Oct. 2, 1916 
25 
Effect of Blackrot Fungus on the Apple 
fruits showing just perceptible initial areas of tissue attacked by Sphaerop - 
sis malorum were removed from the tree, weighed, the stems carefully 
sealed with paraffin, the increase in weight due to this treatment noted, 
and the fruits kept under observation. They were again weighed when 
decay had involved approximately one-half the tissues of each fruit, 
and again as soon as decay had become complete. The weight of the 
normal fruits was 566 gm.; when half-decayed, this had been reduced to 
559 gm., or 98.76 per cent the original weight; when wholly decayed 
the weight was 539.6 gm., or 95.39 per cent of the original weight. In¬ 
asmuch as the moisture contents of the normal, half-decayed, and wholly 
decayed tissues taken for analysis were 87.39 P er cent, 86.62 per cent, 
and 86.14 per cent, respectively, of the total weights, it is obvious that 
the loss in weight is due principally to other causes than the escape of 
water, partial proof of which is given by the fact that in the apples from 
which these weights were obtained the stems had been sealed, while 
the peel of every fruit remained intact. 
Table I .—Composition of normal mature fruit of Red Astrachan apple 
Analyst. 
Source of fruit. 
Total 
solids. 
Ash. 
Acidity 
as malic. 
Crude 
fiber. 
Reduc¬ 
ing 
sugar. 
Cane 
sugar. 
Protein. 
Browne (i). 
State College, Pa. 
Percent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
15*30 
0-37 
1*038 
6.67 
6.98 
3*53 
O. TC 
Jones and Colver (7) 
Nonirrigated or¬ 
18.10 
•9457 
0.288 
chard, Idaho. 
Do. 
Irrigated orchard, 
14*73 
.890 
6.08 
.560 
Idaho. 
2 • 9 r 
Culpepper, Foster, 
and Caldwell. 
Auburn, Ala. 
12.94 
.2548 
.9288 
2 .10 
*574 
4*960 
■245 
A comparison of the transpiration of normal apples given similar 
treatment with that of decaying apples would lead one into error, 
since the release of energy resulting from decomposition would mani¬ 
festly increase transpirational water loss from the decaying fruits. 
While losses of weight due to transpiration and to respiration conse¬ 
quently can not be separately measured, it is clear from a comparison 
of the figures given that the primary and chief cause of loss in weight 
must be accelerated respiration. For these reasons, the analytical data 
now to be presented are in all cases based upon 100 gm. of fresh normal 
tissue, and have been corrected to this basis by the division of all figures 
for half-decayed fruit by 1.01255, of all figures for completely decayed 
material by 1.0492. These ratios are based upon the figures for losses 
in weight during decay obtained in the experiment just described, 
and the corrected figures are regarded as very close approximations to 
equal amounts of normal tissue, especially since the fruits employed in 
any one group of analyses were carefully selected for equal size and 
degree of maturity. Table II presents in tabular form a summary of 
the results of the analyses. 
