Smock and Neubert (111) also linked scald with volatiles. When Rhode 
Island Greening apples were stored with other varieties, 91 percent of the 
Greening scalded; stored alone 36 percent scalded; and stored alone in a room 
with an air purifier only 1 percent scalded. Southwick (115) reported a pos- 
sible relationship of scald and volatiles, when he found high volatile produc- 
tion from McIntosh in 1941 and much scald. In 1942, less volatiles were pro- 
duced and less scald developed. Thompson and Huelin (127) found that early 
picked fruit gave off less volatiles than late-picked fruit, even though early 
picked fruit is more scald susceptible. 
Fidler and North (17) found that ethylene, present in or added to apple 
storages, did not increase scald. Stoll (124) pointed out that whether vola- 
tiles induce scald or not depends on their chemical nature, their concentration, 
and the duration of their action. However, the resistance of the skin, which 
varies with its structure, its composition and its physiological age, appears 
to be of equal importance, Hilkenbaumer (42) found that absorption of aromatic 
volatiles by the cuticle contributes to the development of scald and by removing 
them from the cuticle by scrubbing, scald can be avoided. Buchloh (6) suggested 
that scald is caused by a substance in the skin, which becomes toxic during long 
storage at low temperatures, but is diffused from the skin under conditions of 
alternating temperature or forced ventilation. 
Several other investigators have studied the chemistry of volatiles and 
137). Okamoto (63) produced a scald-like injury by treating apples with formic 
acid, acetic acid, amyl alcohol, hexyl alcohol, and esters containing 6 to 8 
carbon atoms. Huelin and Kennett (44) tested the effect of 19 volatile products 
on scald development. At a concentration of 1 mole in 10,000 moles of air, only 
butyric and caproic acids, and butyl and hexyl acetates significantly increased 
scald in fruit protected with oiled wraps. 
Effect of Weather 
Scald susceptibility varies markedly from season to season. Scald is 
usually most severe in years when the climate is hot and dry during the last 
few weeks of the growing season (52, 106, 131). In England, Fidler (15) found 
a strong correlation between scald in storage and high evaporation in relation 
to the amount of rainfall before harvest. Uota (131) controlled the temperature 
around the branches of McIntosh trees during the last 3 weeks before harvest. 
He reported that high night temperatures gave 100 percent scald and low night 
temperatures, only 2 percent. Work of a similar nature by Merritt and others 
(58) and Morris, Merritt, and Stiles (60) showed preharvest air temperature to 
be an important factor. Scald susceptibility, was greatly reduced after a suf- 
ficient number of hours below 50° F. had elapsed before harvest. With Stayman 
apples, storage scald was minimized if picking was delayed until 150 hours of 
temperature below 50° had accumulated after September 15. 
Effect of Nutrition 
Relatively little new experimental data is available on the effect of 
orchard nutrition on scald. Southwick, Weeks, Drake and Olanyk (118) reported 
that foliar levels of nitrogen of 2.26 percent and higher increased the sus- 
ceptibility of Red Delicious to scald in comparison to fruit from trees having 
an average leaf nitrogen of 2.12 percent on a dry-weight basis. Similarly, 
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