DECAY IN COMMERCIALLY PACKED FRUIT 

 Development and Types of Decay 



The results of the test conducted in 1941 with relatively large 

 quantities of naturally contaminated apples handled, washed, and 

 packed under commercial conditions are shown in table 7. Although 

 this fruit developed very little decay, the results corroborate those 

 obtained in previous years with artificially inoculated apples. Only 

 48 (0.59 percent) of the 8,099 fruits used in the experiment showed 

 decay after storage for V/i months. Of the apples washed immediately 

 0.83 percent developed decay, while of those held 2 and 6 weeks in cold 

 storage before packing 0.51 and 0.43 percent, respectively, did so. Of 

 the fruits held in cold storage before washing, none showed decay at 

 time of washing after they had been stored for 2 weeks, and only 2 

 infected fruits were found at time of washing after they had been 

 stored for 6 weeks. Because of mechanical injuries these 2 apples 

 probably would have been sorted out regardless of the decay. 



Only two lenticel infections developed in the fruit that was packed, 

 and these occurred in the fruit delayed for 6 weeks before washing. 

 Blue mold decay was slightly more prevalent than gray mold rot caused 

 by Boirytis cinerea Fr., and the decay caused by Phialophora malorum 

 was third in importance. Most of the blue mold infections were at 

 small punctures, whereas the gray mold centered at the calyx. It is 

 possible that some of the gray mold infections were at washing injuries 

 in the calyx basin; however, in some instances the fungus appeared to 

 have attacked the sepals first and then to have advanced into the tissue 

 of the fruit. Inasmuch as the apples had sufficient open lenticels and 

 washing injuries to permit considerable infection, the small amount of 

 blue mold decay probably was due to the low population of spores 

 presumably carried by the fruit at the time of packing. 



The amount of washing injury visible after storage was much greater 

 on fruit washed at harvesttime than on that delayed for 2 or 6 weeks 

 in cold storage before washing. Washing injury incurred after the 

 6-week delay was not appreciably different from that found on fruit 

 stored for only 2 weeks prior to washing. 



The relation of fruit size to decay can be summarized from table 7 

 as follows: In boxes containing 72 to 80 apples, 1.14 percent of the 

 fruits were decayed; in those containing 88 to 100 apples, 0.65 percent; 

 and in those containing 113 to 125 apples, 0.39 percent. These results 

 substantiate observations made during the 2 preceding years that 

 larger fruit is more susceptible to infection than smaller fruit. 



Spore Population of Washing Solutions 



To determine the spore population in different compartments of the 

 washing equipment used in 1941, dilution cultures were prepared from 

 samples of solution taken from the various tanks. As shown in table 8 

 the acid and alkaline washing solutions had very low concentrations 

 of fungus spores and the rinse tank, although fairly heavily contam- 

 inated, contained relatively few blue mold spores. A study of the 

 colonies that developed in the dilution plates revealed that most of 

 the spores belonged to the following genera: Dematiwn, Trichoderma, 

 Phoma, Cladosporiwn, and Phialophora. Only the last two genera 

 contain important apple-decaying species. The gray mold fungus, 

 Botrytis cinerea, was found only rarely. 



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