s 



CIRCULAR 3 7 3, U. S. DEPARTMENT OF AGRICULTURE 



Treated and untreated blueberries were held in an incubator at 

 86° F. for a period of 6 days, after which representative samples of 

 berries were compared. In the case of three varieties, the treated 

 berries were found to be slightly less firm than the untreated, as 

 shown in figure 6. 



ABSORPTION OF CARBON DISULPHIDE BY FRUIT 



Samples of blackberries were tested immediately after they had 

 been taken from the fumigation room. The proportion of carbon 

 disulphide that had been absorbed was determined by the method 

 used by Radcliffe (6). In no case did it exceed 2 milligrams to 1 

 kilogram of fruit (2 parts per million), and in all probability this 

 quantity would be practically all dissipated before the fruit reached 

 the ultimate consumer. Judging from taste, no more carbon disul- 

 phide is likely to be absorbed by the other fruits than by blackber- 

 ries. The fruits treated as recommended for the destruction of the 



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 VARIETY OF 



TREATED- — 

 UNTREATED- 



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RUBEL 

 BLUEBERRY 



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Figueb 6. — Proportions of blueberries that were firm after treatment with 10 pounds 

 of carbon disulphide per 1,000 cubic feet for 2 hours at 80° F. and subsequent 

 storage for 6 days at 86°, cmpared with the proportions of untreated berries that 

 were firm. 



beetles were apparently normal in appearance, flavor, and keeping 

 qualities when compared with untreated fruit. 



PREVIOUS EXPERIMENTS WITH ETHYLENE OXIDE 



Since the development of a method for fumigating fresh fruit 

 with carbon disulphide (5) to destroy the adult Japanese beetle, ex- 

 periments have been under way to develop a f umigant for this pur- 

 pose which would be equally effective as an insecticide and as nonin- 

 jurious to the fruit, but which in addition would be less inflammable 

 and explosive than carbon disulphide. The preliminary experiments 

 with different compounds indicated that ethylene oxide, a chemical 

 whose insecticidal properties were discovered by Cotton and Koark 

 {2) , might be substituted for carbon disulphide for this purpose. 



Cotton and Koark showed that a dosage of 1 pound of ethylene 

 oxide per 1,000 cubic feet of space for 20 hours proved to be 100 

 percent lethal to specimens of the webbing clothes moth, Tineola 

 bhelliella Hum.; the black carpet beetle, Attmgenus piceus Oliv. ; 



