Farmers' bulletin (United States. Dept. of Agriculture) ; no. 996

"The tobacco seedling is subject to injury in the seed bed by weeds and a number of parasitic enemies, among which is a fungus root-rot. It is of the utmost importance to secure beds free from weeds and to avoid the use of diseased or weak seedlings. Methods of sterilization have been developed to control seed-bed conditions.... This bulletin describes the necessary equipment and method of operation, with certain special features of seasonal convenience and seed-bed preparation. The method is applicable for working on either small or large seed-bed areas and can be used in all tobacco-growing districts. With necessary modifications in the apparatus which will readily suggest themselves to the truck grower, the method can be used very successfully to control soil conditions in the greenhouse, in cold-frames, or in the field." -- p.