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

take place throughout the year, and nut season is
year-round. 'Kakea' (HAES 508) especially shows
this characteristic. Depending on the variety and
climatic conditions, Jones and Shaw (30) report
that nuts on the tree are mature approximately 215
days after anthesis (flowering). Although the nuts
are mature on the trees, field experience has shown
that they do not begin dropping until eight or
nine months after anthesis. Further maturity
research is indicated here.
Harvesting
Harvesting can be the single most expensive
operation, since large losses, especially in nut
quality reduction, can result from improper harvesting
method or scheduling. Except in mechanical
tree shaking, mature nuts drop off the tree and
remain on the ground until picked up by machine
or by hand. While on the ground, the nuts can be
eaten by rats, or they can become moldy through
minute cracks in the nutshell or a faulty formation
at the nut micropyle. Either way the losses can be
substantial. Consequently, the nut harvesting
schedule has to be rigidly maintained and followed
in any given area. The rat population, leaves and
other debris under the tree, periodic rainfall pat-
tern, air movement through the field, sunlight
penetration under the tree, and the general humidity
in the orchard should be considered in determining
intervals of harvest. Generally, an interval
approaching four weeks is a good point to start
from to work toward shortening or lengthening
the period to suit the conditions of the area.
In hand harvesting, nuts are picked up in
buckets, temporarily stored in bags, and loaded on
trailers or trucks to be hauled to the husking stations.
The bulk of hand harvesting is done by hired
labor or by contract labor on a per-bag cost basis.
Mechanical harvesting off the ground is practiced
by large growers using three separa te machines:
a leaf blower (Fig. 78), a nut sweeper (Fig.
79), and a harvester (Fig. 80). In mechanical harvesting,
after the area is blown clear of leaves and
debris, the sweeper brushes the nuts into windrows
between two rows of trees for the pickup harvester,
which is a machine with rubber finger scrolls to
kick the nuts onto a cross conveyor belt, which, in
turn, empties the nuts onto a lift conveyor to be
elevated and finally dumped into a towed trailer.
A new model of this harvester uses two synchronized
high-velocity rotation reels to eliminate
twig and leaf uptake.
Figure 78. Self-propelled blower to rid the field of leaves before sweep harvesting.
59