UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 1104 



JUf^'^^U 



Washington, D. C. 



October 23, 1922 



INTERNAL BROWNING OF THE YELLOW 

 NEWTOWN APPLE/ 



By W. S. Ballabd, Plant Pathologist, Office of Fruit-Disease Investigations, and 

 J. R. Magness and Lon A. Hawkins, Plant Physiologists, Office of Horticul- 

 tural and Pomological Investigations, Bureau of Plant Industry. 



CONTENTS. 



Page. 



History of the investigations 1 



Description of internal browning — 4 



Experimental work 6 



Relation of internal browning 



to storage conditions 8 



Relation of internal browning 



to orchard conditions 12 



Relation of internal browning to 



soil fertility and fertilizers 14 



Page. 

 Experimental work — Continued. 



Relation of internal browning 



to the individual tree 16 



Defoliation and girdling ex- 

 periments 17 



R6sum6 of factors conducive to 



internal browning 22 



Conclusion 23 



Summary 23 



HISTORY OF THE INVESTIGATIONS. 



It has been recognized for a number of years that certain apples 

 grown under particular climatic conditions and held in cold storage 

 at temperatures around 32° F. are liable to develop a peculiar brown- 

 ing of the tissue of the fruit. This trouble has no external symp- 

 toms and can not be detected from the outside of the fruit. It was 

 first brought to the attention of investigators of the Bureau of Plant 

 Industry during the storage season of 1905-6. In the fall of 1905 a 

 series of storage experiments with apples from various sections of 

 California was begun under the direction of G. Harold Powell. On 

 examination of the fruit in the spring of 1906, apples from the Pa- 

 jaro Valley were found to be affected by this premature browning 

 of the flesh, which was designated as internal browning. 



1 This bulletin reports the results of cooperative work between the Offices of Fruit- 

 Disease Investigations and Horticultural and Pomological Investigations of the Bureau 

 of Plant Industry. C. W. Mann, E. M. Harvey, and H. R. Kraybill, formerly members of 

 the staff of one or the other of these offices, and C. F. Kinman and H. C. Diehl, now 

 with the Office of Horticultural and Pomological Investigations, have materially as- 

 sisted in experimental work in this investigation. 



919°— 22- 



