24 BULLETIN 1104, U. S. DEPARTMENT OF AGRICULTURE. 



There is usually a sharp increase in the percentage of browning 

 in the fruit following its removal from cold storage. 



Internal browning develops mainly in those orchards having high' 

 soil fertility and located in the California coastal fog belt, where 

 the humidity is high and there is little sunshine. 



It has not been possible to produce internal browning in apples 

 or to prevent its appearance by any one of several fertilizer treat- 

 ments carried out in orchards during a period of four years. 



Internal browning of apples varies widely in the fruit from in- 

 dividual trees during any single year, and a given tree does not 

 produce year after year fruit tending to become browned when 

 put in storage. Often a tree will produce sound fruit one year 

 and fruit that becomes badly browned the year following. 



Apples of large size, high in sugar and acid content, and from 

 branches girdled during the growing season tended to become 

 browned to a much greater extent than normal fruit from the same 

 tree. Apples from branches partially defoliated showed markedly 

 less browning than fruit from branches with normal foliage. 



Internal browning develops mainly in apples from trees growing 

 under the environmental conditions described during seasons when 

 the crop on the tree is very light and the fruit tends to large size 

 and coarse texture. When a heavy crop is produced, little internal 

 browning seems to develop. With a light crop of large-sized apples, 

 holding the fruit at 36° F. or above will prevent serious loss from 

 this trouble in cold-stored Yellow Newtown apples. 



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