BULLETIN OF THE 



!HIOFAI 



No. 186 



Contribution from the Bureau of Entomology, L. O. 



Bureau of Plant Industry, Wm. A. Taylor, C 

 February 27, 1915. 



A METHOD OF FUMIGATING SEED. 



AGlCULT:jf?| 

 CALIFORNIA 



By E. R. SASSCER, Chief Inspector, Federal Horticultural Board, and LON A. HAWKINS, 

 Plant Physiologist, Plant Physiological and Fermentation Investigations. 



INTRODUCTION. 



A perfectly reliable method of destroying insects present in seeds 

 imported into this country, without injury to the seed, is much 

 needed. The exclusion of insects by a careful selection of apparently 

 uninfested seeds at the port of export is impracticable, because many 

 injurious insects pass their larval and pupal stages and a portion of the 

 adult stage inclosed within the seed and on this account might easily 

 escape notice when the seeds were inspected. Furthermore, seeds are 

 frequently received from localities where injurious insects are not well 

 recognized, and, also, insects which are only slightly injurious in their 

 native habitats occasionally become destructive pests when estab- 

 lished in this country. 



The ordinary methods of destroying insects in stored seeds, such 

 as subjecting them to heat (with or without moisture), carbon 

 bisulphid, and hydrocyanic acid in the presence of air, have been 

 tried and found unsatisfactory for this purpose. 



It occurred to the writers to create a partial vacuum in the con- 

 tainer in which the seeds had been placed and fill the chamber with 

 some gaseous insecticide, such as carbon bisulphid or hydrocyanic 

 acid, in the belief that a much larger amount of gas might thus be 

 forced into the crevices of the seeds and into the insect galleries than 

 would be possible if the entrance of the gas were dependent upon 

 diffusion under normal atmospheric pressure. This method was suc- 

 cessfully used with a number of different kinds of seeds and insects, 

 and a convenient chamber, described later, was devised for fumigation 

 under reduced pressure. 



1 This work was carried on in cooperation between the Federal Horticultural Board and the Office of 

 Plant Physiological and Fermentation Investigations, Bureau of Plant Industry, U. S. Department of 

 Agriculture. 



75871 Bull. 18615 



