MAKING FRUIT TREES BEAR
“If one side of a tree is pruned very short and the other very long,
the natural course of the sap is to some extent diverted from the first
side toward the second, which is richer in buds and consequently in
foliage. We have just seen how this principle is utilized to check the
growth of too vigorous a part in order to stimulate that of one that is
too feeble and thus redress the balance between the two. But what would
be the result if the whole tree were pruned at once?
“Let us first see what takes place in a single branch. Pruned long, it
preserves the greater part of its buds, all of which call for
nourishment from the sap flowing in that direction; pruned short, it
keeps only a few buds, which having the sap of the entire branch at
their disposal, will receive each a supply that is superabundant in
proportion to the fewness of the buds. For example, what twelve would
ordinarily have had for consumption, two or three will now have to
themselves; and because of this superabundance of nourishment each bud
will develop much more vigorously than it would otherwise have done.
Hence if the whole tree is pruned with an unsparing hand, all the sap
drawn from the soil by the roots, having no longer a tendency to go to
one side rather than the other, will be distributed evenly; and the few
buds left intact by the pruning-shears will show a luxuriance of growth
in proportion to the supply of nourishment placed at their disposal.
Thus thorough pruning applied to the whole tree has the effect of
giving it new vigor, of rejuvenating it in some measure, or, in other
words, of replacing its worn-out branches with vigorous ones.
Accordingly when a tree has become exhausted by abundant fruit-bearing,
it is pruned without stint one year in order to restore its vigor of
growth.
“Let us now see what we should do if we had quite the opposite end in
view; that is, if we wished to make a tree blossom and bear fruit. Here
two principles will serve us as guides. First, in the fulness of its
vigor a tree puts forth long branches and thick foliage, but does not
cover itself with blossoms, bearing in fact only a few. It is not until
it has become somewhat enfeebled that it begins to flower in profusion.
Secondly, what would in the tree’s youthful strength have been a
branch-producing bud becomes in its enfeeblement a flower-bud; so that
a flower may be regarded as a branch which, instead of developing
freely and covering itself with leaves, has remained stunted, thrown
back upon itself, for lack of vigor, and has exchanged its leaves for
floral organs,—sepals, petals, stamens, pistils. Weaken a tree and you
weaken the buds; such, in a word, is the prevailing principle.
“To weaken the buds individually, the pruning-shears will be plied but
sparingly, leaving the buds almost intact; then these, being many in
number, will have so much the less for each one separately, and some of
them, especially toward the lower part of the branch, will find
themselves too feeble to contend with the others and therefore will
take the form of flower-buds, whereas they would have produced branches
and not flowers if a more thorough pruning had rid them of their
rivals.
“To weaken the tree as a whole, all that we have to do is to pinch off
or cut off with the thumb-nail the tender tips of the young branches;
then we bend these branches back so as to give them a number of crooks
and turns that will impede the circulation of the sap. Finally, the
woody branches of the preceding year are broken by the hand, sometimes
wholly, sometimes half, so that the tip is left hanging down. If the
tree is not too vigorous these three methods, pinching, bending, and
breaking, are generally sufficient to make it bear.
“But when we have to do with very exuberant vegetation, more energetic
methods are necessary. One of these we may call arching. The branches
are all bent down so that each forms an arch; that is, the tip-end of
each is pulled down to the ground and fastened there in any way that
may be easiest. This abnormal position of the branch, with its top
downward, is contrary to the ascending movement of the sap, which
consequently flows less freely to the buds. The resulting dearth is
conducive to fruit-bearing, and as soon as this effect is assured the
branches are allowed to return to their natural position; otherwise the
tree would become exhausted.
“Another method is as follows. Pruning is done very late, when the
young shoots are already some centimeters long. The sap used up in the
growth of the shoots cut off by the pruning shears is a great loss to
the tree, which, being no longer able to supply ample nourishment to
the lower buds of the branches, turns them into flower-buds.
“If these means do not suffice to make the tree bear fruit, there are
more violent ones which are employed only in the last extremity. Toward
the end of winter, before the sap has started, an incision some
millimeters wide and deep enough to penetrate the outer layers of wood
is made all around the base of the trunk. Sap, as we know, ascends
through these exterior layers, the newest, the most permeable by
liquids; so if we partially intercept its passage it will flow less
abundantly to the buds and the weakened tree will soon begin to bear.
“Still another expedient is to strike at the very source of the sap,
the roots. The foot of the tree is laid bare in the springtime, its
main roots being denuded of their covering and left thus exposed all
summer to the open air and the hot sun. No longer enjoying the coolness
and darkness necessary to their office, they furnish less nourishment
to the tree, and this scarcity causes the formation of flower-buds. A
still more drastic method, but one that would kill the tree if employed
imprudently, is to strip the roots of the refractory subject without
mercy, cutting and mutilating a certain number of them and then putting
back the earth that has been removed. A diminution in the flow of sap
must necessarily result from this surgical operation. Finally, if the
tree is small enough for the purpose, it is dug up at the end of
autumn, with care to preserve the roots as far as possible, and planted
again somewhere else. The disturbance caused by this change of place
suffices to make the tree blossom the next year.”