A laboratory trial was conducted at 20 ºC to investigate the effect of pH range on the growth and sclerotial formation of Sclerotium cepivorum, which causes white rot of Allium species. The obtained results indicated that pH 6 followed by pH 7 were the optimal pH degrees for growing the pathogen on PDA medium with production a large number of sclerotial populations. The lowest radial growth of S. cepivorum was observed at pH 8 and pH 4. No significant differences between diameters of each sclerotia was recorded within the tested pH range. 100 Sclerotia were exposed in the soil to one of three concentrations (5, 10 and 15 %) of composted onion, garlic and cabbage wastes under greenhouse conditions. Germination of the exposed sclerotia was determined on PDA medium in comparison with those unexposed. Failure of germination of the exposed sclerotia on PDA medium indicates damaged them within the soil in absence of the host. Due to use 15 % concentration of each compost type, higher efficiency at the first 15 exposed days was obtained. After 30 exposed days, suppressive effects of all applied concentrations of each compost type against viability of the treated sclerotia were paralleled increased in comparison with almost effect showed in control. Destroyed percentages of the exposed sclerotia were approximately pointed after 45 exposed days to the investigated waste types.  Whenever, maximal mean values of the destroyed sclerotia were done and reached 75.70, 74.26 and 72.26 % due to use of the composted garlic, onion and cabbage wastes, respectively, in comparison with 8.30 % for control in absence of the host.            Accordingly, great amounts of NH₄, NO₃, P, K and SO₄ were accumulated within the treated soils in comparison with the free soils from treatments. However, potential use of the composted wastes could be attributed to trick and destruction of the vast majority of sclerotia in the field, consequently reduces the risk of the pathogen spread to neighboring fields.