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



in 1918 about 19,000 acres of orchards, practically all in bearing. 

 The production for that year was approximately 4,500,000 packed 

 boxes, or more than two-thirds of the apple crop of the State. The 

 Yellow Newtown comprises more than half of the production of the 

 district, while the Red Pearmain, another very susceptible variety, 

 constitutes probably about one-thirtieth of the total output. A large 

 part of the Yellow Newtown crop is marketed within the State, a 

 portion is shipped to the central and eastern United States, and con- 

 siderable quantities are exported. The bulk of the crop is packed 

 in boxes and placed in cold storage, inasmuch as the Yellow New- 

 town is a long-keeping variety, capable of retaining its quality until 

 late winter or early spring. It is evident from this description that, 

 considering the total apple production of the United States, the 

 percentage of the crop in danger of serious depreciation on account 

 of internal browning is not large. Great financial losses, however, 

 have resulted in the past to the apple growers of the Pajaro Valley 

 from this deterioration of the stored fruit. It is therefore vitally 

 important' to the prosperity of this district that this trouble be 

 investigated and methods worked out for its control. 



So little has been written about this particular storage trouble 

 that it has acquired no well-established name in commercial circles. 

 It is sometimes referred to by the trade as " dry-rot," but that name 

 is inappropriate, for the reason that the diseased tissue shows no 

 noticeable drying out. The term " internal browning " was chosen 

 because it suggests the appearance of the diseased tissue and also its 

 location in the flesh of the apple. Since this internal browning de- 

 velops only in low-temperature storage, the term " storage internal 

 browning " would be more descriptive but is probably too long to 

 come into general use. 



DESCRIPTION OF INTERNAL BROWNING. 



Careful investigations have established the fact that internal 

 browning is not caused by a fungous or bacterial parasite. It is the 

 result of certain abnormal physiological activities in the flesh of the 

 apple classed in the general group of so-called physiological diseases. 

 Internal browning does not appear in the fruit on the trees and does 

 not develop if the apples are held at room temperature after picking. 

 Regardless of some opinions to the contrary, it is not possible to 

 predict from the external appearance of an apple whether or not 

 internal browning will be found when the apple is cut open. In 

 other words, internal browning does not manifest itself by any 

 abnormal appearance of the skin of the fruit. It will be noted that 

 this character is in contrast to the conditions obtaining in some other 



