e expensive to use.

Chapter 18

EFFECTS OF GRAFTING ON UNLIKE STOCKS

It is unquestionably a great shock to a tree when 90% of its top is cut
off. If it is healthy and vigorous, the root system will try to recover,
using every means possible to do so. If a new top is grafted to it, the
stock must either accept and nourish that foreign and sometimes
incompatible new part, or give up its struggle for life. Nature and the
tree stock usually accept the challenge and the graft begins to grow. In
an attempt to continue with its own identity, the stock will bring into
activity adventitious buds. These are tiny microscopic buds imbedded in
the bark of a tree that are not apparent to the eye but are nature's
protection against destruction of the individual plant. But these must
be removed by the horticulturist to insure proper nourishment of the
grafts.

Because the root system is striving hard to live, and because it is
usually the stronger, it may force the top to accept certain of its
characteristics. Occasionally, it may assume some qualities of the
original top. Such cooperation is necessary if either is to survive.
First of all, the grafted scions must accept the vital quality of
climatic hardiness, a powerful factor developed through ages spent in a
certain climate. To hasten the acclimatization of a tender variety, I
cut scionwood from such unions early in the winter, storing it until
spring. When these scions are grafted on new root systems, I find that
they are much more readily accepted than the first grafts were. The
following season, I allow the grafts of this later union to go through
their first winter of exposure. Early each spring I continue to cut
scions from the most recent unions and graft them to new root systems,
so hastening and setting the factor of hardiness through frequent
asexual propagation.

Because my observations of the effects of scion on root and vice versa,
have not extended over a sufficient period of time, I think it is
possible that the changes I have seen may be only transient. In any
case, I do know that the phenomenon occurs, for I have seen many
examples of it.

One instance in which the stock was apparently affecting the scions,
occurred in the case of several varieties of black walnuts which had
been grafted on wild butternut stock over a period of sixteen years. The
walnut top flourished but tended to outgrow the butternut, so that the
caliber of the walnut was greate