illustrates the method of making the test. The fruit to be tested may 
be placed against any convenient solid surface, such as a wall or the 
trunk of a tree, if the test is being made in an orchard. The plunger 
tip is placed in contact with the cut surface and pressure is applied. 
When the plunger tip has penetrated to a depth of five-sixteenths 
of an inch, as shown by a line on the plunger tip, the pressure in 
pounds required to force the plunger into the fruit to this depth is 
read directly on the scale. In order to obtain a satisfactory indica- 
tion of the condition of any variety, at least 10 to 20 apples selected 
from different trees and different parts of the trees should be used. 
Two or more tests may be madé on each apple and the results 
averaged. Tests should be made within a few hours after picking. 
Values reported herein as firmness ranges for different varieties are 
based on tests made as described with the peel removed prior to test- 
ing. The application of pressure-test determinations to maturity 
and ripeness of fruits has been discussed in a recent publication (7). 
LOOSENING OF FRUIT FROM SPURS 
As apples approach proper picking condition they generally tend to 
loosen from the spur so that when the fruit is hfted the stem readily 
separates. However, under certain growing conditions the fruits of 
some varieties such as McIntosh and Delicious may loosen and release 
easily before they reach satisfactory maturity. Early frosts also may 
cause fruit to loosen and drop before it is mature. On the other hand, 
fruits of certain varieties such as Jonathan and Stayman Winesap may 
adhere tightly until the fruit becomes overmature. Ease of separation 
of fruit from spurs, therefore, is not necessarily an indication of proper 
maturity, but 1t may indicate when picking is necessary to save the 
crop. In recent years harvest sprays of certain growth-modifying 
chemicals such as «-naphthaleneacetic acid (7) have been used exten- 
sively for the prevention of fruit dropping, making unnecessary the 
premature picking of fruit that shows a tendency to drop early. 
The ease with which fruit may be loosened from the spurs has 
become even less reliable as an index of picking maturity since the 
adoption of sprays for the control of harvest drop. The use of these 
sprays has made the maturity problem more complex because after 
their use fruit may be permitted to remain unharvested until it becomes 
overmature. 
The tenacity with which the fruit adheres to the tree can be esti- 
mated only in a general way. If the stem of a sound fruit separates 
from the spur when the fruit is lifted or is given a slight twist, it would 
be considered that the fruit is loosening on the tree and separates eas- 
ily. Under this condition it is probable that a small amount of sound 
fruit may be dropping. If no fruit is dropping and if the fruit can 
be picked only with considerable effort, it is considered that the fruit 
is still firmly attached to the tree. The dropping of wormy or other- 
wise injured fruit is not an indication of picking maturity. 
DEVELOPMENT OF WATER CORE 
The development of water core in the fruit is a very important con- 
sideration in determining when to pick certain varieties. Investiga- 
tions by Brooks and Fisher (2) have shown that water core usually 
8 
