OZONE IN RELATION TO STORAGE OF APPLES 



17 



because it was imperative that wound parasites such as blue mold 

 should not get started. 



The fruit was dipped into an aqueous spore suspension to which 

 was added a small amount of a commercial wetting agent as a spreader. 

 No effort was made to control the concentration of spores, but the 

 inoculum was examined microscopically to make certain that there 

 was an abundance of them. The fruit was allowed to dry and was 

 then packed in boxes and stored in equal lots in the two test rooms. 



Ozone failed to control side rot on the apples that had been inocu- 

 lated with spores of Phialophora. In some instances more infections 

 occurred on the ozonized fruit than on the nonozonized. This may 

 have been due to lenticel injuries caused by the ozone. 



A summary of the results of these tests is given in table 7. 



Table 7. — Effect of ozone on the development of decay on wounded 

 apples inoculated with spores of Phialophora malorum and subse- 

 quently stored in ozonized rooms at 31° F. for various periods 



[Final examination made after 7 days at 70° F. without ozone] 



Variety and ozone treatment 



Storage 



period 



at31°F. 



Subse- 

 quent 

 period 

 at 70° F. 



Fruit 

 inocu- 

 lated 



Fruit 

 infected 



Lesions 

 per 

 fruit 



Rome Beauty: 



3.25 p. p. m 







York Imperial: 



3.25 p. p. m 







Days 

 \ 130 



} 130 

 j 90 



Days 



7 



7 



7 



Number 

 ( 61 

 1 65 



/ 45 

 1 35 

 / 45 



1 129 



Percent 

 68. 9 



72. 3 



100.0 



94.3 



22. 2 



9. 3 



Number 

 5. 6 



7. 1 



32. 4 

 19. 2 



1.95 p. p. m 







. 9 

 . 2 



Fruit in the Regular Pack 



All the test fruit was examined near the end of each storage season 

 to determine the effect of ozone on development of decay in the regular 

 pack. With one exception there was consistently less decay in the 

 ozonized fruit than in the nonozonized, but the difference was very 

 slight. This difference could be accounted for by the small number of 

 infections that occurred after the apples were placed in the nonozo- 

 nized storage. Evidence indicates that ozone kills unprotected spores 

 in the air, but not those protected by wounded tissue or by the tissue 

 of natural infection courts such as lenticels. Smock and Watson (2Jf) 

 reported that ozone may have no effect on spore germination if the 

 spores are protected by moist surfaces of apple flesh or by other 

 organic protectants. In an interesting experiment designed to test the 

 penetrative power of ozone, Elford and Van den Ende (4) found that 

 an ozone concentration of 330 p. p. m. achieved complete surface 

 sterilization of serum agar inoculated with Staphylococcus aureus but 

 that there was no appreciable penetration of disinfecting action below 

 the surface. These findings emphasize the striking weakness of ozone 

 as a f umigant ; once an organism has become established so that any 



