Effect of Inoculum Levels on Disease Development and Survival Potential of Sclerotinia sclerotiorum Sclerotia

Abstract

Sclerotinia stem rot is constantly appearing from moderate to severe form in major mustard growing tracts. Most of life S. sclerotiorum passes in form of sclerotia in the soil. Present study was carried out in order to determine effect of inoculum level on disease development and survival of S. sclerotiorum. Different inoculum levels were prepared from culture of S. sclerotiorum and 10 sclerotia/ pot were buried at various depths ranging from 1 to 20 cm for 60 days. The maximum disease incidence (93.67%) was observed with 10 per cent inoculum level; however disease incidence was least (6.34%) in 1 per cent inoculum level. Disease incidence increased with increasing in inoculum levels. In case of plant mortality, maximum plant mortality (43.00%) was recorded at 10 per cent inoculum level followed by 32.67 and 29.34 per cent @ 9 and 8 per cent, respectively. No plant mortality was noticed at 1 and 2 per cent inoculum level. Maximum amount of sclerotia germination (83.33%) was observed at 1 cm soil depth followed by 75.65, 73.34, 70.34 per cent germination @ 2, 3 and 4 cm depth of soil, respectively. It was observed that sclerotial germination decreased in tune with increase in soil depth. Lowest sclerotial germination (10%) was observed in 20 cm vertical soil depth. Findings of this study can be harnessed in varietal screening and formulation of disease management modules.