Feb. 24. 1919 A pple-ScaCd 217 



SUMMARY 



The foregoing experiments furnish conclusive proof that apple-scald 

 is a preventable disease. The following are some of the more salient 

 facts that have been experimentally established. 



(i) Well-matured apples are much less susceptible to scald than 

 immature ones. 



(2) Apples from heavily irrigated trees scald worse than those from 

 trees receiving more moderate irrigation. 



(3) The rapidity of development of apple-scald increases with a rise 

 in temperature up to 15° or 20° C, the optimum often shifting from 20° 

 to 15° C. during the storage period. 



(4) Apple scald has not occurred at temperatures of 25° or 30° C. 



(5) It has been found possible to store apples in air saturated with 

 water vapor without the development of scald. In several different 

 experiments scald was considerably reduced by decreasing the humidity, 

 but the beneficial effects were apparently not entirely due to the decreased 

 moisture in the air. 



(6) Accumulations of carbon dioxid (i to 6 per cent) have not favored 

 the development of apple-scald, but tended to prevent it. 



(7) Apples susceptible to scald have been made immune by storing 

 for a few days in an atmosphere of pure carbon dioxid. 



(8) Increasing the percentage of oxygen in the air has not given 

 consistent beneficial effects upon apple-scald. 



(9) A constant air movement of from yi to % mile per hour has 

 always either entirely prevented apple-scald or reduced it to a negligible 

 quantity. The intensity of the air movement was apparently more 

 important than the continuity and the circulation of the air more impor- 

 tant than its renewal. 



(10) Scald has been greatly reduced by shifting apples from one 

 temperature to another. The beneficial effects are attributed to the 

 aeration of the apple tissue thus obtained. 



(11) Thorough aerations during the first eight weeks of storage have 

 been more helpful than later ones. 



(12) Apples have scalded less in air-cooled cellar storage than in 

 unventilated commercial cold storage. 



(13) Apples packed in boxes or ventilated barrels have scalded much 

 less than those in tight barrels,especially when the storage room received 

 an occasional ventilation. 



(14) Scald was greatly reduced on rather immature apples by a delay in 

 storing, if the fruit was well aerated during the delay, but was increased 

 by the delay if held under conditions that allowed Httle or no ventilation. 



(15) Ordinary apple wrappers have had no effect on apple-scald, and par- 

 affin wrappers but little; but wrappers soaked in various mixtures of olive 

 oil, cocoa butter, vaseline, or beeswax have entirely prevented apple-scald. 



(16) Apple-scald is due to volatile or gaseous substances other than 

 carbon dioxid that are produced in the metabolism of the apple. They 

 can be carried away by air currents or taken up by various absorbents. 



