SOME EFFECTS OF THE BLACKROT FUNGUS, SPHAE- 
ROPSIS MALORUM, UPON THE CHEMICAL COMPOSI¬ 
TION OF THE APPLE 1 
By Charles W. Culpepper, Biologist, West Tennessee State Normal School; Arthur 
C. Foster, Assistant in Botany , North Carolina Agricultural and Mechanical College; 
and Joseph S. Caldwell, Specialist in Fruit By-Products Investigations, Washington 
Agricultural Experiment Station 
INTRODUCTION 
Various investigators have concerned themselves with the taxonomy, 
morphology, and life history of Sphaeropsis mcUorum Peck. This fungus 
occurs upon the twigs and branches of the apple (Malus sylvestris ), produc¬ 
ing cankers (15); 2 upon the foliage, where it produces a characteristic leaf- 
spot (22, 24); and upon the fruits, where its growth results in a decay 
that is unique because the diseased tissues undergo a rapid and charac¬ 
teristic blackening, because there is neither softening nor breaking down 
of the affected areas, and because loss of water and consequent shriveling 
do not begin until some time after the entire fruit has become involved. 
The occurrence of the disease upon the fruits of the apple appears to be 
very much less common in the North and East than in the South, where 
it frequently destroys 25 to 50 per cent of the crop (27). 
The fact that the organism is able to attack tissues which vary so 
widely in chemical composition indicates that a study of its physiology 
should yield results of considerable interest. Very little attention has 
thus far been paid to the nature and extent of the chemical changes 
produced in the fruit by this organism, and it was to obtain information 
in regard to these changes that the present study was undertaken. 
The present paper presents the results of a quantitative analytical 
study of the chemical composition of normal mature apples in comparison 
with others of the same variety attacked by Sphaeropsis malorum. The 
work was done in the laboratories of plant physiology of the Alabama 
Polytechnic Institute and Agricultural Experiment Station in the summer 
and autumn of 1915. The problem was suggested to Messrs. Foster and 
Culpepper, who were at that time graduate assistants in the laboratory, 
by Dr. Caldwell, who outlined the general methods of study to be em¬ 
ployed and supervised the work. The major portion of the analytical 
work was done by Messrs. Foster and Culpepper. Upon their removal to 
other laboratories at the end of the summer, certain portions of the 
analyses were necessarily left incomplete; these have been completed, 
1 Published with the permission of the Director of the Alabama Agricultural Experiment Station. 
2 Reference is made by number to “ Literature cited,” p. 39-40. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
fo 
(! 7 ) 
Vol. VII, No. 1 
Oct. 2,1916 
Ala.—3 
55855°—16 - 2 
