THINNING AS AN AID— 
TO APPLE PROFITS 
By Ray Klackle 
The thinning of apples to improve 
their size, color and quality is a 
practice which has been followed by 
fruit growers for a good many cen- 
turies. Writings of ancient and 
medieval authorities comment on the 
method. Just how much actual in- 
come is gained by the practice has 
not yet been definitely proved, but 
experiments carried on by the U. S. 
Department of Agriculture and 
various state Agricultural Experiment 
Stations are being followed closely in 
an effort to arrive at definite con- 
clusions. 
That the advantage of thinning 
varies with different varieties has 
been fairly conclusively proved. This 
applies both to apples and peaches. 
In this article we will review some of 
the studies made in connection with 
apples. A similar article on peach 
thinning will follow. 
Thinning should follow intelligent 
pruning. In Bulletin No. 1360 of the 
U.S. Dept. of Agriculture, it is pointed 
out that during the period from plant- 
ing to bearing age, pruning is de- 
signed to make the tree strong of 
limb and compact in form, by cutting 
back certain branches and thinning 
out the top by removal of others. 
As bearing starts, this practice con- 
tinues, with special relation to the 
development of fruit buds and fruit. 
“The pruner should keep constantly 
in mind,”’ the Bulletin continues, ‘‘that 
neither fruit spurs, fruit buds, nor 
the fruit itself develop well in dense 
shade. Therefore the top should be 
kept sufficiently open to admit sun- 
light to the bearing areas.’’ This 
method also distributes the weight of 
the crop throughout the tree, where 
it can be borne with least danger of 
breaking branches. 
Under favorable conditions apple 
trees are likely to set a larger crop 
than can be matured to the size and 
12 
perfection which are most easily 
marketable. One reason for this is 
that the development of SEEDS takes 
more from the vitality of the tree than 
the development of pulp. So that a 
lot of small apples will take more from 
a tree than fewer large ones, besides 
giving the grower a less valuable 
crop. 
Thinning has other advantages. It 
may be done when bearing is heavy, 
to prevent breakage of limbs. Thin- 
ning reduces activity of codling moth, 
whose larvae work seriously on fruits 
in contact with one another. 
The thinning is usually done, at 
least on late varieties, just after the 
“June drop’; this ‘June drop” of 
course, is not always in June, usually 
occurring about four to six weeks 
after blossoming. 
Experiments have so far proven 
that hand thinning is more practical 
than use of the shears. By grasping 
the stem between the thumb and fore- 
finger, the next two fingers may grasp 
the apple and pull it off. This pre- 
vents pulling off clusters or spurs. 
The apple may be dropped through 
an open space in the tree or out to 
the side, thus avoiding bruising other 
fruit below. It may be desirable to 
use adhesive tape on the fingers until 
they become hardened to this work. 
In Bulletin 508 of the Ohio Ex- 
periment Station, which gives a 
thorough survey of the subject of 
Apple Thinning with special Refer- 
ence to Grimes and Jonathan, it is 
pointed out that the use of shears 
has slowed up the work of thinning 
considerably. 
In thinning, authorities agree that 
it should be the aim to remove im- 
perfect or insect-marred fruit, and 
small or knotty apples on lower inside 
limbs which seldom become market- 
able. 
For thinning trees more than 12 
