FRUITS—SETTING AND DROPPING 
formation of fruit buds. One of the gen- 
eral aims of pruning is to regulate the 
crop of fruit by removing parts of the 
plant that those remaining may store the 
necessary food. The theory of pruning 
to cause formation of fruit buds is sim- 
ple but the practice is not so simple. The 
effects of pruning are so varied under dif- 
ferent conditions that it is exceedingly 
aifficult to give directions as to its use 
in influencing the setting of buds. 
Heading-in may sometimes be used to 
advantage in pruning for fruit. It con- 
sists in cutting back young, unbranching 
shoots which set few or no fruit buds 
Heading-in is a necessity with dwarf 
trees. Practice differs as to whether the 
operation should be performed in sum- 
mer or winter but it is usually performed 
in summer and is then spoken of as sum- 
mer pruning. Heading-in greatly thick- 
ens the top, thereby excluding light, and 
must be practiced very judiciously or 
more harm than good is done. 
Summer Pruning 
Summer pruning is rather commonly 
used to influence the formation of fruit 
buds for the succeeding season. The 
theory is that by removing a part of the 
young shoots of the current season, we 
take from the trees the portions which 
are making the greatest demands on the 
plant’s nutritive powers and that the re- 
maining parts of the shoots with their 
buds are enabled to store up greater 
quantities of reserve food than they oth- 
erwise could. This summer heading-in 
should be done before growth ceases. So 
much, however, depends upon several 
varying factors that no fixed rule can be 
given as to time; thus, much depends 
upon the fruit, the varieties, soil, climate, 
weather and the amount of growth. 
Summer pruning is a weakening pro- 
cess and may permanently injure a tree 
in our climate. With standard trees it 
is only of advantage in moderation in 
eastern North America and as usually 
practiced more often results in evil than 
in good. Summer pruning is of more 
value in the early life of the tree than 
later on. Summer pruning as means of 
inducing fruitfulness is greatly overesti- 
1061 
mated under American conditions and be- 
longs more properly to the elaborate sys- 
tems of pruning and training practiced 
by Huropeans. 
Ringing 
Those who do not find pruning a suf- 
ficiently drastic method of checking wood 
growth to augment fruitfulness may re- 
sort to the removal of a ring of bark 
from the trunk of the tree. In rather ex- 
tensive experience on the grounds of this 
station, we have found ringing of some 
use with the apple. Our practice is to 
remove a ring of bark from one-half to 
one inch wide from young apple trees at 
the period when the trees are making 
the greatest growth, usually about the 
middle of June. If the ringing is done 
earlier in the season or later in the sea- 
son than June, injury is certain to re- 
sult. Should it be done when the growth 
is being checked by drought, injury 
would also result. 
The theory upon which ringing is 
based is simple. Crude sap passes from 
the roots to the leaves through the out- 
er layer of wood. In the leaves this crude 
material is acted upon by various 
agencies and transformed into food sub- 
stances. This accumulated material 
passes downward through the inner bark 
to be distributed throughout the plant 
where needed. When trees are ringed the 
flow of sap upward through the wood con- 
tinues as before the operation, but the 
newly made food-substance can not pass 
below the girdle and, therefore, accumu- 
lates above and is used for the formation 
of fruit buds, though at the expense of 
other parts of the plant. 
Heredity 
Is heredity a factor in bud formation? 
Can the fruit-bearing habit be passed 
down from one tree generation to an- 
other? Can the habit be augmented and 
intensified by selection? Individuals in 
an orchard vary as to time of coming in- 
to bearing, regularity of bearing and num- 
ber of buds formed in any season. But 
it has not been proved that buds chosen 
from the trees best in these respects 
would produce trees that are early bear- 
ers, or more regular in bearing or more 
