8 CIRCULAR 9 3 5, U. S. DEPARTMENT OF AGRICULTURE 



Ripeness During Storage 



Susceptibility to bruising damage increased with ripening of apples 

 (table 2), and the number of bruises that decayed after inoculation 

 increased with maturity and ripeness of the fruit (table 4) . Infected 

 bruises on overmature apples increased from 28 percent at harvest to 

 70 percent on apples that were bruised and inoculated late in March. 



The increasing susceptibility of bruised apples to decay with 

 advancing ripeness is an important consideration for the shipper who 

 is planning spring shipments of freshly packed apples. When late 

 packing is necessary, every precaution should be taken to prevent 

 bruising; exposure to decay fungi in packing-house operations should 

 be kept at a minimum; and the packing operation should be so 

 timed that packed fruit can be shipped and marketed in the shortest 

 possible time after packing. 



Time of Inoculation After Bruising 



During the 1948 study of the effect of ripeness on bruising damage 

 and decay, many of the bruises produced at harvesttime lost their 

 susceptibility to decay invasion when inoculated later in the storage 

 season (table 4). Since the reduction of susceptibility to decay 

 occurred prior to December 1, a study was made in 1949 to find how 

 soon after bruising the damaged tissue became resistant to decay 

 infection. 



In the experiment, one lot of apples was bruised and inoculated at 

 harvesttime and compared with other lots so treated after 3, 10, 17, 

 31, 45, and 75 days of storage at 31° F. Additional lots were bruised 

 at harvest, then inoculated after these same intervals of storage for 

 comparison with those freshly bruised and inoculated. Pressure 

 tests performed at harvesttime showed an average firmness of 15.3 ± 

 0.19 pounds, whereas the same tests at the end of the 75-day storage 

 period on apples comparable to those bruised and inoculated at 

 harvesttime, showed an average firmness of only 12.9 ±0.15 pounds. 

 This indicated that a significant softening of the apples had taken 

 place during the storage period. No statistically significant varia- 

 tion in size of bruises was noted on fruits bruised at intervals up to 

 and including 45 days after harvest. Braises produced 30 days later 

 (or at the end of the 75-day test period, which terminated approxi- 

 mately December 10) were significantly larger, indicating that there 

 was a marked correlation between loss of firmness of the apples and 

 bruise damage (table 5). 



Delayed inoculation after bruising resulted in less infection than 

 inoculation at the time of bruising (table 5). Twenty percent of the 

 bruises produced at harvesttime and inoculated with blue mold im- 

 mediately became infected, whereas only 2.5 percent of the bruises 

 made at harvest and inoculated after 3 days in storage decayed. On 

 the other hand, 57.6 percent of the bruises produced after 3 days in 

 storage and inoculated immediately became infected. No decay oc- 

 curred on fruit bruised at harvesttime and inoculated after intervals 

 in storage of more than 3 days, except in the lot inoculated after 31 

 days. In this lot, 10 percent of the inoculated bruises decayed. 



