d is to be planted. The several species
used for stocks differ widely in the requirements affecting growth so
that the grower must make certain that the resistant stock he selects
will find congenial surroundings. Stocks in congenial circumstances
are frequently more resistant than others inherently more resistant,
but which are not otherwise adapted to the particular conditions of
the vineyard. Species of grapes vary greatly in their root systems,
some having thick, others slender roots; the roots of some are soft,
of others hard; some have roots going down deeply, others are almost
at the surface of the ground. Manifestly these various root-forms are
but adaptations to loose and heavy, dry and moist, deep and shallow
soils, or to some circumstance of climate. A vine bruised by adversity
is in no condition to withstand phylloxera. Therefore, since the
adaptability of a variety to a soil or climate may be changed by the
stock, the adaptations of stocks to soils and climates must have
attention.

_Affinity of stock and cion._

Different varieties of grapes do not behave alike on the same stocks,
and different stocks may affect varieties differently. Even when the
kinship is close, some grapes resist all the appliances of art to make
a successful union; while, on the other hand, quite distinct species
often seem foreordained to be joined. For example, Rotundifolia, which
has the highest resistance to phylloxera of any species, is useless as
a stock because it is impossible to graft any other grape on it, while
Vulpina and Rupestris unite readily with varieties of Vinifera, the
slight decrease in the vigor of the grafted vines serving oftentimes
to increase fruitfulness. Something more is necessary, then, than
botanical kinship. Just what is necessary, no one knows, beyond: that
there must be conformity in habit between stock and cion; that the two
must start in growth at approximately the same time; and that the
tissues must be sufficiently alike that there be proper contact in the
union. Yet these facts do not sufficiently explain all of the
affinities and antipathies which species and varieties of grapes show
to each other. Unfortunately, the grape-grower has had but little to
guide him in selecting stocks and has had to learn by making repeated
trials.

PROPER PLANTING OF GRAFTED VINES

Europeans and Californians long ago learned that failures with grafted
vines often came from setting the vines too deep in the