294 
Journal of Agricultural Research 
Vol. XI, No. 7 
necessarily follow that the spots that develop under orchard conditions 
would obey the same law. 
APPLE-SCALD 
“Scald” is a term applied to a superficial browning that often occurs 
on apples in storage. Usually only the five or six surface layers of cells 
that form the color-bearing tissue of the apple are affected, but in 
aggravated cases the trouble may extend entirely through the firmer 
skin layer of the apple into the large isodiametric cells of the pulp. In 
such cases the flesh becomes soft, brown, and rotlike, and the trouble is 
sometimes spoken of as “ deep-scald.” Deep-scald has been of more com¬ 
mon occurrence on York Imperial than on Grimes. 
It will be noted that in the earlier and more typical cases of scald the 
tissue affected is the same as with Jonathan-spot. The skin color in 
the case of scald, however, is a light rather than a dark brown, the areas 
affected are always larger, and the demarcation between diseased and 
healthy tissue less definite than in the case of Jonathan-spot (PI. 32 
and 33). 
SCALD AS A SOURCE OF ROT INFECTION 
The fact that the protective skin layers of the apple are broken down 
in the case of scald naturally suggests the importance of the disease in 
paving the way for the attacks of fungi. The writers had often observed 
cases where apple rots appeared to follow scald, but it seemed desirable 
to make an experimental determination of the relation of scald to rot 
infection. The test was made on Grimes apples that had been used in 
the aeration and humidity experiments reported later. The scalded fruit 
had been picked at the same time and stored at the same temperature 
as the unscalded, but had received poorer aeration. The apples were 
washed in heavy spore suspensions of the fungus in the manner already 
described in the rot experiments on Jonathan-spot. Ten scalded and ten 
scald-free apples were used with each fungus. The experiment was 
started on November 7. Table II shows the results obtained with 
Glomerella cingulata after two weeks, and with Penicillium expansum and 
Sclerotinia cinerea after three weeks. 
Tabi^e II .—Relation of apple-scald to infection by apple rot fungi 
Fungus. 
Number of infections 
on— 
Scalded 
apples. 
Scald-free 
apples. 
Glomerella cingulata .. 
9 
10 
8 
0 
1 
O 
Penicillium expansum . 
Sclerotinia cinerea . 
