Experiments on the control of white rot (Sclerotium cepivorum Berk.) in onions

Experiments‐made during 1943 and 1944 on the use of mercurous chloride (calomel) for the control of Sclerotium cepivorum in spring‐sown onions are described. The application of 4% calomel dust to the seed drill at sowing time gave better results than seed treatment. 1 lb. of dust per 25 yd. of seed drill gave good disease control in bulb onions, and 1 lb./so yd. may suffice for salad onions. The relation between disease control and the effective mercury content of the treated soil is discussed.