705426 



immediate washing. Cold storage for 2, 6, or 10 weeks prior to wash- 

 ing resulted in increased resistance to washing injury, the increases in 

 general being proportional to the length of the storage period. When 

 fruit was held for 6 weeks prior to washing, its resistance to infection 

 was consistently increased. 



Fruit packed while wet developed no more decay than that dried 

 before packing. 



Passing apples through a heavily contaminated washing solution 

 followed by a relatively clean rinse caused only a slight increase in 

 the amount of decay, whereas subjecting the unwashed fruit to a 

 special rinse containing a high population of blue mold spores resulted 

 in a greatly increased number of infections. 



Lenticels and washing injuries constituted the principal courts of 

 infection in apples subjected to a severe dual-process washing treat- 

 ment. Milder treatments resulted in an approximately equal dis- 

 tribution of the infections between lenticels and mechanical injuries; 

 in unwashed fruit mechanical injuries predominated in promoting 

 invasion. 



Susceptibility to blue mold infection varied in fruit from different 

 orchards and in that from the same orchard during successive seasons. 



No clear-cut relation could be found between the number of open 

 lenticels, as determined by dye penetration, and the number of infec- 

 tions that developed at lenticels. However, a severe washing process 

 was found to increase both the number of open lenticels and the num- 

 ber of lenticel infections. 



In addition to true lenticels, many other minute lenticellike open- 

 ings that served as avenues of infection were found in the skin of 

 the fruit. Some of these resulted from the washing process, but 

 the origin of others was obscure. 



The importance of careful handling in the control of blue mold 

 decay is emphasized by the fact that many of the lenticel infections 

 occurred in bruised areas. 



Although a number of fungi were isolated from lesions originating 

 at mechanical injuries, only Phialophora malorum (Kidd and Beaum.) 

 McColloch in addition to blue mold was found to have penetrated 

 the fruit lenticels. 



MATERIALS AND METHODS 



Apples for the 1938 investigations were obtained from an orchard 

 in the Wiley Heights district of the upper Yakima Valley of Wash- 

 ington. The fruit from this orchard had developed excessive amounts 

 of lenticel infection in previous seasons. It was harvested at optimum 

 maturity and sorted so as to be comparable with commercially packed 

 fruit. Immediately or after various delay periods replicate samples 

 were washed in a dual-process flood washer, first with sodium silicate 

 (80 pounds to 100 gallons) at 100° F. and then with 1.5-percent hydro- 

 chloric acid at 80°. The period in each solution was 30 seconds. 

 After washing, the fruit was dipped in a water suspension of blue 

 mold spores, packed wet or dried overnight before packing, and 

 stored at 32°. 



The procedure was changed during 1939 and 1940 so that, instead 

 of replicate samples from a single orchard, the fruit was obtained 

 from five different orchards in the upper Yakima Valley. Handling 

 methods were essentially the same as those employed in 1938 with 



