MAKKET DISEASES OF APPLES, PEAES, QUINCES 25 



through high altitudes and extremely low temperatures, often for 

 several days. However, apples that show evidence of freezing 

 injury upon reaching the market have not necessarily been frozen 

 in transit. Freezing in the orchard sometimes occurs both in the 

 East and in the West. There are also occasional opportunities for 

 freezing injury during the handling or storing of fruit previous to 

 its actual shipment. 



At present there are no known symptoms of freezing injury that 

 clearly indicate, for a single apple, the time when or the conditions 

 under which the damage occurred. On both of these points the most 

 reliable evidence is furnished by the distribution of the injury in the 

 car, though even by that no more is indicated than that freezing 

 occurred either prior to loading or during the transit period. 

 Transit freezing occurs first at the doorway of the car, along the 

 floor and side walls, and near the bunkers ; upon prolonged exposure 

 to low temperature it may extend deeper into the load. If freezing 

 is not present in the outer parts of the load, no transit freezing 

 should appear elsewhere in the car. If the injury is uniformly scat- 

 tered through the package and through all parts of the load, in all 

 probability the freezing took place before the product was loaded. 



The amount of injury that an apple may suffer from freezing 

 depends on the length of the exposure to low temperature, on how 

 low the temperature goes, and on other conditions affecting the fruit 

 when freezing occurs. Usually these conditions as well as the rate of 

 thawing are unknown when the apples are inspected, and conclu- 

 sions must be drawn from the appearance of the fruit at the time 

 it is examined. 



It should be remembered that a sound, healthy apple is a living- 

 organism. When it freezes, ice crystals form within the tissues (not 

 in the cells but between them), and the tissues are injured or dis- 

 organized by the action of physical factors that interfere with the 

 normal life processes of the fruit. Other kinds of disorganization, 

 at first sight somewhat similar to freezing injury, are produced by 

 exposure to high temperature, by treatment with ether and other 

 poisonous substances, by diseases due to blue-mold or other organisms, 

 and by the natural breakdown due to old age. The extent to which 

 the life processes are affected depends largely upon the degree to 

 which the disturbing factor is applied. If that factor is low tem- 

 perature, the extent of the injury to the fruit will depend on factors 

 already mentioned and may range from slight damage to complete 

 disorganization in which every cell is browned and the apple is 

 " frozen to death." 



FREEZING POINT OF APPLES 



Accurate determinations on several hundred specimens of the more, 

 important commercial varieties (Winesap, Stayman Winesap, Yellow 

 Newtown, Ben Davis, Baldwin, Rome Beauty, Wagener, Jonathan, 

 Mcintosh, Tompkins King, Grimes Golden) show that the freezing 

 point of these varieties ranges from 27.32° to 29.40° F. ; the average 

 is 28.43°. For any individual specimen, unless the temperature of 

 the air surrounding it is suddenly lowered much below 27° to 29°, the 

 temperature of the inside tissues often drops temporarily a degree 

 or more below the true freezing point without any formation of ice. 



