Horticultural Considerations
Previous horticulture conditions for planting trees in the field were not suitable for mechanical harvesting. The high density of today’s grove design, combined with tree architecture, makes mechanical harvesting difficult. Trees intended for mechanical harvest require long trunk sections to prevent limb removal of fruit-bearing branches near the ground; therefore, the skirt must be higher than the historically planted trees. This setup prevents low-hanging branches from obstructing the trunk-shaking machines and the catch frames that collect the fruit when shaken from the tree. A successful mechanical harvest implementation requires a grove design that can identify the most efficient system for removing fruit from the tree. Tests were conducted on production systems that were not currently available in commercial groves, including high-density plantings of up to 545 trees per acre, grown under intensive irrigation and fertilization programs to develop the plants as quickly as possible.
The loss of trees in the 1980s due to citrus canker changed how nurseries and production practices operated, as new trees had to be planted and replanted in large blocks. This led to uniform plantings, which, combined with high-headed trees suitable for mechanical harvesting, could help growers reduce harvesting costs. Current nursery practices for HLB-affected trees are slightly different, as budwood must be certified and grafted onto greenhouses that are closed, and no high-headed trees are being produced since the disease was first detected in the state.
The use of chemicals to loosen the fruit from the tree branch was also a technique developed to make mechanical harvesting easier. Since the tree is shaken either by individual flaps or by an entire belt around the trunk, the goal is to use the least effort to detach the fruit, ensuring a uniform harvest. Today, HLB-affected trees often experience a high rate of fruit drop before harvesting due to changes in their physiological and metabolic processes. Additionally, the low root volume and reduced anchorage of infected trees are important factors, as trees are shaken during mechanical harvesting, and sudden root exposure can further damage the infected trees.
Additional Resources
High Headed Nursery Trees: Preparing for the Future of Mechanical Harvesting
- Originally published June 2006
- Reviewed September 2025; the information has the potential to be implemented in CUPS
Mechanical Harvesting: What about Tree Health?
- Originally presented December 2009
- Reviewed September 2025
Post Mechanical Harvesting Production Practices
- Reviewed September 2025
The shape of nursery trees in the future to improve mechanical harvesting efficiency
- Originally presented April 2006
- Reviewed September 2025