Agriculture Reference
In-Depth Information
removal for raspberries. The force required to remove the ripe fruit was measured,
and forces on the berries at different locations in the bush were evaluated. Results
showed that most of the fruits were removed by large forces. In addition, increasing
drum excitation frequency and stroke length of fingers increased the removal of both
ripe and unripe fruits. They concluded that poor performance in mechanical removal
can occur in (1) failure to remove all ripe fruit, (2) removal of unripe fruit, (3) spill-
age of fruit, and (4) damage to fruits and canes.
Peterson et al. (2003) investigated the feasibility to mechanically harvest eastern
thornless blackberry with fresh-market quality. The over-the-row harvester used a
direct-drive spiked drum shaker for the selective removal of fruit and energy-absorbing
catching conveyor to reduce impact damage (Figure 7.13). An internal conveyor
transferred the fruit to the manual sorters. A rotatable trellis was used to position
the fruiting canes in a harvestable position. Results showed that the harvester was
only able to harvest 40% of fresh-market quality berries. They concluded that it was
not feasible to harvest fresh-market quality blackberries unless several issues were
resolved such as uniform fruiting canopy and establishment of significant differ-
ences in detachment force between mature and immature berries.
Although it is a challenge to mechanically harvest berries for the fresh market,
most of the blueberries for processing are mechanically harvested. Figure 7.14 shows
a Blueberry Equipment Inc. (BEI) harvester. BEI is one of the pioneers of the devel-
opment of blueberry harvesters that started in the mid-1960s. This current blueberry
harvester is equipped with two rotary picking heads that have 288 nylon fingers.
These fingers vibrate and comb the bushes to detach the ripe fruits (BEI, 2009).
FIGURE 7.13
Mechanical harvester for the thornless blackberry for the fresh market. (From
Peterson, D.L. et al.,
Appl. Eng. Agric.
, 19, 5, 539-543, 2003. With permission.)
