nd by pruning. Pruning is used to decrease the vigor of the
vine, in theory at least, for the practice is not always so
successful, by pruning the roots or by summer-pruning the shoots.

Root-pruning the grape at intervals of several years is a regular
practice with some varieties in warm countries, Europe more
especially, but is seldom or never practiced in America except when
planting and when roots arise from the cion above the union of stock
and cion.

Summer-pruning to induce fruitfulness consists in removing new shoots
with newly developed leaves. These young shoots have been developed
from reserve material stored up the preceding season, and until they
are so far developed that they can perform the functions of leaves
they are to be counted as parasites. When, therefore, these shoots are
pruned or pinched away, the plant is robbed of the material used by
the lusty shoot which up to this time has given nothing in return. The
vigor of the plant is thus checked and fruitfulness increased.
Summer-pruning may become harmful if delayed too long. The time to
prune is past with the grape when the leaves have passed from the
light green color of new growth to the dark green of mature leaves.

Fruit-bearing may be augmented by bending, twisting or ringing the
canes, since all of these operations diminish vegetative vigor.
Ringing is the only one of these methods in general use, and this only
for some special variety or special purpose, and usually with the
result that the vigor of the vine is diminished too much for the good
of the plant. Ringing is discussed more fully in Chapter XVI.

_The manner of fruit-bearing in the grape._

Before attempting to prune, the pruner must understand precisely how
the grape bears its crop. The fruit is borne near the base of the
shoots of the current season, and the shoots are borne on the wood of
the previous year's growth coming from a dormant bud. Here is
manifested one of Nature's energy-saving devices, shoot, leaves,
flowers and fruit spring in a short season from a single bud. In the
light of this fact, pruning should be looked on as a simple problem to
be solved mathematically and not as a puzzle to be untangled, as so
many regard it. For an example, a problem in pruning is here stated
and solved.

A thrifty grape-vine should yield, let us say, fifteen pounds of
grapes, a fair average for the mainstay varieties. Each bunch will
weigh from a quarter to a half pound. To produc