Additionally, fresh fruit packers and processors are focused on meeting consumers' expectations for popular new varieties. Consequently, our tree fruit team is focused on increasing orchard labor efficiency and grower profitability through research and extension outreach on efficient orchard production systems coupled with innovations in technology and practices.
Intensive orchard plantings on size-controlling rootstocks are a central tenet of orchard efficiency, including labor efficiency. While it is well known and generally agreed that smaller trees require less labor because they require less pruning and minimize ladder use, few high density training systems were developed with labor efficiency in mind and fewer still specifically to facilitate the use of labor-saving mechanization.
Intensive Apple Growing Systems and Efficiencies
During a series of intensive fruit production workshops designed to help growers transition to more efficient growing systems, we identified the following as the underlying key components--"blueprint"--of a successful intensive apple system:
- Size controlling rootstocks and tree density between 518 (6 by 14 feet) and 1320 (3 by 11 feet) trees per acre Quality nursery stock
- Supported canopies to maintain consistent canopy shape and position
- Single rows of tall narrow canopies ("tree wall")
- Canopy shape that complements natural tree form
- Minimal pruning and branching structure
- Simplified pruning and training tasks
Planting dwarf apple trees and adopting practices such as minimal pruning and simplified training is a key step toward labor efficiency. Older training systems that were designed to facilitate mechanization, such as the Tatura trellis, were developed to facilitate shake-and-catch harvest, but this method was abandoned by engineers for use on large-fruited species such as apple and peach because it results in unacceptable levels of bruising. Other systems were developed to create pedestrian orchards for labor efficiency, such as the Penn State Low Trellis Hedgerow and the Dutch Spindle. These training systems failed to catch on because tree training was intensive and required skill, and the extreme pruning and horizontal bending necessary for restricting canopy height often led to excessive vegetative growth and shading. In order to be economically productive, the orchard needs to achieve high light interception without creating dense areas in the canopy. Over time horticulturists found that when an orchard system is entirely within the reach of a person on the ground one of two bad things happens. Either
- the canopy is productive but too dense, causing a loss of fruit quality
- the canopy is too small, causing loss of yield.
The solution has been to increase canopy volume without condensing the canopy by growing the tree taller, while keeping it narrow and orienting the rows in a north-south direction wherever possible to minimize cross-row shading. On-going research on labor platforms has been useful to confirm that the following orchard system parameters facilitate mechanically-assisted labor and video sensing of fruit:
- narrow continuous tree walls, 3 to 4 ft. wide and 10 to 14 ft. tall and
- rows spaced no more than 14 ft. apart.
With orchard systems that create a narrow fruiting wall, we achieve both horticultural and technological compatibility. The biological efficiency of the tall narrow tree wall surpasses the performance of most existing systems. With 3 ft. wide canopies, both light distribution and platform labor reach are addressed simultaneously. Ladder use can be eliminated with platform adoption. Close spacing in the row creates a tree wall that is readily identified by self-steering mechanisms, and sensor technology mounted on robotic platforms. In-row spacing of 3 to 4 ft. increases early yields, benefits labor efficiency by assuring a continuous flow of work and permits simplified pruning decisions based on limb size.
Apple System Accomplishments
The aim of a Penn State NRCS Conservation Innovation Grant (CIG) project has been to develop growing systems and technologies that will allow greater mechanization and labor efficiency in the short term and fully automated systems in the future.
In twelve 1-acre model CIG plantings we are evaluating the effect of two high density apple growing systems on productivity, fruit quality and labor efficiency. These training systems utilize the same support system, and trees are planted at the same spacing (691 trees per acre). Two popular varieties, one with high vigor (Cameo) and one with low vigor (Honeycrisp), are being used to determine if a difference in tree vigor level influences the performance of these systems based on fruit quality and labor efficiency. The trees are being trained to form either a continuous tree wall, or as cone-shaped canopies with discrete gaps in the tree tops. Results to date indicate that neither yield nor sunlight will be reduced by training the top of cone-shaped trees to a continuous palmette, provided the width is maintained at ~60 cm. The large number of CIG trials and the relatively large size of the plantings also have provided adequate space for evaluating labor saving technologies developed through three USDA Specialty Crop Initiative projects. Gains in efficiency range from 25% for peach thinning to 105% for pheromone dispenser placement.
Critical to the creation of an orchard blueprint is the selection of the cultivar and the rootstock. In recent years new cultivars such as Gala and Honeycrisp have become more prominent in the fresh market industry. Not all may be suitable in all regions. Many of these cultivars are coming from European breeding programs and their performance is unknown in the United States. Increased emphasis is being placed on resistance to insect and disease pressures. Similarly, new rootstock candidates have been developed that allow for better tree efficiency, controlled tree size and resistance to diseases such as fire blight and insects such as woolly apple aphid. NC-140 regional research trial plots established at Penn State have provided uniform testing to evaluate attributes of a number of promising rootstocks.
Intensive Peach Growing Systems and Efficiencies
Peach production systems have remained largely unchanged for generations, due to the lack of tree size control and large labor requirements. The lack of dwarfing rootstocks for peach limits the extent of orchard intensification. The need to hand thin and to make multiple harvests makes working on tall peach plantings from ladders costly. Since 2007, we have evaluated new production systems that improve both productivity and labor efficiency. Since we do not yet have size-controlling rootstocks for peach, the intensive systems we have been evaluating have densities between 242 to 483 trees per acre. Our prior research demonstrated that the 18- to 20-foot row spacing common to perpendicular V peach plantings is also applicable to mechanical labor platform use.
Peach System Accomplishments
The peach systems trial has shown strong differences in yield and fruit size between systems. Yield per acre has followed this trend: Quad V (7 ft. row spacing) > Hex V (10 ft.) > Perpendicular V (6 ft.)> Open Center (14 ft.). The moderate density systems were the most productive for the first eight years of the planting because these systems produce more bearing surface per acre than the Perpendicular V and they fill their space much faster than the Open Center. While all three V systems in our study produced more small sized fruit than the Open Center trees, the Quad V and Hex V also produced more 2 ¾ inch and 3 inch fruit than the Open Center. Closely planted V systems can produce a large crop of large fruit if good management practices are applied.
With the development of mechanical blossom thinning and mechanized labor platforms, the labor efficiency in tall tree systems can be greatly improved. The results of this study show that a change in peach orchard training systems is overdue. Hex V and Quad V are productive, easy to train systems that create a narrow tree wall. These systems greatly facilitate the use of mechanical blossom thinning, as well as use of mobile labor platforms.
On-Going Apple and Peach Systems Trials
Currently under trial are four narrow wall apple training systems with Jonagold and Fuji. The systems are a Tall Spindle, Tall Trellis, Vertical Axe and Minimally Pruned. Yields, growth, fruit size and pruning labor are being measured. Apple rootstock trials include a planting of Fuji on 30 rootstocks--mostly advanced or released selections from the Cornell Geneva breeding program. A rootstock trial established in 2014 compares four Vineland rootstocks selected for cold hardiness, precocity and fire blight resistance and also the newest semidwarf Cornell Geneva rootstocks. Our research on peach systems has shown that Quad V systems have up to 85% greater annual yield and higher fruit quality than conventional vase systems, and that the narrow canopy of this system is more compatible with mechanization. New peach plantings have been established to determine if advanced tree training techniques and size controlling rootstocks can be employed to make such systems still more efficient and technology-friendly.
It is our hope that the results will continue to provide growers with regionally-adapted recommendations on growing systems for high yields of quality fruit, grown with the efficient use of labor and other inputs.
Team members: Jim Schupp, Edwin Winzeler, Tom Kon, Melanie Schupp, Tara Baugher, Rob Crassweller, Lynn Kime, Rich Marini