Aug. 1, 1924 
Freezing Injury of Apples 
103 
paintings made from cross sections of a 
Delicious and a Winesap apple, which 
are representatives of this type of 
injury. In Winesap apples, particu¬ 
larly where the secondary fibro-vascu- 
lar system seems to have a consider¬ 
able development just beneath the 
skin, a well-defined net necrosis may 
often be observed when the skin is 
peeled off without cutting too deeply 
into the flesh. Lens examination of 
thin sections of such apple tissue shows 
the apple cells generally clear and trans¬ 
lucent, and the discoloration in varying 
tones of brown affecting only the cells 
of the bundles or those cells imme¬ 
diately adjacent. This fact applies 
equally to the primary bundles usually 
seen as large dots in concentric circles 
around the carpels, and to the secondary 
bundles scattered through the tissue; 
but both types of bundles do not neces¬ 
sarily show discoloration in the same 
apple. This may also be said of dis¬ 
coloration of the cambium, which 
appears as an entire concentric ring 
about the carpels and at times seems 
to join the primary fibro-vascular bun¬ 
dles, as shown in Plate 2, A. Dis¬ 
coloration of all of these may appear 
in the same apple; in other specimens 
discolorations may appear alone or in 
connection with other types of injury. 
Discoloration of other interior tissue 
than the bundles or cambium fre¬ 
quently is found. For some varieties 
it is evidence that the degree of freezing 
has been more severe than that pro- 
duping the injury described above. 
For others it is the characteristic re¬ 
action to any temperature sufficient to 
produce injury, and here vascular or 
cambial discoloration may be masked 
or entirely absent (Pis. 2, B; 3, A and 
B). This general discoloration of the 
tissue exhibits all degrees of intensity 
and when most pronounced marks the 
severely frozen apple. In some apples, 
there is in addition a marked softening 
and a mushy watery appearance; in 
others the flesh of the apple seems dry 
and mealy. The tissue resembles that 
in a state of decay and is wholly dis¬ 
colored, generally in tones of brown, not 
uncommonly with yellow or green hues. 
Sometimes quite brilliant blotches of 
color occur; or clearly defined lighter 
colored lines radiate from the center; 
and the cambial region may stand out 
as a deeply colored area. 
Visual freezing injury occurring 
on the surface of apples. —Surface 
injury other than that due to bruising 
while frozen consists of discoloration of 
the surface layers of cells and is usually 
quite shallow. One of the two usual 
forms consists of a brown skin discolor¬ 
ation with poorly defined edges re¬ 
sembling a bruise except for a certain 
water-soaked appearance (PI. 4, A). 
This injury is sometimes mistaken for 
soft scald, but is quite different, be¬ 
cause the lesions of soft scald are 
definite in outline, dull in color, and 
somewhat sunken in a late stage. The 
other common form of surface injury 
occurs only on red apples or on the 
blushed side of the fruit. (See PI. 4, B.) 
It is a yellowish-brown discoloration 
resembling in some cases the work of 
leaf-miner larvae in leaves. More 
often it appears as small discolored 
areas, very irregular in outline but 
rather clearly defined. In storage these 
areas may remain quite intact, or they 
may become more or less sunken, en¬ 
larged, and of a dark brown color. 
This enlargement seems caused by 
death and discoloration of cells adja¬ 
cent to those showing injury very soon 
after freezing has taken place. In 
many Winesap apples the tissue imme¬ 
diately beneath such places had dried 
completely after a storage period of 
three months, and had been replaced 
by cavities sometimes 10 mm. in depth, 
lined with brown corky tissue com¬ 
posed of dead cells. To some degree 
these cavities resemble the drought 
cracks occasionally found in apples like 
the York Imperial, and probably are 
caused by an increased water loss from 
the frozen tissues. 
Since the intercellular spaces have 
intimate connection with the lenticels 
or corky openings in the skin, the loss 
of water vapor is augmented above the 
ordinary amount. The greater tend¬ 
ency to wilting and to rapid water loss 
is characteristic of frozen apples thawed 
under conditions favoring the removal 
of moisture from the fruit. Apples 
frozen to a certain degree may also 
have a water-soaked appearance, and 
a skin tough and resilient to the touch. 
As a general rule, surface discoloration 
due only to freezing is very shallow. In 
varieties with a green color, notably the 
Yellow Newtown, it often occurs before 
other visual freezing injury can be de- 
EXPLANATORY LEGEND FOR PLATE 2 
A. —Cross section of Grimes apple, grown in Virginia, showing discoloration of the carpel and cambial 
regions, and of the primary fibro-vascular bundles. A rather severely frozen specimen. 
B. —Cross section of Ben Davis apple, grown in Virginia, showing discoloration of the central portion of 
the fruit. The brown areas near the periphery are probably bruises made while the fruit was in a hard 
frozen condition. A rather severely frozen specimen. 
