Induction of resistance in onion against purple leaf blotch disease through chemicals

Onion is one of the world’s most important vegetable crop cultivated in Pakistan and plays a significant role in human diet. Numerous diseases attack on onion crop, but purple leaf blotch is the most important one, because it causes 80 to 90% of onion yield loss all over the world. In current experiment twenty-three fungicides at three concentrations (0.5, 1, and 1.5 g/L) were evaluated against Alternaria porri causing purple blotch under Randomized Complete Block Design (RCBD) on susceptible variety of onion (Pink Panther). Among all fungicides, chlorostrobin expressed prominent results causing 62.05% reduction in disease severity, followed by Nanok (61.55), Shincar (54.86), Cabrio top (53.33), Thril (50.00), Jalwa (48.11), Success (45.00), Alliette (41.61), Rally (39.83), Copper oxychloride (36.66), Score (33.05), Topas (29.88), Melodydue (13.27), Dithane M (11.66), Sulphax (6.55), Ridomil Gold (3.38) % respectively as compared to control. Similar results were observed in case of interaction b/w treatments and their concentrations. Results of current study are helpful for farmers, scientist, and researchers for timely management of purple leaf blotch disease of onion.