III. THE HANDLING OF APPLES FOR STORAGE 



By J. R. Magness, Physiologist, H. C. Diehl, Assistant Physiologist, and M. H. 

 Hallee, Junior Pomologist, Office of Horticulture, Bureau of Plant Industry 



There are two general methods of storing the commercial apple 

 crop in the United States. The first of these is the holding of the 

 fruit in common, or air-cooled, storage, where the temperatures main- 

 tained are obtained primarily through ventilation with cool outdoor 

 air. The second method is to put the fruit in cold storage, where 

 artificial cooling, usually by refrigerating machines, makes it pos- 

 sible to hold the temperatures at approximately the point most satis- 

 factory for preserving the product. It is impossible to get exact 

 information on the quantity of the commercial apple crop of the 

 United States handled through air-cooled, or common, storage, but 

 apparently it is equal to considerably more than half of the total 

 commercial apple crop of the country. Available statistics relative 

 to the holding of apples in cold storage indicate that somewhat less 

 than half of the commercial apple crop of the United States is han- 

 dled in this way, the remainder being either marketed directly or 

 held for varying lengths of time in air-cooled storages. 



In Part II the discussion dealt primarily with the influence of 

 different temperatures on the ripening of apples following their 

 removal from the tree. It was pointed out that temperature is ap- 

 parently almost the sole determining factor in the rate of ripening 

 of any variety following picking. The difference in results obtained 

 in holding apples in an air-cooled storage as compared with holding 

 them in cold storage will largely depend upon the difference in the 

 temperatures maintained in the two types of storage. 



TEMPERATURES PREVAILING IN AIR-COOLED STORAGES 



During the past 10 years the Lmitecl States Department of Agri- 

 culture has obtained thermographic records of the temperatures pre- 

 vailing in common, or air-cooled, apple-storage houses in many sec- 

 tions of the United States, including basement, hillside, and above- 

 ground storages of various types. From these records it is possible 

 to make some general statements regarding the temperatures which 

 may be expected in air-cooled storage houses. 



It is rarely found that the mean temperature existing in an apple 

 storage house or basement which depends upon outside air tempera- 

 tures for cooling will, over a period as long as 10 days, be appre- 

 ciably below the mean of the outdoor temperatures during that time. 

 By outdoor temperatures are meant shade temperatures as reported 

 by the United States Weather Bureau. In a great many cases exist- 

 ing outdoor temperatures, particularly during the fall "months, will 

 average considerably below the mean of those inside the storage. 

 Storage temperatures are usually above the mean of those prevailing 



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