Roving Survey and in vitro Identification of the Fungus Alternaria porri Causing Purple Blotch of Onion in Different Growing Areas of Northern Karnataka

Roving survey on the incidence of purple blotch of onion was conducted in major onion growing regions of northern Karnataka during 2012–13 and it revealed that the disease incidence ranged from three to forty six per cent. The highest per cent disease index of Alternaria porri (46%) was noticed in fields of Sangreshkopp village in Belgaum district whereas the least per cent disease index (3%) was recorded at Hulkund village in Belgaum district. It was concluded that disease was more prevalent in Belgaum district than other districts surveyed due to more humid climate and congenial environmental conditions.