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

due to lack of chlorophyll formation, a complete
yellowing at the terminals indicating Fe deficiency.
In recent tests yet unreported, Shigeura
(73), using leaves and stems as index tissues, has
been able to show that manganese (Mn) can also
become a problem on lava land where excessive
phosphate has been applied. In another test on
soil order Inceptisols (suborder Andepts) at Honokaa
(72), Shigeura demonstrated that a reduction
in leaf concentrations of Mn, Ca, and Mg is associated
with an increase in P concentration beyond
0.10 percent in the leaf index tissue, suggesting
three possibilities: (l) that phosphate causes a big
flush of growth and "dilutes" other nutrients;
(2) tha t phospha te increases soil cation exchange
capacity and thus leads to lower solubility of
other nutrients; or (3) that cation fixation by
phosphate in the soil occurs with macadamia in
Hawaiian soils.
On the basis of a "recently matured terminal"
sampling, Shigeura et a1. (74) presented data suggesting
the optimum Ca level is 0.55 percent (Fig.
66). This value is not applicable using Cooil's
physiologically older leaves since older leaves
analyze at a higher level of Ca.
Workers in Hawaii on sugarcane, papaya, and
pineapple used recently matured leaves in their
foliar diagnostic work. Jones (31) and Jones and
Embleton (32), in their work on M. integrifolia in
California, used "matured spring growth" leaves,
which are essentially comparable to "recently
matured terminal" in Hawaii. Although the
advantage of the "recently matured terminal"
sampling is very real, onedanger with this method
is that sampling done by an inexperienced person
can include terminals not yet fully matured.
Immature leaves are distinctly softer to the touch.
However, with proper training and care in
sampling, this procedure is very easy to learn.
Boron (B) deficiency (24) is quite prevalent in
the Islands. On macadamia it manifests itself in
terminal dieback as in P deficiency; but unlike P,
B-deficiency symptoms show clusters of small,
leafy heads on the dying terminals. When a Bdeficient
tree is sprayed with soluble B, regrowth
takes place throughout the defoliated area and at
the very terminal branches (Fig. 67); regrowth
terminals appear lighter in color. Further work on
minor elements such as zinc, manganese, copper,
and iron is indicated.
The suggested leaf analyses values by the various
workers are given in Table 3.
100.0
8
93. 0
89.
18
A
f
. - .
. . .. . . . .
.1
. 3
. . -. .
.8
- ...-
.0 .
. .
( . :
3
.
14.
105
66.8
CALCIUM YS. QUALITY
(COMBINEDl
0.150 D.225 D.3OO 0.315 0.450 0.525 D.6OO 0.615 0.150 D.825
% CAlCIUM
Figure 66. No. I nuts as affected by percentage of leaf Ca. Except for
the stray point, the chart shows a widespread distribution
of points for No. I nuts below 0.4 percent Ca, and a relatively
confined distribution above 0.4 percent, becoming
beller confined at points above 0.55 percent.
Figure 67. Boron-deficiency symptoms showing regrowth (lighter
colored) on defoliated branches after B application.
I
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