Viability of sclerotia of Sclerotium rolfsii at different depths and durations in soil

Sclerotium rolfsii Sacc, a soil-borne pathogen causing root rot, stem rot, wilt and foot rot diseases in most of agricultural and horticultural crops. When the fungus completes its life cycle, sclerotia are formed on the plant parts including stems and roots of sunflower which is main source of disease development in next crops. Sclerotia of S.rolfsii survived in field soil depending on soil type, soil microorganisms and environmental conditions of particular geographical area,. Keeping this in view, experiment on viability of sclerotia of Sclerotium rolfsii at different depths and time durations in soil was conducted under screen house and field conditions at research farm of CCS, Haryana Agricultural University, Hisar. Sclerotia of Sclerotium rolfsii obtained from infected stems and  roots of sunflower plants were wrapped in synthetic nets and buried at different depths and durations. Results showed that viability of sclerotia declined gradually in screen house and sharply under natural field conditions with the increase in soil depth and time duration of burial. None of the sclerotia germinated, when placed at 15 cm depth in soil after eight month of burial as compared to 55.75 per cent germination at same depth after one month of burial under screen house conditions. None of the sclerotia germinated, when placed from 0-15 cm soil depth after nine month of burial under field conditions.