Washington, D.C. Vv October 23, 1922 
INTERNAL BROWNING OF THE YELLOW 
NEWTOWN APPLE.’ 
By W. S. BaLuArD, Plant Pathologist, Office of Frutt-Disease Investigations, and 
J. R. Maeness and Lon A. Hawkxtns, Plant Physiologists, Office of Horticul- 
tural and Pomological Investigations, Bureau of Plant Industry. 
CONTENTS. 
Page. Page. 
History of the investigations ____~~ 1 | Experimental work—Continued. 
Description of internal browning-- 4 Relation 'of internal browning 
Mxpermicntal work _~ )_:i2 —-* + 6 to the individual tree___~__~_ 16 
Relation of internal browning Defoliation and girdling ex- 
to starace conditions———--.=_ 8 PCTIMEMES! 2a a ere ee 17 
Relation of internal browning Résumé of factors conducive to 
to orchard conditions_____~~ 12 internak browning, 2=—. 2 22, 
Relation of internal browning to Conclusion——=—_— sat eRe NE OS a3 
soil fertility and fertilizers__ LAVAS Summary se tte re A See ee 2 
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 foyind to be affected by this premature browning 
of the flesh, which was designated as internal browning. 
1This 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 
sisted in experimental work in this investigation, 
as- 
919°—22——1 
