126 



TREATMENT OF SEED FOR SHIPMENT. 



Since under exceptional conditions it is often desirable and some- 

 times necessary to allow limited- shipments of seed from infested to 

 noninfested territorj^, some means of treatment has been sought by 

 which the danger of carrying live weevils with the seed will be prac- 

 tically eliminated. To discover some ejffective method of treatment 

 each of the most promising fumigants was carefully tested. Among 

 these carbon bisulphid (CSg) proved to be most effective. Treatment 

 with this, however, was successful only when the application was made 

 with apparatus specialh^ designed for this purpose. Instead of expos- 

 ing the bisulphid above or outside of a mass of seed, as has been the 

 usual practice heretofore, an apparatus was devised by which the 

 vaporization of the liquid was forced and the vapor driven into the 

 mass of seed and its diffusion accelerated by pressure from an air 

 pump. This method of forcing the vaporization and diffusion of 

 carbon bisulphid is original, and has been fully described in Farmers' 

 Bulletin No. 209, pages 9-11. By it two men can treat fully a thou- 

 sand bushels of seed in a day, with an expense, for bisulphid and labor, 

 averaging about one-half a cent per bushel. Even with the most 

 careful treatment, however, it can never be guaranteed that seed is 

 absolutely free from the possibility of carrying live weevils, since, 

 occasionally, the weevils may. be found in small, hard, tightly closed 

 bolls, such as were those shown in Plate XIX, figure 79, before the 

 weevils emerged. It is doubtful whether even a thorough treatment 

 with carbon bisulphid would destroy weevils so thoroughly protected 

 as were these. The best that can be said of seed thus treated is that it 

 is probabl}" free from living weevils. 



For methods and experiments dealing much more twlly with the 

 general subject of the relation of gins to weevil dissemination we must 

 refer to Farmers' Bulletin No. 209. 



Besides guarding against unrestricted movement b}^ shipment of 

 possibl}^ infested seed, great care must be exercised to properly clean 

 cars in which shipments have recently been made. Experiments 

 made in this work indicate that a satisfactory method of treating such 

 cars where steam connection is available is to close the doors as tightly 

 as possible and turn into the car a jet of live steam, continuing the 

 treatment for about ^ve or ten minutes. This treatment has been 

 found to kill weevils placed in the least exposed portions of the car. 

 A general outline of the experiment by which this conclusion is 

 sustained is as follows: 



For treatment a box car was selected of 34 feet, inside measure, and 

 having 60,000 pounds capacity. • Weevils, part of which were fullj^ 

 exposed and part buried under about three-fourths of an inch of seed, 

 were placed in the far corners of the car upon the floor. In one corner 



