A STUDY OF THE INTERNAL BROWNING OF THE 
YELLOW NEWTOWN APPLE ‘ 
By A. J. Winkler 
Associate in Viticulture, formerly James Rosenberg Memorial Scholar in Agriculture, 
California Agricultural Experiment Station 
INTRODUCTION 
As a result of the heavy losses of Pajaro Valley apples during the 
early development of cold storage practices in California, considerable 
effort by the Bureau of Plant Industry of the United States Depart¬ 
ment of Agriculture has been directed toward determining the cause 
of this trouble and toward devising methods of overcoming it. In 1910 
Stubenrauch {i 6 y indicated a relation between the browning and the 
temperature of storage, lower temperatures favoring its development. 
In the report of this bureau for 1920 (j) it was stated that there was 
no relation between the acidity of the fruit and the trouble and that 
as yet no definite cause could be assigned for this disease. 
OBJECTS OF THE INVESTIGATION 
The present investigation is an attempt to determine the cause of 
internal browning, wiA special reference to (i) field conditions which 
are responsible for the susceptibility of the fruit and (2) the internal 
and external factors which are immediately responsible for its develop¬ 
ment in storage. 
DESCRIPTION OF INTERNAL BROWNING 
Internal browning as it occurs in the Yellow Newtown apple is a 
nonparasitic storage disease of the large isodiametric cells of the pulp. 
In apples stored immediately, regardless of the time of harvest, at 
— I.I® and o® C. the browning generally becomes noticeable during 
the latter part of December, while in apples stored at higher tempera¬ 
tures its fimt appearance is proportionately later. The writer has not 
observed its occurrence in apples kept at temperatures of 8.3° or above. 
In a cross-sectional view of the apple, the disease is fiurst detectable 
in more or less elongated areas radiating outward from the central 
portion of the apple in the region opposite the basal end of the carpels. 
By cutting the apple in various planes it is apparent that the areas 
first browned lie adjacent to and radiating outward from the primary 
vascular bundles. 
As the browning becomes more severe, it spreads most rapidly in 
the region of the secondary vascular bundles. In many specimens it 
* Accepted for publication July 17, 1922. Submitted as a major thesis to the faculty of the Graduate 
Division of the University of California, May, 1921, in partial fulfillment of the requirements for the degree 
of doctor of philosophy. 
* The writer wishes to express his thaxilcs to Dr. J, C. Whitten, Dr. J. P. Bennett, and Prof. E. L. 
Overholser for counsel and suggestions during the progress of this investigation. The writer is also indebted 
to Mr. H. E. Jacob, a graduate student, for assistance in harvesting the fruit, in preparing it fw Stonge, 
and in making the observations. 
* Reference is made by number (italics) to ** Literature cited*’’ P. 284. 
Journal of Agricultural Research, Vol. XXIV, No. * 
Washington, D. C. Apr. 14,1923 
acv Key No. Cauf 
(165) 
f.-32 
