onion five biocontrol agents. Alternaria sp. is a major leaf spot and blight causing pathogen on various plant species including onion purple blotch caused by Alternaria porri. The pathogen identified as Alternaria porri attacked all above ground plant parts. Initially small, whitish sunken lesions appear on the succulent leaves. Spots are elliptical to irregular in shape, which enlarge rapidly with the advancement of the disease and coalesce to form larger dead patches resulting in the blight. Alternaria porri was found pathogenic to the onion. The pathogenicity of the fungus was established by artificial inoculation of onion leaves with the conidial suspension of the pathogen. Among the Four bioagent tested, Trichoderma viride followed by Trichoderma harzianum was most effective against A. porri under in vitro condition.