20 



CIRCULAR 



U. S. DEPARTMENT OF AGRICULTURE 



The time of appearance and the extent of the injury varied with the 

 variety. Golden Delicious being the most susceptible and TV inesap 

 the least susceptible of the varieties stored. The injury appeared first 

 as slightly discolored spots at the lenticels. indicating killed lenticel 

 tissue. Later these spots became sunken and dark brown. Badly 

 injured fruit was severely pitted and spotted. Most severe injury oc- 

 curred on fruit nearest the ozonizer and in the surface layers in the 

 packages. 



On January 12. the date of the first examination of Golden Delicious 

 apples, which normally have large and conspicuous lenticels. severe 

 injury was found (fig. 7. A ) . As shown in table 10. all of this variety 

 that had been stored in the ozonized atmosphere showed severe injury. 

 Several boxes of Golden Delicious fruit from another storage room 

 without ozone were then placed at various locations in the ozonized 

 room. After 10 days very slight injury was detected on the top fruit 

 near the ozonizer. The injury was conspicuous on Golden Delicious 

 fruit in all boxes after 28 days in storage. 



Figure 



-Golden Delicious apples stored 3 months at 31 c F.: A, Injured by exposure 

 to 3.25 p. p. m. of ozone: B, nonozonized. 



Corresponding injury was noticed on Rome Beauty apples that were 

 being used for inoculation studies after they had been in the ozonized 

 atmosphere for 30 days. Xone of the Winesap apples, however, showed 

 any injury upon removal from storage on March 3. On May 24 only 

 slight injury was discernible on 10 percent of the fruit and none was 

 serious enough to be considered objectionable to consumers (table 10). 

 On March 3. 1.3 percent of the Delicious apples were sufficient ly dam- 

 aged to make them objectionable, whereas on April 28. after 7 day- at 

 70° F., 67.8 percent of the red fruit and 17.4 percent of the green 

 fruit of the Arkansas variety were objectionable. 



Si lire the injury just described was produced by long exposure 

 to relatively low ozone concentration^ a te-t was made to determine 

 whether fruit injury would occur after short exposures to relatively 

 high concentrations of ozone. A box of Rome Beauty apples was 

 placed in an empty storage room and the ozonizer was operated for 



