4 BULLETIN 1448, U. S. DEPARTMENT OF AGRICULTURE 



SOFTENING OF THE FRUIT 



Another change which in many varieties, and particularly under 

 certain growing conditions, affords a good index to the picking con- 

 dition of the fruit is the softening of the flesh of the apple. Soften- 

 ing is the outstanding change in apples as they ripen in storage. 

 Also, there is usually a distinct softening as the fruit approaches 

 maturity on the tree, though the apple may be so firm at this time 

 that the condition is not readily apparent unless measured mechan- 

 ically. Although the rate of softening of apples attached to the 

 tree is relatively slow, the measurement of the firmness of the flesh 

 is of much value, particularly in determining when certain varieties 

 are becoming so ripe that their storage quality is being impaired. 



LOOSENING OF FRUIT ON THE TREE 



Another very useful method for determining when fruit is ready 

 to remove from the tree is based on the manner in which the fruit 

 adheres to the tree. Most varieties of apples as they approach proper 

 picking condition tend to loosen from the spur, so that when the 

 fruit is lifted the stem readily separates. This test, which is very 

 generally used for determining the time for picking apples, is very 

 valuable for many varieties, but with certain varieties and under 

 certain conditions is much less satisfactory. 



THREE MAIN FACTORS 



After a careful study of all the changes which occur in apples as 

 they approach picking maturity, it thus appears that the three 

 factors of greatest value in determining when to pick the fruit are 

 (1) the degree of yellowing in the unblushed or unco lo red portion 

 of the fruit, (2) the firmness of the flesh of the fruit, and (3) the 

 way the fruit is holding on to the tree or the ease with which it may 

 be picked. The relative value of these different tests will vary with 

 different varieties and with the same variety grown in different 

 parts of the country. 



METHODS FOR DETERMINING CHANGES INDICATING PROPER 

 TIME FOR PICKING 



For determining the rate of yellowing in the uncolored portions 

 of apples the color chart reproduced in Plate 1 has been used. These 

 colors closely approximate the color stages through which apples pass 

 as they ripen on the tree and in this form may prove of value to 

 apple growers in following the changes in the ground color of differ- 

 ent varieties from season to season. A circular hole about three- 

 fourths of an inch in diameter should be cut in the center of each 

 of the four colors on the chart with which it is desired to compare 

 the color of the fruit. The fruit should be placed back of the chart 

 and the unblushed portion fitted into the holes cut in the different 

 colors. By this means it is possible to obtain the same light exposure 

 on the fruit and on the color chart, and they can thus be accurately 

 compared. The best matching of color is obtained by making the 

 comparison in daylight in the shade. Direct sunlight or artificial 

 light appears to make a slight difference in the comparative values 



