important that means be devised for determining the beginning and 
duration of this period, so that apples may be picked during this 
period as far as practicable. 
Many factors determine the best time to harvest an apple crop. 
Each variety presents an individual problem. The importance of the 
factors involved in establishing indexes of maturity will depend on the 
variety but may vary within a variety, with different cultural and 
climatic conditions. In the case of all varieties, however, the fruit 
increases in size as long as it remains attached to the tree. 
From this standpoint it is desirable to leave the fruit on the tree 
as long as dropping does not equal or exceed the volume increase. 
However, picking should be completed by the time the loss due to 
dropping equals the gain due to volume increase. Since the time when 
dropping is likely to become excessive cannot be predicted, picking 
should start while the fruit is still adhering well. 
It has been suggested that the time at which apples should be picked 
may be determined by the ease with which fruit can be separated from 
the spurs and the extent to which sound fruit is dropping. However, 
under certain conditions the apples may start to drop before satis- 
factory maturity from the standpoint of dessert and storage qualities 
has been reached. As indicated, the tendency to drop is not a satis- 
factory index of when to start picking; for once dropping has started 
it is likely to become excessive before picking can be completed and 
the change in ease of separation of the fruit from the spurs previous 
to dropping is not sufficiently marked or distinct to be taken as a pick- 
ing guide. 
The amount of red color on red varieties, which increases during the 
harvest period, is an important factor in the commercial value of the 
erap, It “1s desirable to leave the apples on the tree until sufficient 
red has developed. However, with some varieties and conditions the 
fruit may become overmature before it becomes well colored. On the 
other hand, apples of some of the red bud sports may become well 
colored while still immature. 
The change in the ground color from green to yellow is desirable, 
particularly: with yellow varieties such as Golden Delicious and Grimes 
Golden. This change has also been suggested as an index of picking 
maturity. With many varieties there is no appreciable change in the 
green color at the approach of maturity, and with others the changes 
are not sufficiently marked or consistent to be of much value. 
There is a gradual softening of the fruit on the tree previous to and 
during the harvest period. This change is useful as an indication that 
the fruit is becoming too soft for ood : storage quality. 
Changes in horticultural practice and recent investigations * have 
shown the need for some changes in the recommendations made in 
2In a cooperative iny estigation between the Bureau of Plant Industry, Soils, and Agri- 
cultural Engineering and various State agricultural experiment stations, data relative to 
the elapsed time from bloom to maturity have been obtained in different apple-producing 
districts as follows: For Virginia, Maryland, and West Virginia by Mark H. Haller, Bureau 
of Plant Industry, Soils, and Agricultural Engineer ing: for W ashington by Edwin Smith, 
Bureau of Plant Industry, Soils, and Agricultural Engineering ; for Illinois by Richard 
V. Lott, Ilinois Agricultural Experiment Station ; EGE Ohio by C. W. Ellenwood, Ohio 
Agricultural Experiment Station; for Michigan by Roy I 2. Marshall, Michigan Agricultural 
Experiment Station ; for New York by Henry O. Bennett, Bureau of Plant Industry, Soils. 
and Agricultural Engineering ; and for Oregon by Gordon Brown, Oregon Agr icultural 
Experiment Station. A preliminary report (8) has been made of some of the data for 
Virginia, West Virginia, and Maryland. The more recent data have not been published but 
have been used as a basis for making recommendations relative to the number of days from 
bloom to maturity in this circular. Such recommendations are based on the results of 
these cooperative studies except when other references are cited. 
2 
