BULLETIN OF THE 



No. 186 



Contribution from the Bureau of Entomology, L. O. Howard, Chief, and the 

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



February 27, 1 91 5. 



A METHOD OF FUMIGATING SEED.^ 



ByE. 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 ia seeds 

 imported into this country, ^yithout 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 laryal and pupal stages and a portion of the 

 adult stage inclosed \\dthin the seed and on this account might easily 

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

 frequently receiyed from localities where injurious insects are not well 

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

 native habitats occasionally become destructive pests when estab- 

 lished in this country. 



ITie ordinary methods of destroying insects in stored seeds, such 

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

 bisulj)hid, and hydrocyanic acid in the presence of air, have been 

 tiled 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 ])laced and fill the chambei- with 

 some gaseous insecticide, such as carbon bisulphid or hydrocyanic 

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

 forced iutr; the crevices of the seeds and into the iiisect galleries than 

 would be ])ossihle if the e/itrance of the gas \vere de])endent u})OJi 

 di/rusion under normal atiiiospheiic pressure. This in(>thod was suc- 

 <-essfully used with a ]unn(>er of did'eicnt kinds of s(«e(ls ajid insects, 

 and a convenient chamher, (h'sciibed latei-, was (l(>yise<l for fumigation 

 under reduc(!d pressure. 



'ThlH uork was (rsirrlcl on in cwixTiilioii Ix-twwn the I-'cdcruI llorllcultiirul Hoard uikI the Odlue of 

 I'lant I'hy.Hlolo({l<«l and I-Vrm.-ntation Inv.-siiKOtlons, Uiireau of I'imit Industry, U. S. L>ei)iirtinont of 

 AfpicTiltiirc. 



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