6 BULLETIN 587, U. S. DEPARTMENT OF AGRICULTURE. 
affect only the external appearance of the fruit and are usually desig- 
nated as skin blemishes and (2) those that injure the flesh of the 
fruit and are known as decays. Only those of considerable economic 
importance to the successful storage of northwestern apples will be 
described. For the sake of convenience in reference the most im- 
portant factors governing the development and prevention of these 
various troubles in storage are briefly discussed here. The recom- 
mendations made are based on investigational results and also on com- 
mercial experience if such experience is available and considered 
reliable. 
SKIN BLEMISHES DEVELOPING IN STORAGE. 
The most important skin blemishes are (1) scald, (2) Jonathan 
spot, (3) soft scald, (4) scab, and (5) bitter-pit; but there are others 
which are omitted because of their infrequent occurrence and relative 
economic unimportance in the Pacific Northwest. The importance of 
skin blemishes can not be overestimated, especially in the marketing 
of a crop such as the Pacific northwestern apple crop. It is safeto | 
say that more than 25 per cent of all northwestern apples in cold stor- 
age are seriously affected by skin blemishes. 
FACTORS AFFECTING THE DEVELOPMENT OF SCALD IN STORAGE. 
Scald is the most prevalent and most serious of the skin blem- 
ishes. It is a browning or blackening of the skin that does not 
extend into the flesh, but gives the fruit a scalded or baked appear- 
ance. Naturally this greatly lessens its commercial value. Plate 
II illustrates its appearance on Rome Beauty. Commercially scald 
can not be controlled absolutely, but through proper care in har- 
vesting and storing it can be reduced greatly, and in this connec- 
tion the following results of the experimental work are important: 
(1) Striking differences are found in the susceptibility of varie- 
ties to scald. Probably no variety is absolutely immune. Rainier, 
Northern Spy, Jonathan, Hyde King, Esopus, and Missouri are 
comparatively so, while the Arkansas, Rome, Wagener, and others 
often develop an undue amount. Between these extremes come most 
of the more commonly grown varieties, and the susceptibility of 
these to scald varies greatly under the different conditions described 
below. 
(2) There is a very appreciable decrease in the amount of scald 
on apples stored immediately as compared with those stored after 
a delay of two weeks. The amount of scald on the fruit stored imme- | 
diately and that delayed two weeks before storage varies greatly 
with the weather conditions to which the delayed lots are subjected, 
and in cold weather there may be but little difference. 
(3) Apples held at 32° F. scald slightly less than those stored at 
35° F. or in common storage. 
