In vitro efficacy of fungicides against Alternaria porri (Ellis) Cif. causing Purple blotch of onion

In vitro testing of fungicides was carried out against Alternaria porri (Ellies) causing purple bloch of onion. The most effective fungicides were mencozeb and thiram with 83.8 and 81.3% inhibition of Alternaria porri Cif. respectively. Highest concentration (2000 ppm) of all fungicides significantly inhibited the fungal growth than lower concentrations of 500 and 1000 ppm. The treatment of mancozeb, thiram, copper hydroxide, copper oxychloride and chlorothalonil inhibited more than 50% growth even at lower concentration (500 ppm). The results indicated that the fungal growth of Alternaria porri (Ellis) Cif. could be controlled with the help of mancozeb, thiram and copper hydroxide.