Cultural practices in relation to purple blotch disease of onion

Abstract

Transplanting onion on 1 December gave the highest percentage of purple blotch infection. Percentage and severity decreased significantly by decreasing plant density. ‘Behairy’ onion was more resistant than ‘Giza 6’. Nitrogen fertilization at twice the normal level increased the percentage and severity of infection, while a double dose of calcium superphosphate reduced infection. On the other hand, percentage of infection decreased by adding potassium chloride at twice the normal level, while severity of infection increased significantly. Application of fungicides reduced percentage and severity of infection. Bavistin gave the best control.