caused by blue mold (PenicilHum expansvm Lk. emend. Thorn), 

 despite the fact that mechanical injuries such as stem punctures and 

 box cuts have been greatly reduced in commercially packed fruit. 

 One of the reasons that serious decay losses continue is that lenticels 

 and other microscopic breaks in the skin frequently serve as avenues 

 of infection (fig. 1). Some of the factors related to the infection of 



apples at lenticels 

 have been investigat- 

 ed by other workers, 

 but little has been 

 known of the effect of 

 various washing and 

 storing practices on 

 the susceptibility of 

 the fruit to this type 

 of fungus invasion. 



The studies report- 

 ed in this circular 

 were conducted dur- 

 ing the period from 

 1938 to 1943 to deter- 

 mine the effects of 

 certain handling 

 practices on the de- 

 velopment of blue 

 mold decay in Deli- 

 Figure 1. — Lenticel decay caused by blue mold. cious apples. Of pri- 

 mary concern was 

 the problem whether cold storage prior to washing and packing results 

 in increased washing injury and decay. Other factors investigated 

 were the severity of the washing treatment, the drying of fruit prior to 

 packing, and the population of blue mold spores in the washing solu- 

 tions and rinse tank. In addition, a histological study of the skin of 

 the fruit was made to clarify some of the questions relative to the 

 penetration of lenticels and other microscopic openings by blue mold. 

 In general during the present study more open lenticels and greater 

 amounts of lenticel decay were found on washed than on unwashed 

 fruit when both were dipped in a suspension of blue mold spores 

 before they were packed. Unwashed fruit dipped in a spore suspen- 

 sion developed more lenticel infection than comparable washed fruit 

 packed without being dipped. Thus, it is evident that unwashed 

 fruit with a high natural spore population might develop more decay 

 than fruit washed under sanitary conditions and rinsed with plenty 

 of clean water, even though the washed fruit might be more susceptible 

 to decay. 



A delay of 3 days in a nonrefrigerated warehouse decreased the 

 susceptibility of the fruit to washing injury and blue mold infection. 

 Although such a delay cannot be recommended, it should be borne in 

 mind that increased decay and washing injury might occur if immedi- 

 ate washing and packing were put into general practice without con- 

 current precautions to reduce the spore population and the severity 

 of the washing treatment. 



No justification was found for the commonly held belief that wash- 

 Log and packing apples after they have been held for several weeks at 

 32 c F. make them more subject to washing injury and decay than 



