46 



CIRCULAR 369. U. S. DEPT. OF AGRICULTURE 



DRIED FRUIT 



Dried fruit is very susceptible to insect attack and must be pro- 

 tected from infestation at all times. Growers and packers usually 

 find it necessary to fumigate dried fruit before it is stored, and for 

 this purpose should equip themselves with fumigation chambers or 

 fumigable storage bins (fig. 3). The fumigation of dried fruits un- 

 der rubberized tarpaulins is reasonably effective. The fruit can be 

 fumigated and then placed in an insect-tight storage section, or it 

 can be placed directly in storage bins that are so constructed that 

 they can be fumigated from time to time as needed. Any type of 

 construction that is gaslight is suitable for storage bins. 



Figure 38 



-storage vault in which rugs are protected against fabric pests by vapors 

 of paradichlorobenzene or flake naphthalene. 



On ranches (figs. 28 and 29), where the fire hazard can be guarded 

 against, carbon disulphide can be used. It is both cheap and effec- 

 tive. A dosage of 20 pounds per 1,000 cubic feet of space and an 

 exposure of 24 hours at a temperature of 70° F. or higher will give 

 satisfactory results. 



In packing houses or storage sections where fumigation chambers 

 or fumigable storage bins are not isolated, a fumigant that does not 

 have the fire hazard of carbon disulphide is desirable. In such cir- 

 cumstances any of the following materials can be used at the dosages 

 indicated per 1,000 cubic feet: Ethylene oxide, 2 pounds; ethylene 

 oxide-carbon dioxide mixture, 20 pounds; metlryl bromide-carbon 

 dioxide mixture, 20 pounds ; methyl formate-carbon dioxide mixtures, 

 30 pounds; chloropicrin, 1 pound; ethylene dichloride-carbon tetra- 

 chloride mixture, 20 pounds ; or liquid hydrocyanic acid or its equiv- 

 alent, 20 ounces. Hydrocyanic acid gas is absorbed in considerable 

 quantities by dried fruit, but it is ordinarily quickly given off after 

 the fruit is aerated. 



TREATING THE FINISHED PRODUCT 



It is sometimes desirable to fumigate the finished package before 

 it is shipped. For this purpose a fumigation room or a vacuum tank 



