Macadamia
Botany
 The macadamia nut is
native to the coastal rain forest areas of south Queensland and northern
New South Wales in Austrialia between 25 and 33 S latitude. It is a subtropical
nut and belongs to the same family as protea.
Two species that
produce edible kernels are Macadamia integrifolia, the smooth shell macadamia,
and Macadamia tetraphylla, the rough shell macadamia. Both species are evergreen
trees, often as tall as 60' spreading as wide as 40'. They have shiny, green,
holly-like leaves. M. integrifolia, the smooth shell, is the most important
species.
The fruit is a
follicle with a dull green pericarp (husk) that opens along one line enclosing
a seed (kernel, nut) in a hard seed coat (shell).
Smooth shell
The nutrient composition
of the roasted kernel (4 oz):
|
energy
|
820
calories
|
|
moisture
|
1.2-
1.5%
|
|
protein
|
9
%
|
|
fat
|
78
%
|
|
total
carbohydrate
|
10%
|
|
fiber
|
1.8
%
|
|
calcium
|
53
mg
|
|
phosphorus
|
240
mg
|
|
iron
|
2
mg
|
|
vitamin
a
|
0
|
|
thiamin
|
0.2
mg
|
|
riboflavin
|
0.1
mg
|
|
niacin
|
1.6
mg
|
Leaves
are 5 to 10 inches long, usually three at the same node. Some cultivars
(varieties) have smooth leaves, others have leaves that are more spiny
on the edges. Flower spikes are produced in racemes (clusters) 6 to 12
inches long consisting of hundreds of small cream-colored perfect flowers.
However, seldom do more than 10 nuts set on a mature raceme.
Rough shell
This
species (tetraphylla) produces slightly spindle-shaped fruits (nuts) with
rough pebbled surfaced husks. The leaves are 10 to 20 inches long and
produced in clusters of four, with spiny edges. Flowers are pink, and
the clusters are 8 to 15 inches long.
The
kernels have less oil and more sugar and though sweeter when eaten raw,
results in a darker nut when roasted of low quality.
Flowering and Nut Set
Contrary to Australia,
many growers in Hawaii note that the flowering period tends to lengthen
as an orchard matures, which may help to compensate for poor conditions,
pest or disease problems during a particular time. The natural maturation
and drop of macadamia nuts in Hawaii extends over periods of several months
and in some cases appears to be increasing. For the small grower who depends
upon family labor and for some processors, this is an advantage.For larger
growers, it would be ideal if macadamia could be cycled so that the maturation
and drop of nuts could be programmed over an extended period. High density
nuts could be harvested with less labor.Ethephon (Ethrel) is cleared for
use to enhance nut drop (abscission). Field research on 333 indicates that
application of ethephon at 400 to 500 ppm should be timed 26 to 33 weeks
after maximum flowering to achieve the most rapid and complete response.
Yield 1 to 3 weeks after treatment was increased, but total yield (5 weeks
after treatment) was not different from the unsprayed trees. However, some
defoliation of the older leaves is likely (Nagao, 1986, Proc. HMNA). Field
research is continuing.A combination of Ethrel treatment with mechanical
shaking has resulted in some increase in total sugar content and some decrease
in percentage of No. 1 nuts. This indicates that some immature nuts are
included in the drop and suggests successful application is most likely
where flowering is also controlled.
One of the factors
affecting flowering is temperature. In growth-room experiments, it was shown
that more profuse flowering resulted from night temperatures of 15°
to 18°C (59° - 64°F) than at higher night temperatures. However,
this control is not absolute, since eventually some flowering resulted when
night temperatures were 21°C (70°F). These results seem to corroborate
the frequent observation that macadamia flowers and matures earlier at higher
than at lower elevations.
Further experiments
suggest that nut formation has a higher optimum temperature range than flower
formation. Hence, overall response to temperature may be more complicated
than thought previously.The economic importance and the cause of the shrivel
kernel problem are not known.Nut set and premature nut drop.
Periods of high nut
drop have been identified in several varieties and appear to correlate with
the onset of exponential fruit growth (4-6 weeks after anthesis).Measurements
of ethylene production by intact racemes have shown higher ethylene levels
associated with periods when nuts undergo heavy drop (4-6 weeks after anthesis).
These experiments suggest that high ethylene production may be responsible
for premature drop of macadamia in the laboratory and under field conditions.Abscission
of young fruits in the field and on explants (in vitro) can be stimulated
by ethylene. Ethylene inhibitors such as silver nitrate and aminooxyacetic
acid delayed abscission of young macadamia nut explants. As fruits attained
full size, sensitivity to ethephon decreased. As fruit reached maturity
and began abscising, ethephon again promoted abscission.Experiment with
explants indicated that the growth regulators, NAA & 2,4-D, can inhibit
abscission of nuts in vitro. Gibberellic acid (GA3) and benzyladenine (BA)
had no effect.When individual racemes in field trials were treated with
GA3, NAA, or 2,4-D, GA had no effect in these experiments. NAA at 1.0 mM
stimulated abscission of young fruits, whereas 0.01 and 0.1 mM had no effect.
A temporary inhibition of nut drop was evident after treatment 0.01 and
0.1 mM 2,4-D; reapplication stimulated abscission.
Preliminary experiments
with N, P, K and zinc fertilization have shown that inclusion of zinc-containing
fertilizer significantly increased fruit set early in the season. Yields
were also significantly increased by the N, P, K, and zinc treatments. Preliminary
experiments at a commercial orchard suggest that supplemental irrigation
during dry conditions reduces premature nut drop.Girdling, when done to
the entire tree at the early flowering stage, enhanced flowering 14 to 18
weeks after treatment, and greater fruit set was observed. Girdling at the
maximum flowering and end of flowering did not affect flowering.Nut thinning
experiments, in which number of nuts per raceme were varied 4-5 weeks after
anthesis, showed initial nut set affected final nut set. Percent nut drop
was unaffected. Nut thinning experiments done on girdled branches showed
final nut set and percent nut drop were affected by girdling. Studies are
currently in progress to determine the relationship between leaf area and
premature nut drop.Results of recent experiments (unpublished, Nagao) on
flowering have shown that gibberellic acid (GA3) at 200 to 1,000 ppm inhibited
flowering of young trees when applied prior to the flowering season. A commercial
formulation of GA3 (Pro-Gibb) at 2,340 ppm also inhibited flowering. No
deleterious effects on vegetative growth were evident following treatment,
nor was flowering in the subsequent season affected. Experiments with the
GA antagonist, daminozide or succinic acid-2,2-dimethyl hydrazide (SADH),
at 700 and 7000 ppm applied at the same stage slightly inhibited flowering.
Ethephon at 100 to 500 ppm hastened flowering and shortened the duration;
total number of racemes was not affected.Preliminary results of photosynthesis
experiments revealed that leaves grown in full sun were saturated (maximum
level of photosynthesis) at light intensities 70% of the intensity at noon.
As leaves were grown in shade, leaves were saturated at increasingly lower
levels of light indicating adaptation to shade.Recent research in Israel
indicates that air layered trees begin bearing several years before grafted
trees. Earlier bearing would start positive cash flow earlier, enable growers
to adopt new cultivars by reducing the time orchards are non-productive,
and help to control tree size permitting closer planting. Research with
Paclobutrazol (Cultar), a growth retarding chemical, should also be initiated
to control size and promote early productio
Climate
The following set of
environmental conditions fall within the acceptable range for macadamia
production in Hawaii:
Soil: well-drained a'a
lava land that is sufficiently developed or weathered to support a solid
cover of natural vegetation, or other deep, well-drained soil with pH range
between 5.5 and 6.5.
Rainfall: 60 to 120
inches a year; 80 inches or more for lava land.
Elevation: Sea-level
to 2,500 feet.
Optimum yields occur
in areas with maximum temperatures less than 90°F (32°C) and minimum
temperatures greater than 55°F (13°C).
A rule of thumb
offered by some Australian scientists and supported by several Hawaii scientists
when considering planting outside Hawaii is not to plant between 0 and 25
N or S latitiude.
Educational Programs
CTAHR provides information
on production and marketing, and support to grower and processor organizations
through the Cooperative Extension Service. County Extension agents with
responsibility for fruit crops (including macadamia) are located on the
Big Island, Kauai, Maui, Molokai, and Oahu. These agents are supported by
a commodity extension specialist responsible for avocado, coffee, guava,
and macadamia located at the Manoa campus.
Other discipline
extension specialists with some assignment in macadamia include agricultural
economics, entomology, food science, soil science, and weed control and
are all located at the Manoa campus. Two more specialists in pathology and
agricultural economics with some assignment in macadamia are located in
Hilo.
Two agents cover macadamia
on Big Island; however, the agent on the Kona side is responsible for all
horticultural crops in Kona and Kohala. As this is a major macadamia, coffee,
and avocado area and one with an expanding landscape industry, he is unable
to cover any crop in depth. Another agent is needed in the Kona-Kohala area.In
addition to insufficient time to handle in-depth educational and applied
research programs at the extension agent and to a lessor extent at the specialist
level, budgets are insufficient to support travel--intraisland or interisland
and other operations.Most of the growers have small orchards, < 10 acres,
though most the acreage is on a few large corporate farms. Educational meetings
are scheduled during the evenings or weekends as small growers generally
have off-farm jobs.
Ag consultants and production
management firms have gained popularity in some parts of the US, particularly,
Florida and California. Absentee investors frequently utilize these services,
but the vast majority of growers in Hawaii cannot afford consultants and
depend on advice from agents. Corporate farms have their own staff and frequently
work directly with CTAHR (College of Tropical Agriculture and Human Resources)
scientists.New strategies to handle the increasing number of requests by
growers for on-farm visits, walk-in conferences, workshops, special programs,
and applied research must be developed. The use of video taped programs
of field days and specific production tasks is being explored. A video bulletin
on a small innovative grower has been edited. Agents also encourage local
grower groups to sponsor field days to share production skills and as venue
for agents to work with larger numbers of growers.Horticulture Department
scientists have developed an information system on tropical crops in Hawaii
called the Farmer's Bookshelf. Originally developed in 1988 for use on Macintosh
computers, a Windows version was later added. Currently, the Macintosh and
Windows versions are no longer supported since the Farmer's Bookshelf was
put on the World Wide Web in 1997.The last major extension bulletin on macadamia
was published in 1984. A short bulletin, HITAHR Brief No.057, was published
on weed control in 1987. The 4th Macadamia Industry Analysis (1987) was
released as a bulletin.
The macadamia specialist
also edits and video tapes the proceedings of annual meeting of the H.M.N.A.
which provides additional technical information the more educated growers,
ag consultants, extension agents, and other scientists.
Computerized Macadamia
Costs Analysis
The Macadamia Cost Analysis
file for macadamia has been developed by Dr. Kent Fleming, ,
fleming@hawaii.eduHorticulture Dept., CTAHR (808-322-9136), to help
farmers determine their costs and profits. Simply read the brief instructions
at the top of the file when it opens. Type in your numbers where or use
the 'typical farm' numbers in the bordered boxes, the analysis is automatic.
You will need a spreadsheet program such as Lotus 1-2-3 or Microsoft Excel.
A printout of
this analysis for a typical farm is shown in Hawaii Macadamia Nut Assn.
(1992) 32nd Annual Proceedings, p. 65.
EXTENSION BULLETINS 
Economics of Macadamia
Nut Production in Hawaii by Dr. Frank Scott (Research series 059, 1989)
is available from most Cooperative Extension Service offices in Hawaii.
This publication considers startup and annual costs yearly, based on 25,
50, 100, and 500 acre farm size.
Annual per acre
net returns to land and risk for the four farm models at year 16 indicate
substantial economies of scale, ranging for $3,075 for the 25 acre to $3,853
for the 500 acre farm at an in-shell price of 90 cents per pound and an
in-shell yield of 6,500 pounds per acre. Use of mechanical harvesters contributes
to the greater efficiency of the larger models, with shakers becoming economically
feasible at year 12 for the 100 acre farm and year 8 for 500 acre farm.
Substantial economies of scale are also reflected in orchard development
cost, which is considered the total cost of financing the orchard through
year 6 and ranges from a high of $17,250 per acre for the 25 acre farm to
a low of $13,780 for the 500 acre farm.
Internal rate
of return before tax (pre-1987) at an in-shell price of 81 cents per pound
(approximately the current level) and inflated at 5 percent annually is
submarginal for all six models ranges from 15.3 % for the 25 acre farm to
19.3 % for the 500 acre farm.
For smaller farm sizes,
HITAHR Brief 009, Economic viability of small macadamia nut farms in Kona
written by Scott and Marutani 1982 might be helpful. This out of print bulletin
may be available at Cooperative Extension Service offices in Hawaii.
Cultivars
The following cultivars
are recommended by CTAHR:
'Purvis (294)
- produces large kernels of exceptionally good quality and flavor.
'Kau' (344) - hardy,
upright tree well adapted to elevations from 500 to 2000 ft.
Average Yield,
Waikea Experiment Station:
5970 lbs WIS,
1920 lbs. of kernels, 1560 lbs. No.1 kernel per acre.
(Ito, Hamilton and Hirae, 1983, Tropc. Agric. 60:64-65).
'Kakea' (508) - very
heavy producer of high quality nuts and kernels over a 5 to 6 month harvest
period, somewhat susceptible to 'stick-tight' nuts.
Average Yield,
Waikea Experiment Station:
5520 lbs WIS,
1930 lbs. of kernels, 1663 lbs. No.1 kernel per acre.
'Keaau' (660) - upright
tree with excellent nut and kernel characteristics, crop matures over a
3 month period.
Average Yield,
Waikea Experiment Station:
4780 lbs WIS,
1750 lbs. of kernels, 1500 lbs. No.1 kernel per acre.
'Mauka' (741) - hardy
tree which performs well from 1500 to 2000 ft. elevation.
'Pahala' (788) - narrow
and upright tree with excellent nut and kernel characteristics.
'Makai' (800) - produces
excellent kernel quality and is adapted to 500 to 1800 ft. elevations.
Some large growers prefer
cultivars with short harvest seasons, while some small growers prefer cultivars
with longer harvest seasons; both types are available.Some processors do
not want a short harvest season because this would create shelf-life, storage,
and capital problems.Current selection standards used by the CTAHR breeding
program strives for:
in-shell yields of 150
lb per tree at 10 years, at good sites and 80 lb. at less favorable sites;there
should be few to no 'stick-tights', 60 to 85 nuts per pound with 37 to 45%
kernel, at least 95% grade 1 kernels with specific gravity < 1.0, kernel
appearance score of 3.0 to 3.5 on a scale of 4.0;the tree should be narrow
and upright with strong crotch angles to permit a tree spacing of 20 x 30
ft. without shading adjoining trees.
A project funded by
a USDA section 406 grant is evaluating different cultivars for postharvest
problems caused by genetic susceptibility to rancidity.From current indications,
including new selections and genetic material on hand, in-shell production
per tree can be increased by at least 25%, the percentage kernel recovery
increased from 35 up to 45%, the percent of grade 1 kernels per tree can
be increased from 85 to 95% with new cultivars. The potential increase would
amount to approximately 80 percent higher yield of grade 1 kernels.
Cultivars with good
yields at altitudes up to 2000 ft. are 'Mauka' - 741, 'Keaau' - 660, 'Kakea'
- 508, and several unnamed selections. A longterm, replicated evaluation
program organized to collect yield, growth, and to observe genetic x environment
responses of different cultivars in a range of ecozones and locations is
only partially organized.Selections resistant to the root disease Kretzschmaria
clavus root rot are needed. Two projects have been initiated to screen seedlings
as possible rootstocks resistant to Kretzschmaria clavus.Vigorous-growing
rootstocks adapted to problem soil areas such as the low pH, phosphorus-fixing,
high manganese and aluminum soils are needed. At present, there is only
limited information on rootstocks. M. tetraphylla is not recommended at
a rootstock for Hawaii due to questionable performance.Growers sometimes
experience reduced nut quality when nuts are left longer than a month on
the ground particularly with the cultivars 'Keaau' - 660 and 'Mauka' - 741.
Germination tests are included in the current selection program to discard
plants which tend to germinate quickly.Limited amounts of scionwood of new
cultivars can be obtained from CTAHR as they become available. Large and
small growers are also sources of propagating materials when commercial
quantities of scions are required as there is not a developed commercial
nursery industry for macadamia plants comparable to other mainland fruit
crops.
Diseases
A fungus, Kretzschmaria
clavus, was isolated from decayed roots of macadamia and shown to be the
causal organisms of root rot on healthy macadamia trees. An estimated 6,500
acres of bearing and non-bearing macadamia trees or 44.2% of the total acreage
in the State of Hawaii are currently planted in areas where K. clavus has
been identified. In Hilo and vicinity, more than 80% of declining macadamia
trees had extensive root rot caused by K. clavus, and the severity of tree
decline was positively correlated with the amount of root rot. K. clavus
is only one of several types of decline.Trees that decline are usually 10
to 12 years old. The effect of K. clavus on younger trees is not known.
It is sometimes difficult to re-establish a tree in the area previously
occupied by a tree that declined.
K. clavus was found
on trunks of dying or dead Melochia indica and Cecropia peltata in ohia
forests near the macadamia orchards with K. clavus root rot in Keaau. The
fungus isolated from these two species of trees was capable of infecting
healthy macadamia trees. This indicates the possibility of reducing the
damage by K. clavus in the new plantings by changing cultural practices.
Instead of the conventional practice of incorporating the stem tissues of
forest trees into the soil, they should be removed from the field.
The following field
observations suggest that root rot of macadamia caused by K. clavus may
also be air-borne:
Kretzschmaria root
rot of macadamia occurred in a field previously planted with sugarcane.In
a rainy area, the tree death rate was relatively high. More than 50% of
macadamia trees were killed by K. clavus within 5 years.In the same area,
infection originating from a branch more than 1 m above the ground was
observed on several macadamia trees. The source and origin of air-borne
infection is still unknown. This information is vital for the development
of control methods.
Obstacles to finding
an effective fungicide control program for K. clavus are:
The early stages of
infection are difficult to detect.Most systemic fungicides are xylem translocated
so the they move to and accumulate in the leaves. A downwards mobile fungicide
would be most effective for K. clavus control.
He industry
is surveying its orchards to identify possible root rot resistant rootstock.
There is no evidence yet of such a rootstock. Furthermore, present commercial
varieties are susceptible to air-borne infection by K. clavus which a
disease resistant rootstock would not protect. Acreage within the affected
areas is expected to increase considerably before a disease resistant
rootstock can be identified and propagated for commercial planting.
Macadamia seedlings
inoculated with K. clavus grown in wheat and oat medium died within one
month in preliminary tests. This method is currently being used to screen
macadamia seedlings for resistance to K. clavus.
Botrytis blight occurs
on macadamia blossoms only after anthesis or on senescent flower parts.
Flower buds and even very young nuts are not susceptible.
Phytophthora
blight occurs only after prolonged periods of continuous rain. Infected
racemes and nuts were found only on particular branches or sections of
a tree rather than distributed evenly throughout the tree because the
fungi produced only a few sporangia on racemes and none on the nuts. As
soon as the rains subsided, no further spread was observed. Even with
occasional light rains and 100% relative humidity every night, the pathogens
did not become active again.
Botrytis and Phytophthora
blights may only be a problem 2 out of 5 years and are generally not considered
serious except for localized outbreaks. The effects of these blights could
be magnified if the flowering season were concentrated in a short period
of time. Benlate at 1-3/4 lbs. per acre and Difolatan at 114 lbs per acre
are recommended for these blights. Only the large growers have a spray
program.Experiments performed by CTAHR have not demonstrated increased
yield to result from control of these organisms. However, industry says
it has experienced as much as 30% reduction in yield from the blossom
blights.Since these fungi might develop resistance to Benlate (as in the
case of Botrytis) and Difolatan has been discontinued by Ortho and only
remaining stocks will available, alternative chemicals should be identified
and registered.Ridomil was found to be effective in field tests but only
at 2 and 4 oz. (active) per square meter applied as a drench. This rate
is not cost effective. Because of resistance problems Ridomil 2E will
not be registered for foliar applications. Aliette, a product specific
to Phytophthora and Ridomil MZ 58, a combination of Ridomil and Mancozeb
has shown efficacy in controlling Phytophthora blight in limited field
testing. Further testing and residue analysis are continuing.A flower
blight scouting program could be feasible because of the macadamia blooming
cycle. Flowers could be collected and checked to determine if population
levels of the fungi have reached economic thresholds. Scouting could begin
with early bloom and collections could be made from representative areas.
Results could then be returned by electronic mail to initiate fungicide
applications if required. Correlation of collection information with weather
data could provide the basis for a future forecasting system.
Phytophthora cinnamomi
causes stem canker of macadamia. It is relatively rare, but increased
incidence of this disease has been associated with poorly-drained sites,
seedlings planted too deeply, and mechanical injuries.
Fertilization
The fertilization practices
for a location should be determined by monitoring the concentration of the
major nutrients in the leaves annually or more frequently. The standard
procedure for collecting leaf samples for tissue analysis and interpreting
the results is described below based the work of Dr. Bruce J. Cooil, Ag.
Botany, CTAHR, and modified in 1987 by Dr. John E. Bowen, Plant Molecular
Physiology (Proceedings 27th Annual Meeting of Hawaii Macadamia Nut Assn.)
Leaf Sampling:
Leaves are sampled
during the month of the year when the major flush of growth is beginning.
At Keaau Orchard, this is generally in March. Branches are selected on which
new growth is just beginning. (We have used only such branches which can
be reached from the ground, as branches higher in the tree would require
more labor than available.)
From each selected
branch, one mature leaf is taken from the second whorl below the newly developing
flush. Where single trees are sampled, the sample should contain at least
8 leaves, each from a separate branch. The selected branches should be obtained
from different positions around the tree. If samples are being composited
from several trees, ordinarily a minimum of three leaves should be obtained
from each tree.
For analysis of
N, P, K, Ca, and Mg, the sample should contain at least 8 leaves. If minor
elements are also to be determined by chemical methods, the sample should
consist of at least 15 leaves.
Interpreting Analytical Results:
For leaves sampled
as described above, interpretations of nutritional status have been made
as shown below. These values are based on experiments with 'Keauhou' (246),
'Kakea' (508), and 'Ikaika' (333) and recent work on seedlings of 'Keaau'
(660) and 'Pahala' (788).
Results indicate
that the critical ranges for nutrients are similar in these tree selections.
Insufficient information is at hand to determine whether this is also true
of other selections. Values are reported on the basis of leaf dry weight
and dependent upon on the relative concentration of the nutrient in percent
or in parts per million (ppm) also called g/g.
Nitrogen (N): Young
trees before bearing age should have leaf nitrogen values in excess of 1.50
percent (dry weight basis) for maximum growth rate. Leaf concentrations
below this are generally associated with light-green or yellowish color.
In older bearing trees, the leaf nitrogen may go as low as 1.45 percent
N without loss in yield.Potassium (K): Potassium concentrations of 0.45
percent of the leaf or above clearly denote adequacy for growth of young
trees and yield of bearing trees. Concentrations below 0.30 percent K generally
denote deficiency, which may become severe. Severe leaf scorch is found
in this range. In the range between 0.30 percent K and 0.45 percent K, deficiency
may develop if potassium is not available at all times, as may result if
applications are infrequent. Recent work on seedlings of 'Keaau' (660) and
'Pahala' (788) suggest slight deficiency at 0.45 percent but good growth
at 0.6 percent.Phosphorus (P): A leaf concentration of 0.08 percent P (dry
weight basis) or above is needed for maximum growth rate of young trees.
To assure maximum yield of bearing trees, a value of 0.08 or higher should
be maintained. Leaf phosphorus percentages above 0.20 percent of dry weight
are associated with chlorotic and firing symptoms, so should be considered
excessively high.
In soils having
low phosphorus-fixing capacity (e.g., unweathered lava), excessive phosphorus
can lead to immobility of iron in the plant and the appearance of iron-deficiency
symptoms (chlorosis in leaves); under such conditions, a phosphorus level
of 0.12 percent can be excessive.
Magnesium (Mg): Leaf
magnesium values of 0.065 percent (dry wright basis) or below are definitely
associated with an interveinal chlorotic mottling of older leaves. However,
no response in growth or yield has resulted from application of magnesium
to 'Keauhou', 'Kakea', or 'Ikaika' even in this low range. Recent work on
seedlings of 'Keaau' (660) and 'Pahala' (788) suggests that below 0.09 to
0.10 percent is inadequate for maximum growth.Calcium (Ca): Leaf calcium
values of 0.65 and above are considered adequate, 0.55 is the critical minimum.
Recent work on seedlings of 'Keaau' (660) and 'Pahala' (788) suggests that
deficiency symptoms are present at 0.57 percent.Iron (Fe): Recent work on
seedlings of 'Keaau' (660) and 'Pahala' (788) suggests that leaves containing
60 ppm Fe were free of deficiency symptoms, but symptoms were observed at
33 ppm. In bearing trees this value maybe be lower.Zinc (Zn): Recent work
on seedlings of 'Keaau' (660) and 'Pahala' (788) suggests that leaf zinc
>30 ppm is adequate, with symptoms appearing slowly at 17 ppm. In bearing
trees 15- 20 has been considered adequate in the past.
Boron (B): Recent work
on seedlings of 'Keaau' (660) and 'Pahala' (788) suggests that leaf B should
be > 50, in bearing trees 75 ppm B has been recommended in the past. Deficiency
symptoms are apparent at < 15 ppm B.Copper (Cu): Recent work on seedlings
of 'Keaau' (660) and 'Pahala' (788) suggests that 11 ppm leaf copper is
adequate. Deficiency symptoms were very slow to appear. In bearing trees
4 ppm Cu has been recommended in the past.Manganese (Mn): Recent work on
seedlings of 'Keaau' (660) and 'Pahala' (788) suggests that 48 ppm Mn leaf
is adequate, with deficiency symptoms manifested at 25 ppm Mn. In bearing
trees 100 ppm Mn has been recommended in the past.Length of time to express
deficiency symptoms when a single nutrient has been totally withheld from
8 months old seedlings is shown:
|
Nutrient
|
Months
to Visual symptoms
|
appearance
of Reduction in growth
|
|
N
|
2
|
4
|
|
P
|
2
|
3
|
|
K
|
3
|
4
|
|
Ca
|
4
|
7
|
|
Mg
|
5
|
none
after 26 months
|
|
Fe
|
6
|
12
|
|
Zn
|
12
|
15
|
|
B
|
8
|
13
|
|
Cu
|
15
|
none
after 26 months
|
|
Mn
|
11
|
none
after 26 months
|
Leaf and soil analysis
services are available from several private laboratories and the Agricultural
Diagnostic Service Center (ADSC), CTAHR at cost. Grower use of the ADSC
increased 125% and 37% for tissue (345 samples) and soil (272 samples) analysis,
respectively, from 1985 to 1986. The number of samples received by August
in 1987 was 56 and 61, tissue and soil, respectively. This appears to indicate
a greater need to demonstrate the cost effectiveness of these diagnostic
services to smaller growers.Field experimentation is insufficient for precise
correlating, tissue, and soil analysis results.
No significant results
have been obtained from two earlier field two experiments that have been
conducted on the effect of minor elements on yield. One experiment was conducted
in Mac Farms of Hawaii's orchard, and the other was conducted in Keaau.The
soil need not be monitored as frequently once classification and initial
nutrient status is assayed. Occasional check of soil pH might be worthwhile
especially in areas with high aluminium and/or manganese and low pH <
5.0.
Harvesting
The main harvest period
for macadamia extends from August through January. In some areas, nuts mature
throughout the year. Nuts fall to the ground and can be gathered by hand.
Pickup should be within a month, sooner if conditions of high rainfall,
rat or pig-damage are likely. Nuts should not be stored in the husk.
Most growers then
sell their nuts in husk to processor, for husking, drying and cracking.
Mechanized Harvesting
Formerly, large growers
such as Mauna Loa and MacFarms used either shake harvesting or mechanical
sweepers for nut harvesting. Manual pickup is generally used to harvest
low density nuts on the ground in the early or late season. Shake harvesting
was discontinued at MacFarms due tree injury and longer harvest season which
resulted in smaller percentage of mature nuts at any harvest date. A shake
harvester cost approximately $40,000 to $50,000 and can harvest approximately
200 acres.
The harvesting
acreage could be increased significantly if an economical and reliable nut
ripening monitoring process could be developed and tree injury reduced.
Increased harvesting area per shaker would certainly bring harvesting cost
down.
MacFarms has a contract
with a mainland company to develop a vacuum harvester. Testing should begin
in the 1987 season; a joint venture with Mauna Loa is being discussed. The
harvester would be used in conjunction with an as yet untested system utilizing
moving, rock crusher and replacement of husks on the orchard floor to decrease
roughness and improve water and nutrient holding capacity.A small harvester
developed by CTAHR is currently mounted on a 16 hp 316 John Deere tractor
powered by an auxiliary 25 hp engine tandem-mounted for hydraulics. When
used commercially, it should be mounted on at least a 45 hp tractor with
PTO. Testing at CTAHR's Waimanalo farm in the 1986 season, the achieved
harvesting rates of 200 lbs/hr (in husk) including time for off-loading
nuts and fueling. Assuming the harvester has > 50% pick up efficiency and
hand harvesting of 50 lbs/hr, it should reduce picker labor by 90%. The
harvesting swath is 8 feet. Leaves and other trash are separated from the
nuts, and shredded, new shredding device is being developed.
Further information
on this experimental harvester for manufacturing and extension is available
from Dr. Tung Liang (tliang@hawaii.edu),
Biosystems Engineering Department, Univ. of Hawaii, Honolulu, HI 96822.
Estimated cost is $15,000 without the tractor.
An Biosystems Engineering
Master's thesis was written on hard surface roughness in terms of harvesting
efficiency. Copy in the UH Hamilton Library, Daniel Paquin (1984) (paquin@hawaii.edu).The
need for proper land preparation to facilitate mechanical harvesting is
understood by the industry.Ethephon (Ethrel) is cleared for use to enhance
nut drop (abscission). Field research on 333 indicates that application
of ethephon at 400 to 500 ppm should be timed 26 to 33 weeks have maximum
flowering to achieve the most rapid and complete response. Yield 1 to 3
weeks after treatment was increased, but total yield (5 weeks after treatment)
was not different from the unsprayed trees. However some defoliation of
the older leaves is likely (Nagao, 1986, Proc. HMNA) (mnagao@hawaii.edu).
Field research is continuing.
Industrial Organization
The Hawaii Macadamia
Nut Association (formerly Hawaii Macadamia Producers Association) has been
serving growers and processors in the state for over 27 years.
An interested person
can join, though emphasis is on commercial growers and processors in Hawaii.Current
membership is over than 200.The board of directors has 18 members representing
growers from different islands and districts of Big Hawaii such as Hilo
Macadamia Producers, Kohala Macadamia Growers, Kona Farmers Coop, Pacific
Cofffee Coop, processors and production/processing corporations. Board members
remain on the board for long periods. Officers are nominated from the board
by a combination of geographic rotation and nominating committee. Election
is finalized by a voice vote at the annual general membership meeting.The
annual meeting serves to conduct HMNA's general membership business and
as an educational meeting. Speakers are generally CTAHR scientists presenting
research reports, innovative growers, DOA officials, and officers of the
major corporate farms.There two large production/processing corporations--Mauna
Loa, a subsidiary of C. Brewer Co., and MacFarms, with orchards over several
thousand acres. They control more than 80% of the production. There a few
corporate farms with hundreds of acres, and over 600 farms with less than
a hundred acres, most less than 10.Currently, membership dues are set at
$10 per year. In the past, various assessments were attempted to raise money
to support HMNA activities and project. Assessments on acreage and production
have been unsuccessful. Either corporations were assessing themselves large
sums of money without equal control of HMNA policy and projects, or processors
were unwilling to collect and turn over assessments from growers. Due to
the vast differences in size small growers have been reluctant to what pay
what some consider substantial sums as well.For a number of years Mr.'Porky'
Oka served as staff member to the HMNA. He has since retired, and no staff
have been hired. Without a full time staff member it is impossible to oversee
any of projects, meet service goals assigned by its members, and hold an
annual education meeting.For the HMNA to meet its responsibilities leading
diversified agriculture industry in the state, it must have at least one
fulltime director with managerial skills and vision and an annual budget
of at least $100,000.
Land
The following set of
environmental conditions fall within the acceptable range for macadamia
production:
Soil: well-drained a'a
lava land that is sufficiently developed or weathered to support a solid
cover of natural vegetation, or other deep, well-drained soil with pH range
between 5.5 and 6.5.Rainfall: 60 to 120 inches a year; 80 inches or more
for lava land.Elevation: Sea level to 2,500 feet.
The Hawaii Natural Resource
Information System (HNRIS), a computerized geographical information system,
has been developed by CTAHR which catalogs land, soil, and climate information.
Information can be retrieved for land use such as macadamia production.
An inventory of agricultural
land (Hawaii island only), identifying suitable macadamia nut land, has
been completed using this system. The successful development of a production
function that predicts macadamia nut yield based on the environmental factors
and soils of the land has made the inventory possible. The availability
of a computerized database capable of supplying the needed environmental
and soil characteristics of large areas of land has drastically reduced
the inventory cost. The inventory is displayed in map form for reference.The
production function was derived by using yield data from experimental plots
maintained under management conditions which may differ from those of industry.
Therefore, the yield potential displayed in the maps should be used cautiously.The
computerized database was derived from the records of a small number of
weather stations and the Hawaii soil survey. It cannot be expected to provide
precise environmental information to the production function. The yield
map, therefore, should be looked upon as a guide to potential areas which
warrant serious on-site study before investment.A report describing the
system and displaying the inventory is available. For specific information
contact Dr. Tung Liang (tliang@hawaii.edu),
Dept. of Biosystems Engineering, University of Hawaii, Honolulu, HI 96822.A
better method for land evaluation is being researched.USDA-SCS has developed
a macadamia nut land potential rating for most soil series found on the
Big Island.
Although Hawaii Revised
Statutes Section 171-37 limits State land leases for intensive agricultural
uses to 35 years, the lease term can be up to 45 years for tree-crop orchards,
55 years if extensive expenditures are required, and 75 years if the lessee
is required to reside on the premises. Department of Land and Natural Resources
(DLNR) should be consulted as to applicability of these provisions to the
development of specific macadamia orchards.The industry increased from 475
farms, 13,300 acres in crop (10,000 bearing) in 1980 to 645 farms, 21,300
acres in crop (14,400 bearing) in 1986. New plantings decreased to only
400 acres in 1986.
With land leased from
the State, growers may pay as low as $5-$10 per acre per year for the first
few years, but will have to share a percentage of gross sales. Other land
can be leased for $30 to $120 per acre per year, plus lease purchase. Fee
Simple land costs between $2000 and $8000 per acre. Land with mature trees
sell for $10,000 to $20,000 per acre.Construction of the Panaewa Agricultural
Park begun in the fall of 1980 and was completed and lots were leased in
December, 1981. It includes 6 lots of 20 acres in size for macadamia production,
22 lots for other orchard and nursery crops, and a 110 acre lot for the
University of Hawaii at Hilo farm laboratory.
There has been
much interest expressed on the acquisition of land for macadamia. More agricultural
parks are desirable; it may be the only way for many small growers to get
into the business.
Some former sugarcane
lands in Honokaa, Kohala, Hilo, Kau, and Wailuku are now being used for
macadamia. Macadamia may be a good alternative for other sugarcane lands
that go out of production. More land (formerly under sugarcane) is being
made available for macadamia expansion. New plantings are expected on Kauai.Soil
erosion can be a problem in certain areas. Plans for land clearing must
be approved by the County to insure proper erosion control is incorporated
in the development of new orchards. USDA's Soil Conservation Service can
assist and should ideally be consulted prior to orchard planting. Terracing
and ground covers could prevent erosion (although ground covers could hinder
harvesting). In mature orchards, dense canopy shade out ground cover. Growers
on sloping land with soil need shade tolerant ground covers to prevent erosion
after orchards have closed-in.
Marketing
Annual statistics on
in-shell production, farm price and total sales are produced by Hawaii Macadamia
Nuts, Annual Summary Hawaii Agricultural Statistics Service, (HASS) DOA,
USDA cooperating.
Imports of macadamia
nuts into the United States as tons of kernels and value by country and
by port of entry were available for the first time for calendar year 1982,
compiled from U.S. Dept. Commerce data and have been published and disseminated
by HASS/DOA since 1982. U.S. macadamia exports are now available in a report
with the U.S. imports compiled by Dept. Commerce from the Foreign Agricultural
Service. It may also be possible to obtain permission from Matson Shipping
Lines to use their mainland shipments of macadamias as an indication of
Hawaii exports.
The value of the macadamia
industry as other agriculture industries is grossly undervalued if only
the farm value is used. Significant value is added by the time the product
is sold wholesale as dry kernels, and retail as salted nuts, in candies,
and other products.
A crude estimate
of the wholesale value of Hawaii-produced kernels in 1986 on 11 million
pounds of kernels (assuming 25% recovery from 44 million pounds of wet in-shell
nuts) was $105 million in 1986 compared to $35.2 million as farm sales).
An estimated 57% was sold in Hawaii for $50 million and 43% outside the
state for $54 million. The estimated value of macadamia products sold retail
in Hawaii in 1986 was $66 million, two thirds as snack nuts and one third
as chocolate candy. No estimates were available for the retail value of
other macadamia products such as cookies, ice cream, or of macadamia products
sold on the mainland or elsewhere.
A new CTAHR project
is being develop to more precisely estimate the value-added to various commodities
to show show more clearly the links to employment in other industries.
Demand is increasing
for macadamia oil by the cosmetic industry, especially in Japan. MacFarms
is investigating the development of a oil pressing facility to handle immature
and culled nuts, brokens, and fines. Value-added is increased substantially
if oil can be pressed, partially refined, and sold directly to a cosmetic
company. No values are reported for the potential value for this product.
A press to handle the much of the industries volume would cost $80,000.
Press cake has value as an animal feed.
According to projections
made by Scott (CTAHR, 1975), a fully developed U.S. market for macadamia
nuts could absorb 32.2 million lbs. of kernels by 1990.
It is estimated that
the U.S. consumption of tree nuts is now about 50% of world commercial consumption.
Based on this estimate, the potential world market for macadamias would
amount to 64.4 million lbs. of kernels annually. The major consumers outside
of the U.S. are the Western European countries and Japan. A reasonable sales
potential for Hawaii's industry might approximate the fully developed U.S.
market.Although Hawaii is the major producer of in-shell macadamias, wholesale
kernels and finished macadamia products, expanding foreign production is
decreasing Hawaii's market share. The US macadamia industry, predominantly
in based in Hawaii or affiliated with mainland food manufacturers, imports
about 10% of its kernels to meet demand which can not be met by production
in Hawaii.
Foreign competition
is not strong now, but has the potential of becoming serious. Earlier this
decade the leading foreign exporters of macadamias to the US were Kenya,
Republic of South Africa and Guatemala, in 1986 the exporters to the US
in order of volume were Australia, Guatemala, South Africa, Costa Rica,
Malawi, Zimbabwe and Brazil.
Sources of nuts
imported into the United States in millions pounds of dry kernels:
Country Year
1982 1983 1984 1985 1986
Australia 0.023 0 0.130 0.590 0.610
Brazil 0 0 0 0 0.030
Costa Rica 0 0 0.002 0.016 0.070
Guatemala 0.150 0.150 0.270 0.200 0.610
Kenya 0.220 0.220 0.078 0.042 0
Malawi 0 0.002 0.012 0.012 0.066
South Africa 0.140 0.120 0.380 0.510 0.340
Zimbabwe 0 0 0 0 0.004
Production in foreign
countries was discussed in several Proc. HMNA articles and most recently
by Ito and Hamilton and Davis in Proc. HMNA 25 (1985), and by Vidgen in
1987 HMNA annual meeting. From Proc. HMNA 25, two articles on foreign acreage
in macadamia reveal how difficult it is to estimate with any confidence.
Ito and Hamilton best estimates in 1985 are presented below with the most
recent US import data and Vidgen and Leeson 1987 and 2000 world production
estimates.
|
Country
|
Species
|
Tree
Age (yrs in 1985)
|
Tree
Yield in-shell (lbs/tree) in 1985
|
Production
Estimate (million lbs of kernels)
|
| 1987 |
2000 |
| Australia |
>90%
smooth |
10 |
15 |
2.2 |
8 |
| Brazil |
>50%
rough |
6 |
0.3 |
- |
- |
| California |
rough |
10+ |
20 |
- |
0.1 |
| Costa
Rica |
smooth |
9 |
10 |
0.4 |
6.0 |
| Guatemala |
smooth |
8 |
8 |
0.3 |
0.4 |
| Kenya |
>85%
smooth |
10 |
0.5 |
0.4 |
0.2 |
| Malawi |
>85%
smooth |
7 |
2 |
0.2 |
0.2 |
| S.
Africa |
80%
smooth |
7 |
0.7 |
0.5 |
0.5 |
| Zimbabwe |
>85%
smooth |
7 |
1 |
- |
0.4 |
| Hawaii |
smooth |
10+ |
64 |
10.7 |
20.0 |
| World
(total) |
|
14.7 |
35.8 |
In the early 1980s, the industry faced a "soft" market and "temporary"
gluts due to various reasons including the economy.
Insect Pests In The Orchard
Pests
of macadamia orchards in probable order of importance are the:
koa seedworm (Cryptophlebia illepida)
litchi fruit moth also called macadamia nut borer in Australia (C. ombrodelta)
southern green stinkbug (Nezara viridula)
macadamia nut borer (Polyphagotarsonemus latus)
Hawaiian flower thrips (Thrips hawaiiensis)
redbanded thrips (Selenothrips rubrocinctus)
black citrus aphid (Toxoptera aurantii)
Van Duzee treehopper (Vanduzea segmentata).
Koa
seedworm and litchi fruit moth
Eggs are deposited
on the surfaces of the husks and hatch in 3-5 days. Caterpillars tunnel
immediately into the husks where they feed under the surface. Caterpillars
mature in 16 days and pupate within the husk near an exit hole. An inconspicuous
brown moth emerges in 8-12 days. Adults are active at night, and females
can lay more than 300 eggs during their lifespan.
Recent reports
from Australia indicate that Cryptophlebia spp. are a major pest of macadamia,
in Africa, Australia (as high as 60% losses in orchards near urban areas),
and Central America. In Hawaii losses were thought to occur primarily when
caterpillars bore through the shells and feed on the kernels. This apparently
occurs when the nut shells are rather soft because there are higher rates
of damaged nuts early during the harvesting season. In other areas and most
recently in Hawaii it is realized that caterpillar feeding damage in the
husks can result in immature nut drop in addition to the normal June drop.
In the past, some farms in Honokaa reported 15-50% losses, most recently
the damage has been reported in Kona as far south as Honomalino.
MacFarms has instituted
a moth trapping and nut sampling program utilizing light and pheromone traps
and sampling nuts, both on trees and on the ground quantify the population.
Accurate information on losses is required in order to determine whether
it is economically feasible to apply controls.
Chemical control
does not appear feasible because of the pest biology. Even in Australia
where established monitoring methods and cypermethrin, a synthetic pyrethrin,
applied with ground equipment are used, the control is only marginal. In
Hawaii, registration of a new chemical and a more sprays per crop due to
our longer flowering period would be necessary.
In Malawi, disrupting
the mating of adults with mass aerial application of pheromone has been
successful. An Australian system incorporates pheromone into a small wick
and placed in tree. The wicks last up to a six months and costs 40 to 50
cents a tree. The wick and pheromone might require registration. Research
to test efficacy is necessary.
Ten species of parasites
were recorded for Koa sees worm in Hawaii in 1956 (Namba, Proc. Haw. Entom.
23), but no information exists on how much control they exert. This information
is needed before a decision to search for other parasites including egg
parasites such as the wasp (Trichogrammatoidea fulva). Importation of new
parasites could take more than a year, and there is no guarantee that it
would establish in Hawaii.
Southern green stink bug.
This pest has
a wide host range in Hawaii. Common host plants are Crotalaria spp., Amaranthus
spp., Desmodium spp., Asystasia sp., and spiderweed, but many other weeds
and vegetables are good hosts. Leguminous plants are commonly preferred.
Immature stages
and adults have sucking mouthparts and feed on succulent plant parts as
well as fruits. Stink bugs can penetrate the hard macadamia shell to feed
on the kernel for a short period. Although this pest is considered a serious
pest of macadamia because of the damage to nut kernels, no breeding on macadamia
has been observed.
CTAHR entomologists
have studied the ecology of the stink bug in commercial as well as experimental
macadamia orchards. The results showed that stink bugs preferred to remain
on weeds such as Crotalaria bordering the edge of orchards, and that there
was no increase in nut damage despite the presence of breeding population
of stink bugs on Crotalaria plants which were found throughout the experimental
orchard.
Although stink
bugs can readily be controlled using currently registered insecticides (malathion
and endosulfan), application of these insecticides is normally not needed
in macadamia.
Several species
of parasitic insects were introduced for controlling this pest. Two of the
more important are a fly parasite (Trichopoda pennipes) of stink bug adults
and a wasp parasite (Trissolcus basalis) of stink bug eggs. Both parasites
are very effective. The parasitic fly finds stink bugs by homing in on an
odor which male bugs have. It is not known how the parasitic wasp locates
stink bug egg clusters, but the wasp parasitizes all of the eggs in the
cluster (80-120 eggs) which it locates. The fly parasite requires a nectar
source, and it was found that Crotalaria is an acceptable source.
It is believed
that much of current damage to nuts can be attributed to stink bugs which
enter macadamia fields after certain weed host plants such as spiny amaranth
die, or to the practice of utilizing stink bug hosts as ground covers. Damage
can be minimized by utilizing the "trap-border" method. Crotalaria border
plantings can be utilized to attract and hold stink bugs which would normally
damage macadamia. One test reduced damaged from 16 to 3%. In this way parasites
can then easily locate and control the pest. Insecticides can be applied
to the borders if parasites are absent. One estimate indicated a 9% loss
due to stink bug in Kona. Damage in the Hilo area is insignificant.
Recent observations
suggest that stink bug adults could cause significant kernel injury.
Planting
New commercial orchards
should be planned as complete production systems. Among the considerations
which arise from present knowledge are:
Select cultivars (varieties)
which tend towards a short bearing season.Recent studies by Ito and Hamiltion
(CTAHR) showed that yields of "Keauhou" from a mixed planting averaged about
16 kg (35.2 lbs.) more per tree than from a pure block planting. Mixed orchard
nuts were larger, had more kernels and more oil. Consideration needs to
be given to include selections known to be good pollinators within each
field.Use cultivars which have an upright growth habit and can be grown
close together. Consider planting closer in rows while leaving sufficient
space between rows for spraying and harvesting equipment.Use cultivars which
have a high proportion of No. 1 nuts, thin shells, and other desirable characteristics.
Checking with your county
agent and most importantly with growers nearby will help you in deciding
what will succeed in your particular area.
A survey by Keeler (CTAHR)
showed extreme variation in yield ranging from as high as 300 lbs. in-shell
nuts per tree to nil. Estimated mean yield for trees spaced 30' x 30'(48
trees per acre) is 150 lbs. per tree (7,200 lbs/acre). Yields at Keaau Orchard,
for trees spaced 25' x 25' (70 trees per acre) on orchard closure and full
nutrition, averaged about 100 lbs. per tree (6,970 lbs/acre). Potential
yield will depend on the land quality, particularly with regard to available
moisture, nutrition and also on how reliable are the projections for increased
recovery.A figure commonly used is 5,200 lbs./acre and this may prove to
be the limit for poorer lands under current technology, with 7,000 lbs./acre
readily attainable on the better lands with the overall average somewhere
between. The state average for bearing orchards is 3100 lbs /acre.Since
macadamia starts producing in about six years, there is a long period of
negative cash flow. To alleviate this cash flow problem somewhat, it is
suggested that the initial planting density be increased from the conventional
48 trees per acre to a higher density. Since trees will be small initially,
more trees can be adequately supported on one acre. If more trees are available
to produce a few nuts, the total production per acre should be higher in
the early years.
As the orchard
matures, a systematic program of pruning and tree removal can be initiated
so that the per acre yield will be unchanged from the conventional planting
density of 48 trees per acre. The industry is trying densities of 70 and
95 trees per acre. High density plantings look promising. Higher yields
per acre are being realized. High density planting depends on low cost trees
for planting.
Processing
Increasing the kernel
recovery rate from in-shell nuts is important. However, this must be balanced
against increased cost of improved recovery. Recovery is not important per
se, but cost of producing a unit weight of kernel is. Improved recovery
does not necessarily mean lower cost.Improved processing systems with better
shell-kernel separators and better cracking method could increase the kernel
recovery rate to 35%. Recovery rate also depends on variety and moisture
level. Nuts sold by the farmer average 16% moisture or more. The current
drying process produces kernels with less than 1.5% moisture. Drier nuts
ar much more susceptible to mechanical damage more bits and chips and hence
lower recovery, therefore careful handling and transport during and after
drying is critical, (Cavaletto, 1986, Proc. HMNA 26). However more research
is needed damage occurring to nuts in-shell and after cracking.
The current estimated
kernel recovery rate is greater than 23% based on final product and 28%
based on bulk kernel sales as nuts from new cultivars beginning enter production.
Processing technology to increase the recovery rate to about 31% is available.Insect
infestation of stored kernels is a problem for some processors (Mitchell,
1985, Proc. HMNA 25). There is a need to look into the threat of stored
kernel insect pests being brought into the State with the importation of
nuts from overseas. Current DOA/PQ and USDA regulations need to be reviewed.
DOA/PQ currently has no inspection, treatment or certification program for
nuts or kernels imported for processing. Mauna Loa freezes imported kernels
in their containers on the mainland prior to shipment to Hawaii.
The industry sporadically
experiences a kernel bruise-browning problem. A CTAHR project supported
by Hatch funds revealed that the problem involves mechanical damage to in-shell
nuts at intermediate moisture content. It appears most serious on the cultivar
508 when the in-shell moisture content is between 10 and 14%. Cultivar differences
are likely.
Harvest interval (the
time the nuts are left on the ground) affects shelf-life of the final product.
A study conducted by industry found that after 6 weeks, quality and shelf-life
decreases. Maturity did affect shelf-life, although it affected quality.
A CTAHR project funded by a USDA section 406 grant which ends in 1988, is
examining this problem in greater depth.
A great deal is known
about quality control on the farm, but the necessary measures are not always
practiced. A special workshop was organized for Kona growers in 1986 by
CTAHR's Cooperative Extension Service and HMNA to discuss growers' practices.
However, it is up to the grower to put these quality control measures into
practice.
Several small, locally
developed processing systems are available and in use. These make small
farms more profitable, but the overall net impact these systems will have
on the industry is unknown. There may be more variation in kernel quality
with many small processors. Also, competition for the same markets may start
to occur because there will be more people marketing kernels.
CTAHR designed and constructed
prototype macadamia nut cracker capable of producing the optimal deformation
on all sizes of macadamia nut. This project funded by regional Hatch funds
has made progress in fracture control and flash drying to attain optimum
kernel and shell moisture to increase kernel recovery (Liang, 1984, Proc.
HMNA 24.)
The important
feature of the cracker is that the orientation of the nut during sizing
is maintained during the cracking operation. Recent research examined the
role of shell notching and freezing on recovery of whole kernels. Notching
reduced the force and the deformation required to achieve whole kernel recovery.
Percentage recovery as whole kernels increased from 28 to 42%, and percentage
of uncracked nuts decreased 14 to 6%.
Freezing increased
whole kernel recovery from 28 to 83%, half kernels were reduced from 46
to 7%, and uncracked nuts from 14 to 10%. Combining both processes increased
whole kernel recovery from 28 to 88%, reduced half kernels from 46 to 9%,
and decreased uncracked nuts from 14 to 2%. At the scale of the pilot operation,
the increase in energy consumption was offset by the increased value as
whole kernels (Jason C.S. Chon, 1987, M.S. thesis, Dept. of Biosystems Engineering,
CTAHR).
A semi-continuous
deep bed drying process of in-shell macadamia nuts was further enhanced
for industry adoption by the completion of research for a M.S.thesis in
Biosystems Engineering (CTAHR) by Suhas Mehra (undefended as of May, 1987).
The technique could dry nuts to a uniform desired moisture content independent
of bed cross-section area, and can potentially be completely automated.
Estimation of total timing time for a given lot can be accurately estimated
after ten hours of drying.
Floatation separation
using water or brine is used by several processors to separate highest quality
kernels from lower quality kernels and shell pieces. A dry kernel and shell
separation method is desirable to increase of processing, however funds
are lacking for this.
Extent of losses from
the stuck-kernel problem is unknown. This affects the recovery rate and
appearance of the end product. A few current cultivars have been examined
for kernel sticking and some differences were observed.
Rancid nuts cannot be
identified visually, and analytical methods have not been sensitive enough
to detect early signs during processing. A CTAHR project funded by a USDA
406 grant which unfortunately expires this year has made significant progress
in acquiring the equipment and developing the necessary methodology to detect
the problem at early stages.
While it is apparent
that tocopherol, a well-known antioxidant is present in only low levels
in macadamia, other potent antioxidants have been identified and appear
to vary by cultivar. An assessment of reduction in shelf-life as a result
of field and processing practices has begun under this project. This importance
of this research increases if the industry were to enter a period of high
inventory and low price brought about by increased production. Additional
funding will be necessary to complete this promising research.
Demand is increasing
for macadamia oil by the cosmetic industry, especially in Japan. MacFarms
is investigating the development of a oil pressing facility to handle immature
and culled nuts, brokens, and fines. Value-added is increased substantially
if oil can be pressed, partially refined and sold directly to a cosmetic
company. The press cake would have value as animal feed.
Amendments to Chapter
4-44, Administrative Rules, "Standards for Fresh Fruits and Vegetables"
and Chapter 4-44, Administrative Rules, "Standards for Processed Products"
became effective August 18, 1983. These amendments were developed in cooperation
with the Macadamia Nut Industry Standards Committee and brought the standards
for the in-shell, shelled and roasted macadamia nuts up to current market
requirements. Subsequent to these amendments, the industry requested that
consumer grades for in-shell and shelled macadamia nuts be established.
The consumer grades became effective January 16, 1984.
The grading procedures
for shelled and in-shell macadamia nuts will be further refined in April
1987 and all inspectors trained in the new procedures in Fiscal Year 1986-87.
The grading procedures for roasted macadamia nuts will be further refined
in Fiscal Year 1987-88 followed by training of all inspectors.
Moisture balances are
now available in both East and West Hawaii districts. Effective January
1,1984, the Kona Coffee Technician has been upgraded to an Agricultural
Commodities Aid II whose duties include macadamia nut certification and
enforcement. The program's proposed Fiscal Year 1988-1989 budget include
funding for an additional Agricultural Commodities Marketing Specialist
for Kona.
Consumers perceive that
some manufacturers intentionally or unintentionally deceive the public by
implying that a product contains more macadamia nuts than is actually present
or that the shape of the package implies more product for less cost.
Propagation
Large commercial fruit
nurseries are uncommon in Hawaii owing to relatively small size of our industries
and longevity of crops. However in most areas there are nurserymen who will
do contract propagtion. Check with neighbor growers, HMNA representative,
or extension agent.
Remember, grafted
macadamia do not ship well. Survival after an interisland journey may not
be satisfactory.
Actual experience
with macadamias is usually essential for grafting success because the wood
is exceptionally hard and brittle. Scion-wood should be girdled at least
5 weeks in advance to accumulate starch a for successful grafts. Whether
or not sufficient time has elapsed can be tested by observing if a strong
starch (blue-black color) reaction occurs when dilute tincture of iodine
or water solution of potassium iodide is applied to a freshly cut surface
of the scion wood above the girdle. Without sufficient starch reserves,
the graft will not take.
Work is needed to develop
more asexual propagation methods for macadamia. Some work done in Hawaii
and Rhodesia has shown that macadamia cuttings can be made to root. The
results of the work done in Hawaii have not been published. However, the
root system of trees propagated in this way are weak and susceptible to
blow-downs. This has been shown in a test planting at Keaau Orchard and
an experiment at Waiakea (unpublished). Seedling rootstocks were always
more vigorous than the rooted cuttings tried.
Experimentation on the
mass propagation of desirable cultivars by tissue culture was conducted
by T. Matsumoto Nursery. This research was funded by the Dept. of Research
and Development, County of Hawaii and HMNA. The culturing was successful,
but plants have not been established under field conditions yet. However,
the economics of this method over the present method of grafting is still
under investigation.
Research in Israel demonstrates
that macadamia can be propagated from air layers. Plants propagated in this
manner bearing several years earlier that grafted plants. Resistance to
wind damage has not been determined in Israel. A field experiment is underway
to air layer plants in Hawaii and to determine its potential.
Do not use trees on
rough-shell ( tetraphylla rootstocks). Rough-shell seedlings are sometimes
preferred by nurserymen because they germinate uniformly, grow faster and
more uniformly in the nursery, and are considered somewhat easier to graft
and transplant. However, the trunk of smooth-shell varieties sometimes grows
faster and increases in diameter more rapidly than the rough-shell rootstock.
When this occurs, the trunk just above the graft union becomes larger and
thicker than the rootstock section below the graft union. This problem,
known as scion overgrowth, is considered undesirable in orchard trees and
should be avoided. Fortunately, it rarely occurs when smooth-shell varieties
are grafted on smooth-shell seedling.
Punch budding is a propagation
technique used in Australia which appears to be more efficient than the
wedge-grafting technique used in Hawaii. Less scionwood is required in punch
budding, which is a major advantage when trying to propagate large quantities
of limited materials. Preliminary trials on punch budding in Hawaii gave
less than satisfactory results.
Pruning
Pruning is essentially
limited to developing a conical tree shape with strong scaffold limbs in
the first two years following transplanting in the orchard. The reason for
pruning is to encourage maximium production and reduce susceptibility to
wind damage. The objective is to leave three branches at a node (whorl)
with wide angles from a single leader. Another whorl of 3 branches should
be left one and half to two feet above, so that these do not interfere with
the branches below. Some cultivars like 344 and 660 produce this shape with
little pruning.
If too many branches
emerge at a whorl, prune (thin out) to three.
If two or more
vertical stems (leaders) are present, prune to only one.
If a young tree
produces only vertical growth without branching, prune (head back) at 3
to 4 feet, select a new vertical bracnch as the leader, and prune others
to leave 3 branches with wide angles as scaffolds.
If root or trunk suckers
grow from the rootstock, remove them.
Public Policies and Regulations
OSHA, EPA, etc., have
many policies and regulations that affect the macadamia nut industry. The
public policies and regulations that affect the industry should be complied
and updated periodically. Policies affecting importation of agricultural
commodities affecting marketing competition would be monitored by DOA Marketing
and Consumer Services Division. Importation of insect or disease contaminated
produce would fall under the jurisdiction of the USDA and/or DOA Plant Quarantine
Branch of the Plant Industry Division.
The industry is concerned
that the importation of macadamia plants, and nuts for planting and nuts
for processing lead to the introduction of macadamia pests to Hawaii.
Current DOA/PQ and USDA
regulations need to be reviewed, as no special regulations exist regarding
importation of macadamia plants or seed. DOA/PQ merely requires inspection
of macadamia materials imported for planting. Regulations are also lacking
for nuts or kernels imported for processing. As a precaution against importing
pests, Mauna Loa freezes imported kernels on the mainland prior to shipping
them to Hawaii.
All pesticides are coming
under close scrutiny by regulatory agencies. Two pesticides registered for
macadamia though infrequently used, Difolatan and Plictran, fungicide and
miticide respectively, have been banned. Atrazine, a commonly used preemergence
herbicide, may be banned. Agricultural organizations individually and collectively
must work to maintain a public dialogue on pesticide use. Laws governing
the use of pesticides should be based on a rational approach and cost/budget
ratios. A crop loss assessment program is one approach that can be initiated
to examine damage and to determine economic value of losses address these
issues and to develop feasible and socially acceptable solutions.
Water
If macadamia is grown
on porous a'a type soil, at least 80-100 inches of rainfall is required.If
macadamia is grown on soil, at least 60 inches of rainfall is required.If
rainfall is insufficient, irrigation would be required. Whether macadamia
is grown in regular soil or a'a type soil, the trees should receive about
0.20 inch of water per day from rainfall and/or irrigation (5,500 gal./acre/day).Lack
of adequate water is depressing growth and yield in some areas, particularly
south Kona. These areas would benefit greatly if water sources were developed
to allow irrigation.Mauna Loa Macadamia Nut Corporation is developing its
own water sources and irrigation facilities in Kau.In Kona, growers who
use municipal water for irrigation have to pay $0.65 per 1,000 gal. This
rate is based on agricultural use.The State has recently completed the drilling
and testing of an exploratory well on State land in South Kona near Honomalino
at an elevation of 849 feet. Results indicate the well can produce 750 gallons
per minute of brackish water (800 ppm chloride). A great deal of the arid,
low elevation belt of the Big Island has ground water that is not potable,
but may be sufficient quality for irrigation. There are large abandoned
areas in Honomalino which may be revived by irrigation.
CTAHR and Farms
of Kapua are cooperating to determine the field tolerance to salinity of
the cultivars '344' and '800'. Trees are grown under an irrigation scheme
with rainfall only, and water concentrations of 0, 500, and 1200 ppm salt
applied at a rate of 80% of rainfall-adjusted evapotranspiration.
MacFarms plans to drill
a well mauka of the State well in Honomalino to irrigate its lower orchards.A
cooperative irrigation experiment between Mac Farms of Hawaii and CTAHR
was conducted on Mac Farms' orchard, and the results report by Foss (1986,
Proc. HMNA 26). The experiment was installed in an area (lower elevation)
which receives insufficient rainfall. Water is being applied through a micro-jet
system at 6 different rates (4, 8, 12, 16, 20, and 24 gals. per tree per
day) with adjustments being made for rainfall. Average cumulative yield
increase over unirrigated trees for two cultivars over 6 years at 1200'
altitude was almost 60%. At 1700' (higher rainfall) the yield improvement
was 8 to 10%. Effects of irrigation was reduced premature nut drop and greater
tree growth and hence bearing surface.The Hamakua agricultural water study,
which commenced in 1979, is now completed. The study:
Identified the agricultural
water and related land resource problems and concerns.Inventoried the study
area's resource base.Developed and evaluated alternative plans for alleviating
the agricultural water and related land resource problems.Selected a preferred
plan.Identified technical and financial assistance opportunities through
federal, state, and local agencies for implementation of the preferred plan.
USDA-SCS can be contacted
for details.
If irrigation water
is required, macadamia should be grown where water is available or where
the cost of pumping water will not be prohibitive. Wells in many areas have
highly saline water.
If 60 inches of rain
is adequate to support a crop, 30 inches of rainfall can support a field
with half the number of trees if water from the entire area is concentrated
in half the area. The region between Hawi and Mahukona is an ideal place
to test the idea of catchment irrigation. The region between Mahukona and
Kawaihae at elevations between 500 and 1,500 feet may also be suitable for
this type of farming.
|
