Nov. 12, 1917 
Jonathan-Spot and Scald of Apples 
295 
The results indicate that the dead-skin areas produced by apple-scald 
furnish an excellent opportunity for attacks by the common rot fungi. 
According to the observations of the writers, Alternaria sp. is more likely 
to infect scalded tissue than any other rot-producing fungus. Unfor¬ 
tunately cultures of this fungus were not available for inoculation at 
the time of the above experiment. It will be recalled that Jonathan-spot 
tissue was found to be particularly susceptible to the attacks of Alter¬ 
naria sp. 
EFFECT OF TEMPERATURE ON APPLE-SCAED 
Numerous experiments have been reported on the effect of temperature 
upon apple-scald. Powell and Fulton (17) found that prompt refrigera¬ 
tion was important in the prevention of apple-scald, but Greene (11) re¬ 
ported that holding the temperature high 
enough to permit the fruit to continue ripen¬ 
ing delayed the appearance of scald and found 
that Grimes apples scalded much less when 
they were not stored immediately after pick¬ 
ing. Some writers have reported that scald is 
worse in cold storage than in cellar storage, 
while others have found that the reverse condi¬ 
tion apparently held. 
In the fall of 1915 and again in the fall of 
1916 the writers carried out experiments to 
determine the effect of temperature on scald. 
The apparatus used in the experiments has 
already been described (p. 2 97). Great care was 
taken that the apples at the different temper¬ 
atures should be alike in size and maturity 
(p. 299). Arkansas, Baldwin,Grimes,Jonathan, 
Northwestern, and York Imperial apples were 
used. The results obtained on the last three 
varieties are given in figures 9 to 16. The experiments made on the 
other varieties were not so complete nor the scald so bad, but the 
results were in agreement with those reported. In all of the figures the 
base line represents temperature centigrade and the perpendicular the 
per cent of scald. In obtaining records on the degree of scald the 
maximum scald that had been observed to occur on the variety was 
taken as 100 and the. amount of scald in a particular case was measured 
by its relation to this standard. Both the area and the depth of the 
scald were considered. A record was made by two observers; and 
where differences occurred, the average was taken. The notes were made 
without reference to previous records. The amount of scald on the differ¬ 
ent apples at a particular temperature was remarkably uniform. In the 
early stages of scald at the higher temperature the apples took on a dry, 
russet appearance that was at first classed as distinct from the usual form 
too 
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TEMPERATURE CENT/GRADE 
Fig. 9.— Graphs showing the effect 
of temperature on apple-scald at 
the end of 9, 12, and 15 weeks. 
The dotted graph shows the 
amount of scald 3 days after re¬ 
moval from storage at the end of 
the is weeks. The apples were 
Jonathan and the same as re¬ 
ferred to in figures 2, 4, and 5 of 
the Jonathan-spot experiments. 
The results were similar for the 
different lots, and the average 
given is in the above graphs. 
