4. BULLETIN 1104, U. S. DEPARTMENT OF AGRICULTURE. 
in 1918 about 19,000 acres of orchards, practically all in bearing. 1 
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 © 
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