Competitive Apple Orchard Training and Pruning Systems

by R. M. Crassweller and D. E. Smith
Penn State University

In the last ten years much has changed in the apple production system. Driven by the development of new varieties and the need to produce fruit early in the life of a planting when the returns for these news varieties are the highest; growers have altered their orchard designs. This presentation is meant to review some of the training systems evaluated in the past ten years and to look at some of the newest concepts in training systems. Some of these new systems and methods were recently presented at an international symposium held in Geneva, NY this past summer.

In the past the main concern when establishing a new orchard was to contain establishment costs as much as possible. Large free standing trees were the norm and production usually did not start until the fifth or sixth year. However, today new systems are going to be revenue driven rather than cost containment run. The higher the market value of the cultivar the potentially higher the density. At the higher densities tree cost may become important. Lastly, growers need to think creatively about their support system options.

Not too long ago planting densities of 200 to 300 trees per acre were considered intensive. However, now it is more common to see densities that are between 500 to 1,000 trees per acre. Some are even advocating 1,200 to 2,000 trees per acre. This latter density will largely depend upon the cost of nursery trees.
So how do we move from a lower density up to a higher density system? The answer to some extent depends upon the ability of the orchardist to manage their trees and having the capital to invest in the infrastructure needed for the support system.

Several years ago Matt Harsh and I developed a support system cost calculator for determining the money needed to pay for the trees and the support system. That spread sheet is available on the CD that came with your course materials. I recently went through the spread sheet and updated the prices based upon costs that I paid for support materials this past spring.

You can download the spread sheet from the CD onto your computer and enter your values to help determine the system best suited for you.

Data entry is pretty straight forward; you enter the tree spacing, row spacing, row length, number of wires and line pole spacing. The system will then calculate the feet of row per acre, trees per row, trees per acre and number of rows per acre. You can input values for all the hardware or use the figures supplied. The large table on the right shows how much hardware you need per acre and what the cost of the materials will be. This cost does not include costs needed to prepare the land, plant the trees or erect the support system since this will vary depending upon the scale of your operation and how much of the labor you provide or contract to hire.

Before we begin to look at new systems let’s review some of the tree training systems that require support that have been around for a few years. For the past 12 years I have been working on training systems here at Penn State. We had two plantings in Adams County utilizing York Imperial and a planting at Rock Springs utilizing Ginger Gold, Gala and Fuji. We kept detailed records on the yields from the time they came into bearing in their third leaf (1999) until their 10th growing season (2006). Again using a spread sheet that Matt Harsh developed based on work with commercial fruit growers we were able to track the cash flow return back on a per acre basis (This spread sheet is available on the Adams County Extension web site under Fruit Grower Resources). The first analysis we did was to compare the net cash flow return across systems using Fuji as the cultivar. Three points are important; first the Axe and the V-Axe were the most expensive systems to erect. In the V-Axe tree density was 50% greater than the standard Axe so tree costs were greater plus we needed the addition of a heavy cross bar to form a ‘T’. The Slender Spindle (SS) and Trellis (T) were less expensive because they did not require tall posts. The trellis was the cheapest because it was the only system that did not require individual tree stakes.
The second point in the cash flow analysis was that the T hit a net positive cash flow first at the fifth growing season. This meant that after this year all the money above annual operating expenses was profit. The VA and A did not clear a net positive cash flow until the 6th growing season.

The final point is the ultimate total cash flow at the end of the 10th growing season. The most profitable production system in terms of return on investment was the A system followed by the VA and then the SS system. The trellis system returned the least over the ten year period; most likely because of the smaller canopy volume due to height restrictions and spread restrictions. In fact, given the same canopy width but increasing the canopy height to nine feet did result similar yields. So the take home points are: an inexpensive support system does not always guarantee the highest profit and the number of trees per acre impacts the potential profit as well.

Another factor in the expense of high density systems is the need for individual tree support in the form of a stake or conduit. This lead us to try a new type of system this spring; a system composed of only wires with no conduit or stake for each tree. Using the support system cost spread sheet we calculated the difference between a 9’ tall support system consisting of 5 wires beginning at 2.5 feet and thereafter every 18 inches and a single wire with a conduit support for each tree. The 5 wire system for materials and trees cost almost $1,200 less per acre which was a good advantage. The only disadvantage to the system is that it is a trellis system and you cannot move through the row easily.

Nevertheless, there are many innovations that growers have adopted to reduce the cost of their support system while still growing taller trees. One grower, that was using metal stakes took extra stakes cut them in half and welded them on to the original stake in the planting. Others have fashioned Best Angle™ stakes or waste fiberglass tubes to the pressure treated posts.

There is no perfect system for all situations. Soil vigor, cultivar vigor, cultivar growth habit and site selection must all be considered when deciding on a production system. The horticultural skill of the grower, their workers and their ability to communicate proper instructions to those workers affect the success of any system.

Let’s look at some systems and point out their good and bad points. The first being the Slender Spindle. This system was developed in the early 1960’s by Wertheim in the Netherlands (Wertheim, 1968). The concept was to develop early yields with higher tree densities and reduced tree height to allow for more efficient management conducted from the ground. The tree is a narrow conic shaped tree with permanent lower scaffolds and weak semi-permanent upper scaffolds. Rootstocks used are predominantly M.9 but B.9 and possibly some of the new Geneva rootstocks might be used. The leader is headed and trained in a zig-zag fashion to reduce vigor. This system became the dominant system in many parts of Europe. Here in the U.S. it has been successful where soil vigor is low. In many PA orchards M.9 is too vigorous for this system.

In our trials, we were unable to maintain a true pedestrian orchard as the leaders tended to be too vigorous reaching heights of 9 to 10 feet. The result was an overly vigorous top that we continued to prune hard each year leading to more vigorous growth and subsequent shading in the lower portion of the canopy. The Slender Spindle as originally conceived has had a few new iterations and is a viable system when soils and cultivars have lower vigor and the growing season is shorter.

The next major training system, the French Axe, although introduced in the mid 1980’s did not really catch on until the mid 1990’s. This system, in one form or another, is probably the dominant training system for apples currently utilized. In the U.S. the most common modification to the original training system is the inclusion of a set of permanent bottom scaffold branches. In the original French version even the bottom scaffolds were renewed over time. I would encourage any of you that have not done so to go to the Rice Fruit Company web page and select the Links button to download a copy of the original bulletin about the design and training of the French Axe. This bulletin was translated from French by Mark Rice and is well worth reading.

The purpose of the vertical axe was to improve fruit quality by letting more light into the tree and reducing heavy dense canopies. The goal is to reduce the non-bearing time of the block and to simplify pruning and drastically reducing heading cuts. It is essential that a balance is achieved between vegetative growth and fruiting with fruit production acting as a control on tree vigor. Finally the system takes advantage of a cultivar’s natural tendency for producing fruit.
The basics to this system is beginning with a feathered tree, although you could use unbranched whips. The unbranched whip, however, will delay fruiting due to the need to head the tree to develop the scaffolds. Pruning in the first three years is minimized as much as possible. Scaffolds are trained to develop flat angels. If a feathered tree is planted then the leader is not headed, if there are too few feathers then the leader may be headed. It is imperative that the leader be secured to support as soon as possible to encourage upright vigorous growth. Beginning in the second year shoots that develop off of the leader above the main scaffolds are pinched back when still green and succulent during early June and July. This practice is continued as long as you can reach the developing shoots. Pinching can be accomplished either with shears or if done early enough just using your fingers. My preference is to use shears and do it a little later when there are more shoots. The leader is encouraged to grow upright and to fruit heavily causing the leader to “flop over”. This is the so-called ‘crop and flop’For more visuals there is a slide set on the internet that walks through the training procedures.

Occasionally some varieties will not “flop” or you may wish to ultimately limit the height of the trees. In order to do this you first need to let the top crop for at least one year and preferably two years. After this you can come in and undercut to a weaker side branch.

In a stylized drawing looking across the row you would see a ‘sawtooth’ appearance with teeth of light exposure in the tops of the trees. The view from the end would look typically as a triangular or pyramidal type tree. The new Conservation Innovation Grant plantings are a modification of the Axe system. The end view would still be the same but the across the row view will be decidedly different with a traditional bottom canopy extending into the drive row but the to being restricted to a flat palmette without the ‘teeth’ between trees. I am sure that Jim will discuss this a little bit more when he talks about the first year pruning.

We also had two York Imperial plantings in Adams County at commercial grower orchards. One was planted in 1997 with M.9 T337 as the rootstock and the other was planted in 1998 with B.9 as the rootstock. While the Axe was very productive the system that was the most productive was a modification of the Axe where after initial training to have horizontal main scaffolds and pinching of shoots above them for the first two years the trees were then minimally pruned in all subsequent years. Minimal pruning consisted of removing any broken branches or any vertical upright suckers and strong vigorous limbs growing back into the center of the tree. Since the variety was going to the processor we were not concerned about developing adequate fruit color.

For the York Imperial on M.9 the first year of cropping was the third leaf and yields in the 5th through the 8th leaf were above 600 bushels per acre and then jumped in the ninth and tenth leaf to over 1,000 bushels per acre. For the other planting established in 1998 again first yields were in the 3rd leaf. However, here the yields climbed much more rapidly and except for a frost in 2004 were at or above 1,000 bushels per acre. In conclusion with a processing cultivar where fruit color is not important, the minimally pruned trees were the most economical. It should be stressed that this system depends upon using good scaffold management techniques in the first two years to establish the wide angled scaffolds. From these two studies it is clear that a tall narrow canopy is the most productive currently utilized system.

Based on our studies and from work done in NY we started a new round of training system trials. This past spring we established a planting with four systems; a traditional Axe, Minimal Pruning and two new variations. One is what we are calling a Tall Trellis and the other is from work by Terence Robinson and is called a Tall Spindle. The tall trellis, is not necessarily new, but given the interest in the use of platforms as an assist for pruning, training, thinning and harvest may prove to be beneficial.

One of the problems we had with the low trellis was that we sacrificed bearing potential of a higher canopy in the taller systems. At the end of the 10th leaf we measured the canopy volume of the trellis and determined that fruiting density was similar for the Axe. Therefore if we would get the same fruiting density and increased tree height we should have an equivalent yield. A trellis provides a thin wall of foliage that produces better fruit color and is faster and easier to harvest.

The tall spindle as envisioned in New York is for densities of 850 to 1,400 trees per acre also using dwarfing rootstocks. This system has several important components. First the tree should be feathered and preferable highly feathered. Trees are not pruned or minimally pruned at planting. Limbs are bent below the horizontal. There are no permanent scaffolds and limb renewal is practiced on an annual basis once the tree begins cropping by removing limbs that are more than ½ diameter of the leader with a ‘Dutch cut.’ As shoots develop keep them singled down by removing any forks that develop.

It is based on the assumption that fruit are the best restrictions of vegetative growth. Cropping must begin in the second leaf with crop loads of 3-5 fruits per tree and increased each year based upon trunk diameter. Cropping levels are maintained at 3 to 5 fruit per centimeter of trunk cross sectional area.
Appreciation is expressed to Mr. Mark Bream and Mr. Brian Knouse for allowing us to utilize plantings at their farms for the study on York Imperial.

References

Clements, J. 2007. UMass video fruit advisor: Tall spindle apple planting. http://video.google.com/videosearch?rlz=1B3GGGL_enUS209US213&hl=en&q=Tall+Spindle&um=1&ie=UTF-8&sa=X&oi=video_result_group&resn

Hoying, S., T. Robinson, M. Fargione. The tall spindle planting system for apples in the Northeast http://www.ces.ncsu.edu/depts/hort/hil/pdf/hil-360.pdf

Parker, M. D. Unrath. 1998 High density apple orchard management techniques. http://www.ces.ncsu.edu/depts/hort/hil/hil-360.html

Robinson, T. L. Modern apple training systems. http://orchard.uvm.edu/uvmapple/hort/ROBINSON_ModernAppleTrainingSystemsVTFGAFeb2006.pdf

Robinson, T. L. 2008. UMass video fruit advisor: Four rules for pruning tall spindle apples. http://www.youtube.com/watch?v=ZqZPQV9l9jA

Wertheim, S. J. 1968. The Training of the Slender Spindle. Proefstation Fruiteelt, No. 37, Wilhelmindorp, The Netherlands. 37 pp.