In vitro evaluation of fungicides and bioagents against collar rot of elephant foot yam caused by Sclerotium rolfsii Sacc.

Abstract

The pathogen was isolated from infected stem of Elephant foot yam on Potato Dextrose Agar in laboratory. The dark brownish lesions developed on stem and shriveling of the stem extended above collar for 2-5 centimeters. Thick mycelial mat and whitish pre mature sclerotia developed around collar region which later on converted into brown. Finally the seedling collapsed after 19th days of inoculation in field. In an in vitro experiment, among the fungicides tested in vitro, propiconazole and metalxyl + mancozeb at 0.1 per cent, mancozeb 0.25 per cent totally inhibited mycelial growth and sclerotia formation of pathogen. Among the bioagents tesed, T. harzianum resulted with significantly highest mycelial growth inhibition (68.88 %) and least number of sclerotia (6), followed by T. viride (56.66 % and 9.25) and T. koningii (43 % and 11.0).