Agriculture Reference
In-Depth Information
Present-day blueberry harvester
Rotary picking mechanism principle
FIGURE 7.14
BEI blueberry harvester with a rotary picking head.
7.3.5 T
REE
C
ROP
H
ARVESTING
Development of harvesting mechanization in tree crops began in 1970 in apples, vari-
ous citrus varieties, peaches, and almonds. Tree crops represent the highest harvesting
zone, which suggests the greatest complexity. Similar to bush crops, commercially
available harvesters in tree crops use some form of mechanical shaking to detach the
fruit from the tree. Brown (2002) described the different mechanical harvesters devel-
oped for the Florida citrus juice industry. These harvesters are outcomes of a pro-
gram funded by Florida growers to develop new harvesting technologies to compete
in global trade markets. All of these harvesters used the principle of mechanical shak-
ing: (1) area canopy shake to the ground, (2) canopy pull and catch, (3) trunk shake to
the ground, (4) trunk shake and catch, (5) continuous shake and catch, (6) continuous
canopy shake to the ground, and (7) continuous air shake to the ground.
Out of these seven systems, three concepts emerged as having the most promise.
The first system consisted of two synchronous vehicles, one of which is equipped with
an oscillating trunk clamping system to shake the whole tree similar to nut harvest-
ing trunk shakers. Both vehicles had catch frames that formed a seal around the base
of the tree and caught the falling fruit as shown in Figure 7.15a (Futch and Roka,
2005a). Although this system was very effective in harvesting citrus, it suffered from
two major limitations. First, since each tree had to be individually grabbed and shaken,
the machine would have to come to a complete stop at each tree, which significantly
reduced the harvesting throughput. The other limitation was grower concerns associ-
ated with bark damage and frequent root unearthing, and although these issues were
later shown to have no long-term negative consequences on tree health or yield, these
problems significantly impacted the trunk shakers' commercial appeal.
The continuous canopy shaking approach was implemented in two scenarios
each using a similar rotating finger drum approach to harvest the fruit. The first
approach was a tractor-drawn system that could continuously run without stopping.
This approach, as shown in Figure 7.15b, was inexpensive and had a relatively high
harvesting throughput. However, it depended on an independent operation to pick
up the fruit. Fruit pickup created additional cost and, more importantly, introduced
concerns about pickup debris and rotten fruit, as well as concerns over bacterial
