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1. Excessive or strong vegetative growth, 
especially in young trees just coming into 
bearing. Such trees usually set light 
crops and the fruits are abnormal in size. 
Fruits borne far out on the terminals 
are very liable to water core, whether 
the trees are old or young, providing the 
trees are vigorous. Trees making poor 
growth, which may be caused by soil 
conditions, lack of moisture, root trouble, 
or any other cause, rarely show water 
core in the fruit. 
2. High cultivation is a factor, but 
alone would not cause the trouble. How- 
ever, well cultivated soils retain moisture 
much better than those which are not 
cultivated, hence, as a rule, high cultiva- 
tion will promote vigorous growth and, 
therefore, favors water core, providing 
other factors are present. 
3. Excessive precipitation or irrigation 
shortly before the maturity of the fruit 
if followed by great extremes of temper- 
ature and atmospheric humidity, are fac- 
tors of the greatest importance. During 
hours of sunshine the moist ground is 
warmed to such an extent that water is 
readily taken up by the root system, and 
at this time transpiration is also very 
rapid. During the night the atmospheric 
temperature lowers to the point of satura- 
tion, this often being very little above the 
freezing point; however, the moist soil in 
which the roots are growing remains 
warm, or at least several degrees above 
that of the air temperature. Under such 
conditions, sap pressure is continuous, 
but transpiration is checked. Evapora- 
tion cannot take place from any surface 
when the surrounding medium (air, in 
this case) has reached the point of sat- 
uration. With transpiration checked and 
the sap pressure continuing, the tissues 
along the lines of greatest pressure 
must give way. These tissues are 
found in the fruits, especially those 
farthest out on the terminals, because 
they are exposed to extremes of temper- 
ature. Fruits on the south or southwest 
sides of trees are always most affected. 
4, Severe pruning shortly before the 
ripening period, or defoliation by disease 
or otherwise, thus causing the fruit to be 
exposed as well as reducing the evapora- 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
tion surface of the tree, will have a 
tendeney to produce water core. 
5. Frosts, which are severe enough to 
injure the foliage, have an effect similar 
to that of defoliation, since leaves which 
are so injured no longer function as true 
agents of transpiration. Certain chemi- 
cal activities are also set up in plants 
after frosts have injured them, and this 
produces rapid ripening in the case of 
apples. It is quite noticeable after a 
heavy frost that apples color rapidly, this 
being due to the formation and activity 
of certain enzymes. 
6. Cell tension or turgor may be in- 
duced by the rapid conversion of starch 
into sugar. This tension may be caused 
in two ways: (1) by the rapid absorp- 
tion of water by the sugar through os- 
motic pressure; (2) by the rearrange- 
ment of the molecules during the process 
of starch conversion into sugar. This, 
however, is of less importance than the 
other factors enumerated above. 
Weather conditions favored water core 
during the season of 1912 in the Rogue 
River district. During this period prac- 
tically clear weather prevailed. Begin- 
ning with August 31 and ending Septem- 
ber 8, 1.15 inches of rain fell. Following 
this period of moderate temperatures 
came three weeks of clear weather with 
high temperatures during the hours of 
sunshine and low temperatures during 
the nights. 
A careful examination of orchards of 
the same age and variety showed that 
the amount of water core present in the 
fruit was in direct proportion to the 
amount of precipitation or irrigation, 
range in temperature and range in rela- 
tive humidity. Records were taken on 
the valley floor where the range in both 
temperature and relative humidity was 
very great. At elevations where this 
range was not so great, there was very 
little water core. The amount of pre- 
cipitation also had its effect. In orchards 
where the precipitation was light, water 
core was much less abundant. A case 
was noted where the rainfall was sup- 
plemented by a heavy irrigation, both pre- 
ceding and after the rain occurred. In 
this orchard over 90 per cent of the fruit 
