Field evaluation of fungicides against Alternaria porri (Ellis) Cif., causing purple blotch of onion (Allium cepaL.)

Field evaluation of several fungicides including new molecules was undertaken for the management of purple blotch disease of onion caused by Alternaria porri(Ellis) Cif. The experiments were conducted during kharif of 2012 and 2013 using susceptible variety Arka Nikethan. Cymoxanil 8% + Mancozeb 64% WP @ 2500 ppm and Mancozeb 70% WP @ 2500 ppm were effective in reducing the disease severity by 54.86 and 52.88% over untreated control. However, Mancozeb 70% WP and Cymoxanil 8% + Mancozeb 64% WP recorded the maximum yield of 39.71 and 37.06 t/ha and obtained benefit cost ratio of 33.85 and 20.67. Thus these two fungicides can be recommended for the effective and economical management of the disease.