8 BULLETIlSr 1104, U. S, DEPAKTMENT OF AGRICULTURE. 



more pronounced than "'medium" and sufficiently marked to lower 

 the value of the fruit appreciably or even make it unsalable. The de- 

 scriptions on page 5 accompanying Plates I and II will assist the 

 reader in understanding the significance of the terms " trace," " me- 

 dium," and " bad " as used in classifying the intensity of internal 

 browning. It will be seen that these three classes grade from one to 

 another with no sharp distinctions between successive classes, so that 

 they serve only as a rough method of estimation. 



The method of inspecting the fruit and recording the internal 

 browning was as follows: Each apple was cut crosswise into ap- 

 proximately equal parts and the presence or absence of browning 

 was noted. If no browning appeared the apple was recorded as 

 sound regardless of any other imperfections that might be present. 

 If internal browning was present, a record of its location, whether 

 " core " or " tissue," and the extent, " trace," " medium," or " bad," 

 was made. The total number of apples cut from each box was 

 recorded and the records for each box and each tree were kept 

 separately. - 



For the most part the fruit has been held in commercial cold-- 

 storage houses. In one of these houses the air circulation system was 

 employed, air being cooled in a bunker room and circulated by fans 

 through the storage rooms and back to the bunker room again. In 

 the other plant each room was cooled by means of brine coils sup- 

 ported near the ceiling. In this case there was, of course, very little 

 air movement within the storage rooms and no effort at ventilation. 

 The concentration of carbon dioxid was sufficient at times to make it 

 impossible to light a match. No direct comparison was made of the 

 keeping quality of fruit stored in these two types of storage houses, 

 but from general observations there appeared to be no noticeable 

 difference. 



RELATION OF INTERNAL BROWNING TO STORAGE CONDITIONS. 



Previous to the year 1910 apples from the Pajaro Valley district 

 were stored at temperatures around 32° F., approximating cold- 

 storage temperatures used for apples throughout the United States. 

 At that time, however, certain observations by Stubenrauch and 

 other workers of the Bureau of Plant Industry led to the belief that 

 internal browning developed to a much greater extent at temjaeratures 

 near 32° than at 35° to 40° F. Consequently, after the year 1910 

 the commercial cold storages at Watsonville and other points in 

 California, where the tendency of this fruit to develop internal 

 browning in storage was known, raised the temperatures of their 

 apple-storage rooms to 35° F. With the 1917-18 storage season, the 

 temperature of storage was raised to 36° F. This is the temperature 



