The spore-population samples were taken at the time of the experi- 

 mental fruit washing, which was approximately 2 hours after the close 

 of the day's commercial washing. The low population of viable spores 

 in the tanks suggested the possibility that many spores had been 

 killed by the chemical solutions in the interim between the commer- 

 cial and the experimental washings. To obtain further information 

 on this point, samples were taken during the course of commercial 

 washing on the afternoon of November 1 and again 2 hours after com- 

 mercial washing had ceased. The data (table 8) show that there were 

 no outstanding differences between the commercial and the experi- 

 mental washings with regard to spore populations. At the temper- 

 atures employed the washing solutions were evidently sufficiently 

 lethal to prevent an appreciable accumulation of viable spores (1 , 24) • 

 The low population of spores of blue mold and other apple-rotting 

 fungi in the washing tanks undoubtedly was partly responsible for the 

 low percentage of decay encountered in the 1941 experimental lots 

 (table 7). 



Table 8. — Spore population in washing solutions and rinse water used on Delicious 



apples harvested Sept. 22, 1941 



[All temperatures in ° F.] 





Sample A 



Sample B 



Date, treatment, and washing solution 



Total 



spores per 

 cubic centi- 

 meter 



Blue mold 

 spores per 

 cubic centi- 

 meter 



Total 

 spores per 

 cubic centi- 

 meter 



Blue mold 

 spores per 

 cubic centi- 

 meter 



Sept 22 (immediate treatment): 



Sodium silicate (63 pounds to 100 gallons) at 110° 

 Hydrochloric acid (1-percent) at 100° 



Number 

 

 10 

 7,000 



10 







5,800 



80 







8,200 



210 



10 



5,100 



Number 

 

 

 20 





 

 10 



10 

 

 10 



40 

 

 



Number 











5,900 











7,700 



90 



10 



5,600 



140 







4.900 



Number 

 

 

 10 



Oct. 6 (2-week delay treatment): 



Sodium silicate (63 pounds to 100 gallons) at 110°--_ 

 Hydrochloric acid (1-percent) at 100° _ 





 



Rinse water . - - _ .. _ _ _ . 



10 



Nov. 1 (6-week delay treatment) : 



Sodium silicate (63 pounds to 100 gallons) at 110° 



10 



o 





10 



Commercial wash: i 



Sodium silicate (63 pounds to 100 gallons) at 110°--. 



10 



o 





10 







i The samples for this determination were taken during the commercial operation of the washing machine, 

 several hours prior to the experimental washing. 



FUNGI ISOLATED FROM INFECTED FRUIT 



No difficulty was encountered in distinguishing the lesions produced 

 by Penicillium expansum (fig. 1) from those caused by other fungi. 

 However, for verification a number of isolations were made from le- 

 sions classified as blue mold infections, and isolations were made from 

 all infections which appeared to be caused by other pathogens. 



The isolations from the lesions attributed to Penicillium expansum 

 in all cases yielded this species. Isolations from lenticel infections 

 which appeared different from blue mold yielded Phialophora malorum 

 in all but one case; in this an unidentified species of Penicillium was 

 obtained. The fungi isolated from lesions centered at other infection 

 courts included the following in descending order of frequency: 

 Penicillium expansum, Botrytis cinerea, Phialophora malorum, Hormo- 

 dendrum cladosporioides (Fr.) Sacc, Alternaria sp., and Neojabraea 

 perennans. 



18 



