of growing
grapes in this great region.

Through the use of resistant stocks, phylloxera is now defied in
Vinifera regions. Millions of American stocks are annually struck at
home, in Europe and wherever Vinifera grapes are grown, to be
top-worked with varieties susceptible to phylloxera. Seldom has
mastery over a pest been so complete; but, to triumph over the tiny
insect, the industry has had to be revolutionized. Resistant stocks,
in their turn, brought innumerable new problems, many of which are
still unsolved. Investigations and experiences in rehabilitating
vineyards have been carried on for forty years, the results set forth
in books and bulletins and yet there are many problems to be solved.
The grape-grower in regions infested with phylloxera is always under
the necessity of taking advantage of the latest demonstration of
practices in the use of resistant stocks. These practices are best
studied in the experiments of state experiment stations and the United
States Department of Agriculture, and in the vineyards of leading
grape-growers, since even those most needing elucidation can be but
briefly discussed in the following paragraphs.

The wild vines of a species are always seedlings and are hence
exceedingly variable. The first vineyards of resistant stocks were
vines grafted on stocks of wild vines, and the results were very
unsatisfactory; for, naturally, there was divergence in many
characters and especially in the vigor of the vines. Also, there was
difficulty in grafting, since some wild vines are stout and others
slender; some bear grafts well, while others do not. It soon became
apparent that to succeed, varieties must be selected from the
different species for vineyard work. The great task of the
experimenter and grape-grower, therefore, has been to select varieties
of the several species sufficiently resistant, vigorous and otherwise
possessed of characters fitting them to become good stocks. Out of
vast numbers tested, a few are now generally recognized as best for
the several groups of Vinifera grapes and the several distinct regions
in which these grapes are grown.

_Resistant species and varieties._

The reconstruction of phylloxera-ridden vineyards by the use of
resistant stocks is possible only because some species and varieties
are, as has been said, more resistant to the root-louse than others.
All degrees of resistance exist, as would be suspected, from immunity
to great susceptibility