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

Figure 81. Shake harvester with catchment frames on two separate units working together.
Many types of harvesting machines presently
on the market can be adapted to macadamia nuts.
However, in the use of this method on lava land,
the orchard floor terrain must be improved with
fill materials (e.g., sand, quarry waste), making the
surface crevice-free to enable easier and more efficient
pickup of nuts. On a better type of soil, such
treatment is not necessary. The area under the
tree must also be kept free of weeds and leaves so
the nuts are not lost.
Prior to harvesting, small growers remove leaves
under the tree by blowing with a knapsack-type
blower. The leaves are easily separated from the
nuts in blowing since their light weight and flat
shape enable them to be blown further away. The
nuts thus exposed can be picked up by hand.
Leaves can also be eliminated in the orchard by
burning them in open areas among the trees, by
shredding and using them for mulch, or by baling
them for use as a biomass energy source.
Tree harvesting using vibratory machines is
being done by two large growers. One grower uses
a unit with two self-propelled machines with catchment
frames mounted on each unit and a grabshaker
on one (Fig. 81). This harvester has a shaker
clamp that hydraulically grips the tree trunk about
2 feet above the ground and vibrates the tree for a
few seconds to shake the nuts onto its deflectors
and the catchment frame. The nuts are then conveyed
to a bin. When filled, each bin is removed by
a high-lift tractor and replaced by an empty bin. A
shaker with its own catchment frame is now being
used with increased efficiency (Fig. 82).
Although tree harvesting has definite advantages,
the effects of this method on nut maturity (7),
quality, and yield (47) for all the cultivars now
being used in industry have not been fully demonstrated.
But labor availability and cost dictate
the adoption and perfection of this method as soon
as possible. Basically, the issue is whether the business
loss is greater when harvestable nuts are lefL
on the ground to become moldy or ea ten by ra ts
prior to harvest, or when immature nuts are tree
harvested, thus lowering nut quality. These business
alternatives may have to be decided on a
plantation-by-plantation basis rather than an
industrywide basis.
Several other methods of harvesting have been
tried experimentally through the years but discarded
because of some bad features in the methods.
A modified golf ball picker with spring-loaded
rollers about 2 feet in diameter was used and discarded
because it was too flimsy in construction,
and improvements appeared remote. A nut
sweeper with many brush units operating on the
main axis, so that each unit could follow its own
land terrain, worked well, but the project was
abandoned because of a drop in interest. Harvesting
using the vacuum principle has not been
too successful on aa lava land since the suction
created by the machine picked up all materials on
the ground, including nuts, smaller rocks, and
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