Effects of sulphur and gypsum as soil treatment as well as clorox with water irrigation were tested to manage white rot of onion caused by Sclerotium cepivorum Berk. for two successive seasons (2012-2013 and 2013-2014) in greenhouse and open field in soil naturally infested with S. cepivorum at Mallawy Agric. Res. Sta., Menia Governorate. The recommended fungicide Folicure 25% EC (tebuconazole 25%) was used for comparison. In greenhouse, 1.2, 1.4 and 1.9 g/pot (25-cm-diam.) for sulphur and gypsum or 1.2, 1.4 and 1.9 ml/pot for clorox were used. While, under field conditions 100, 120 and 160 kg/fed for sulphur and gypsum or 100, 120 and 160 L/fed for clorox were tested. Under greenhouse conditions, all treatments reduced percentages of infection compared with non-treated plants. The reduction ranged between 4.2%
with 1.2 g sulphur/pot. at soil preparation time and 66.7% with clorox treatments added to water irrigation four times at the rate of 1.4 or 1.9 ml/pot, while Folicure treatment gave 75% efficacy. In field experiments, clorox application four times with water irrigation at the rate of 160 L/fed led to 64.7% disease reduction and increased bulbs yield by 248.4%
compared with 80.7% disease reduction and 119.4% increase in bulbs yield with Folicure fungicide treatment. Values for the efficiency of gypsum, sulfur and clorox in controlling the disease were somewhat similar to that found with Folicure fungicide.