Screening of onion species against white rot disease caused by Sclerotium rolfsii Sacc. in Manipur

Abstract

White rot of onion caused by Sclerotium rolfsii has devastated onion cultivations at various small scale onion growing locations in Manipur. The maximum white rot disease incidence was observed during the month of April in all the onion species and the minimum disease incidence was observed during February month. The disease symptoms were not apparent during the first three months after planting. The symptoms of white rot became evident during second week of February with yellowing of leaves starting from tips and gradually progressing downwards. The disease became most obvious during last week of March to first week of April when the basal part of onion stem starts rotting and drooping and the plant wilts and collapse. The bulbs of infected plants are decayed and accompanied by the signs of the pathogen including white mycelium and sclerotia.