Often through injudicious selection of varieties for original plantings,
or for some other reason, it becomes desirable to work over old trees to
more desirable varieties. This may be done by budding or grafting. In
either case the tree may be entirely reworked in one season or one-half
may be done the first season and the other half the next. The almond
will recover fully if completely deheaded to a height of from five to
six feet from the ground, provided it is not subjected to severe winds
or excessive moisture in the soil. Winds are liable to break off the
new top during the first year or two. Where these are dangerous it may
be well to leave half of the tree on the windward side to be worked the
second season. The remaining portions will help to serve as a wind-break
until the top-worked portion of the tree has a chance to unite solidly
with the stub of the main branch to which it is attached. Where winds
are not likely to do damage it is generally the most economical method
to work over the entire tree at one time. If the roots are subjected to
excessive moisture conditions during the first season, the new growth may
be unusually vigorous and much more likely to be blown out as a result of
the heavy top and the poor attachment to the stub. “Sour-sap” may also
be very serious. Under such conditions leaving half the tree the first
season will enable it to distribute the growth more evenly with less
undesirable forcing.
Whether the top-working shall be done by budding or grafting depends
largely upon the wishes of the grower and the skill of the workman.
Grafting will give a new tree more quickly than budding, because by the
latter method a year is lost in growing a supply of new wood on the stubs
into which the buds must be placed. By grafting, the new scions may start
growing the first spring without any delay. Ordinarily the best method
is to graft the trees the first winter and then, where the grafts fail
to grow, buds may be inserted in the new growth which will come from
the stub. During the first two seasons especially, great care must be
exercised to keep out the sprouts that interfere with the growth of the
scions. At the same time, all water-sprouts should not be removed during
the first summer or there will not be sufficient leaf surface to perform
the necessary functions of the tree. In addition, the scions tend to grow
so rankly that they will be top-heavy and much more liable to be blown
out by the wind, as shown in figure 6. This may largely be prevented by
pinching the ends of the new scion growth during the early summer to
force lateral branching. At the end of the first year all water-sprouts
should be removed leaving nothing but the growth from the scions.
[Illustration: Fig. 6.—Twenty-seven-year-old trees deheaded two years
before, showing the break-off of the new growth by strong winds.]