The tendency to develop internal browning is inherent in the fruits at 
harvest, but depends on storage temperatures of 30° to 32° F. in order to de- 
velop. Susceptibility seems increased in fruits that are large, or from light 
crops, those harvested late, or delayed in reaching storage. 
Ryall and Uota (145) tested the effect of sealed polyethylene (150 gage) 
film liners on the occurrence of internal browning and general storage life of 
Yellow Newtown apples grown in the Pajaro Valley of California. Test and check 
lots were stored at 31° and 40° F. No serious internal browning occurred at 
40°, but control was not ascribed to the film liners. 
Jonathan Spot 
Jonathan spot, a physiological disease, occurs on susceptible varieties 
wherever apples are grown. Jonathan spot is primarily a storage disorder asso- 
ciated with aging. While the disorder is worse on the Jonathan variety, it 
occurs frequently on Northern Spy, Rome Beauty, Winter Banana, and Golden Deli- 
cious and has been observed on a number of other varieties. In reporting the 
disorder on varieties other than Jonathan, there has been a tendency to intro- 
duce other names such as "Spy spot," "physiological spot," and ''senescent spot" 
as synonyms of Jonathan spot. 
Baker and Maxie (10) reported that Red Rome Beauty apples in storage are 
frequently subject to a physiological disorder characterized by small superfi- 
cial brown or black spots at the lenticels. They state that the disorder re- 
sembles Jonathan spot and Spy spot. Ina preliminary study they found that a 
combined treatment of activated charcoal and one-half pound of oiled paper per 
bushel retarded the spotting. 
Smock (151) reported that "Spy spot'' (Jonathan spot) was worse on the 
blush than the pale part of the fruit. He found that ringing large limbs caused 
the fruits thereon to be redder and more susceptible to Jonathan spot than 
fruits from nonringed limbs. Fruits from the outside of the trees were more 
susceptible than those from the shaded, inner portion. The disorder was worse 
on Northern Spy apples stored at 40° F. than on those stored at 32°. Air puri- 
fication did not give control so Smock reasoned that volatiles were not the 
cause. Control was obtained by storing the apples in controlled atmosphere of 
about 5 percent carbon dioxide and 2 percent oxygen at 40°, (See section on 
Controlled-Atmosphere Storage, p. 89.) 
Tomana (166) found that in plots with heavy nitrogen and phosphorous 
fertilizer applications, leaves and fruit tissues contained the most nitrogen 
and fruits spotted most severely. Earlier harvested fruits developed more 
Jonathan spot than late-harvested fruits. He states that open lenticels are 
necessary for Jonathan spot development, and that the primary cause of Jonathan 
spot is the infiltration of water through open lenticels. He believes that 
browning of the skin tissues of the spot are due to the oxidation of phenolic 
substances, chiefly l-epi-Catechin, by polyphenol oxidase. 
Research workers in the United States do not consider that the nature of 
Jonathan spot is clearly understood, but its appearance on apples is believed 
indicative of a stage of senescence. Traas (167) states that Jonathan apples 
that are deeply colored, large, and picked late are most susceptible to Jonathan 
spot. He found that intensity of spotting was affected by the storage tempera- 
ture and the degree of spotting when the fruits were stored. 
Van Hiele (170) found the least Jonathan spot on Jonathan apples har- 
vested early and stored immediately. 
aT) 
