62 BULLETIN 1406, U. S. DEPARTMENT OF AGRICULTURE 



outdoor air for cooling and in cold storage where cooling is by 

 mechanical means. 



The difference in results between the two methods is due almost 

 entirely to the variations in temperature prevailing in the two types 

 of storage. 



Actual temperature records obtained in many types of air-cooled 

 storage rooms in various sections of the United States show that 

 mean temperatures in common-storage rooms during the cooling fall 

 months rarely average below the mean outdoor temperature for the 

 same period. 



Mean November temperatures for the United States are shown on 

 an isotherm map. October temperatures will average about 10 to 12 

 degrees above and those for December about 10 degrees below those 

 given for November. 



It is easily possible to determine whether or not any air-cooled 

 apple-storage house is performing satisfactorily considering the 

 prevailing outdoor temperature. Mean temperatures inside should 

 equal those outdoors. 



Late-ripening varieties in any district are usually suitable for 

 common-storage holding. Varieties fairly hard at picking time and 

 softening slowly at temperatures around 40° F. will prove most sat- 

 isfactory. Varieties giving good results in Michigan, New York, or 

 New England may be entirely unsuited for common storage in the 

 southern or Pacific-coast apple sections. 



Apples soften much faster in common storage or if picked and 

 held in the orchard than while remaining on the trees. For best 

 results in common storage, the picking of most varieties should be 

 delayed as long as the fruit is holding on the tree fairly well or until 

 there is danger of freezing. Exception should be made of the Jona- 

 than when grown under long growing-season conditions. Late pick- 

 ing of good common-storage varieties results in a firmer and higher 

 quality of fruit in storage. 



Seasons when the fruit ripens early will prove very much less 

 satisfactory for holding apples in common storage than will normal 

 seasons, and seasons when apples are late ripening will prove par- 

 ticularly satisfactory for common-storage holding. 



Fruit intended for common storage does not soften faster standing 

 in a shady spot protected from rain than in the ordinary common 

 storage. Consequently, the fruit should stand outside the storage 

 until well cooled, if a sheltered place is available. 



Careful attention to the ventilation of the storage rooms is essen- 

 tial to the maintenance of low temperatures. A difference of even 

 2 to 4 degrees in temperatures obtained will markedly influence the 

 way the fruit holds in storage. 



Fruit intended for cold storage should be well ripened on the tree, 

 which results not only in better flavored fruit with better color but 

 also in fruit much more resistant to storage scald. 



Following picking, the fruit should be removed to the cold- 

 storage rooms as soon as possible. If the weather is warm every 

 day's delay in cooling the fruit will reduce the possible storage life 

 8 to 10 days. Even with relatively cool weather each day's delay 

 will result in a four or five day reduction in possible storage life. 



