PINCHING—BUD-NIPPING
“When the desired shape has been obtained the next thing is to keep it,
despite all opposition on the part of the tree, which revolts in its
own peculiar fashion; that is, it strives to restore the natural
conformation of its branches. Suppose, for example, that a pear-tree,
pruned after the manner of wall-fruit, has grown all out of symmetry
and developed one side more than the other. How shall the two halves be
restored to correct proportions? How shall the too vigorous part be
weakened and the too feeble part strengthened? Several methods offer
themselves.
“On the vigorous side let us cut back the branches with the pruning
shears, leaving only the base of each with a small number of buds; in
other words, let us cut them very short. On the weak side, on the
contrary, let us leave the branches intact or cut them very long, thus
leaving them the greater part of their buds. What will come of this
treatment? Since abundant foliage, the active laboratory of the
descending sap and also a kind of pump that sucks up the sap and causes
it to ascend from the roots, is the prime cause of vigorous vegetation,
the weak part, with its numerous buds developed into leafy shoots, will
grow stronger, while the strong part, with its small number of buds,
will become weaker. Both effects will tend to the same result: the
restoration of the desired symmetry.
“With the ends of the fingers and the help of the thumb-nail, it is
customary to pinch off from the too vigorous side the tips of the young
branches while they are still tender. This operation we may call
pinching. The sap that would have been used for the development of
these branches is diverted from its course and carried toward the weak
shoots, which it renews and stimulates. If the weak side itself needs
pinching to arrest shoots that impair the desired symmetry, the
operation is postponed as long as possible, while on the strong side it
is carried out very early. The sap thus turned away from the vigorous
side toward the ailing one has a whole season in which to restore the
lost equilibrium.
“Instead of limiting ourselves to pinching off the tips of the young
shoots with our thumb-nail, we can suppress them altogether while they
are still tender. This is done as early as possible on the strong side,
only the indispensable shoots being left. If it is necessary on the
weak side, it is not done until the latest possible moment. This
operation we may style bud-nipping, since the word ‘bud,’ by which we
designate the germ of the future branch when it is still enveloped in
scales, applies also for the sake of convenience to the branch already
developed but still young and tender. It is evident that nipping off
the buds from the strong part tends, even more than pinching, to
promote the desired growth of the weak part. The more branches we
suppress entirely, the fewer will be left to share the sap needed by
the branches we wish to strengthen.
“What turns aside the sap from the part pruned, pinched, or nipped,
toward the part left intact, is evidently the more or less complete
suppression of foliage. It is primarily the leaves that by the
continual evaporation of which their surface is the seat determine the
ascent of the liquid drawn from the soil by the roots. The more
numerous these leaves are at any one point, the more abundant the flow
of sap to that point; the scarcer they are, the less the flow of sap.
To diminish at any point the number of leaves by pinching, bud-nipping,
or any other means, is therefore to diminish at the same point the flow
of sap, which will go in some other direction, to the parts that have
more leaves and hence a more rapid rate of evaporation to summon the
sap. It is plain, then, that a middle course may be followed between
the pinching that partly suppresses the foliage of a young branch and
the bud-nipping that suppresses it entirely. This middle course
consists in cutting a certain number of leaves from the too vigorous
shoots; and they should be cut clean without tearing, by severing the
stem and leaving its base undisturbed.
“The easiest way for the sap to run from the roots to the foliage is
from bottom to top in a vertical line. Anything that interferes with
this course hinders also the upward impetus. Thus in branches with
sharp elbows and abrupt bends the rush of sap is slackened just as the
rate of flow of a water-current is diminished by the windings occurring
in its bed. Thus, again, in a branch having a decided incline downward
the sap moves with difficulty, because its movement toward the
extremity of this branch is in a direction contrary to that which is
natural to it. The application of this principle is evident. If we wish
to moderate a too vigorous growth of branches, we bend them toward the
ground; if we wish to stimulate a too feeble growth, we straighten up
the branches until they assume a vertical posture.
“We can also turn to account the exhausting effect of fruit-bearing.
The more fruitful a branch is, the weaker it becomes, since the use of
sap in fruit means so much the less for foliage, and it is foliage that
invigorates the branch. Accordingly we will leave the greatest possible
quantity of fruit on the strong part of our tree, and suppress it on
the weak part.”