Keijer and Dijksterhuis (80) reported that apples that were most subject 
to scald were also most subject to bitter pit. 
Sorensen (154) found that heavy pruning increased bitter pit. 
Some recent studies have been made on the cytology of pitted tissues, 
Working with Winter Banana apples Arnaud (3) found that bitter pit tissues are 
not corky in nature, but are probably the result of disturbances of the dehy- 
drogenase enzyme system. He also states that bitter pit symptoms can be masked 
by zinc applications. 
Buchloh, Baxter, and Neubeller (32) reported that starch grains remained 
in the area of bitter pit tissues in Cox's Orange Pippin long after it had dis- 
appeared elsewhere. They stated that in the early stages of bitter pit the 
fibers in the cell wall break down, and there is an aggregation of droplets 
which in healthy tissues are scattered through the cytoplasm. Pitted tissues 
had a higher percentage of certain fatty acids than healthy tissues, 
In studying the effect of fungicidal sprays in France, Paulin and Anquez 
(126) noted that bitter pit was most common on Reinette du Mans apples treated 
with ziram or zineb. 
Ginsburg (60), in South Africa, reported a relatively reliable method 
for detecting pit-susceptible apples. The sample of apples is subjected to 
90° F., in an atmosphere of 1 percent acetylene for 48 hours. The development 
of bitter pit from a latent stage is accelerated by the treatment, 
Brown Core 
Brown core, also known as core browning and in Australia as "core flush," 
is a physiological disease of certain varieties of apples. In the United States 
brown core occurs principally in New York and New England. The disorder is 
most serious on McIntosh, but Baldwin, Rhode Island, and Twenty Ounce may be 
affected. 
Smock (150) offered additional data to indicate that brown core is a 
low-temperature disorder and that susceptibility varies each year. He also 
found that limb shading greatly increased the disorder but that shading indivi- 
dual fruits or defoliating limbs had no effect. Nitrogenous fertilizers in 
some years increased brown core in storage. Smock (150) states that suscepti- 
bility to brown core in McIntosh apples is reduced by advanced maturity or by a 
delay in reaching cold storage. Padfield (122) also reduced brown core (core 
flush) in Granny Smith apples by a delay before refrigerated storage. He con- 
sidered the required delay too long to be practical, however. 
Smock and Blanpied (152) compared controlled atmosphere storage and film- 
box liners on the incidence of brown core in several varieties of apples. 
Neither controlled atmosphere storage at 38° F. nor the use of sealed film 
liners at the same temperature controlled brown core in Baldwin or Rhode Island 
Greening. Results on brown core in McIntosh were inconsistent in 1956 and 1957. 
(See also section on Controlled-Atmosphere Storage.) 
Phillips and Poapst (129) found that the seed physiology affected core 
flush (brown core) in McIntosh apples. For example, seeds that germinated in 
the shortest period following 6 months! storage were from fruits with the 
greatest amount of brown core. They conclude. that brown core could be reduced 
if seed activity could be controlled. 
Phillips, Poapst, and McQueen (130) reported that core flush (brown 
core) was reduced during 5 months' storage at 32° F. from an index of 105.3 to 
17.0 and superficial scald held to zero if McIntosh apples were exposed to 
85,000 rad of gamma radiation. 
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