Macadamia Nuts in Hawaii: History and Production - ctahr ...

Figure 55. Root system of a tree propagated and grafted early in a
deep poly pot (center) showing a developing taproot.
The trees to the left and right were propagated in shallow
poly pots and have many roots congested in a nacro\v
section.
containers with one tha t was propagated in a long,
narrow tube. Using these narrower tubes and
grafting as early as possible by using smaller scion
woods are ideas that merit more thought.
The use of this sytem should produce fieldplantable
trees 15 to 18 months after seed placement
in containers. In addition to Rancho
Nuez Nursery in California, one nurseryman in
Hilo is successfully propagating grafted trees in
this manner (Fig. 55).
The seedling propagation scheme suggested
here is very different from the methods now
employed and is based on evidence gathered by the
authors in the last 20 years. It is offered here as an
alternative to a system that needs improvement.
Preparation for grafting. Macadamia seedlings
can be grafted at any time of year, provided that
the seedlings are actively growing. Fertilizer
applied a month or two before grafting will better
insure cambial activity. The scion wood should
also be specially prepared to induce long, caney
growth (Fig. 56). If this is not possible, succulent
growth emerging when trees are pruned, or succulent
growth from young trees, is adequate. However,
straight succulent sprouts extending vertically
on a pruned tree do not make good scion
wood since they do not seem to store starch when
girdled. These selected limbs should be girdled six
to eight weeks prior to grafting to accumulate
starch above the girdle (Fig. 22). Girdling is easily
done by gripping the stem, using pliers to damage
the bark through to the wood to stop the flow of
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starch past the girdle. The girdle needs to be only
about)1 inch (1 centimeter) wide. Thegirdled stem
should be tested for starch before use. This can
best be done by snipping the very small terminal
of girdled stem and immersing the cut portion in a
solution of iodine and potassium iodide. Diluted
tincture of iodine from any drugstore can be substituted.
Starch deposition, as shown in Fig. 22,
indicates that the stem is ready to be used.
Grafting. Macadamia seedlings can be grafted
by any of several methods. Moltzau initially used
the veneer method with success (Fig. 46). A deep
side-wedge, with the seedling stem bent over to
permit the scion wood an upright orientation, is
now practiced exclusively in Kona. A drawback in
wedge grafting is that when the wedge is not cut
deeply, the scion wood sometimes slips and separates
before the union is completed.
When the graft takes hold and the initial vegetative
growth of the scion wood hardens, a vigorous,
central upright sprout should be selected and the
other sprouts eliminated. The seedling stem at the
graft union can then be cut off as close to the scion
wood as possible. Pruning paint should be dabbed
on the cut surface to prevent decay a t the graft
union. The trees will be ready for field transplant
eight to nine months after grafting.
In Australia, small oval-shaped punches about
I centimeter long are being used on macadamia to
remove buds from ungirdled stems that are fitted
into punch-holes similarly created on the stock for
a perfect fit (83) in budding.
Figure 56. Young, succulent caney growth produced on branches
that were "hedged." These limbs are ideal for scion wood
when properly girdled for starch storage.