by Tamara Scully
Row after row of wires stretch across the field, into the distant horizon. The wires run horizontally, forming a four-wire trellis, with the tallest wire at about 10 feet, the lowest around two feet off the ground. Thin, tall trees grow vertically in rows, spaced a mere few feet apart, with bent branches, sloping down towards the ground. Small fruits line the branches, hinting at the season’s yet-to-be apple crop.
“I really don’t know anything about growing apples,” said farmer Greg Donaldson, who is primarily a vegetable grower.
After years of turning away callers seeking to come to the farm in Warren County, New Jersey, for apple picking each fall, Donaldson decided that along with PYO strawberries, pumpkins and flowers, he needed to capitalize on the demand for apple picking. He planted the first of the tall spindle apple trees five years ago, because the pruning system looked simple enough, he wanted volume production as soon as possible, and he wanted fruit reachable for pick-your-own customers.
Win Cowgill, Rutgers Cooperative Extension Agent for Hunterdon County, New Jersey, and the Northern Region Fruit Specialist, is a big promoter of tall spindle apple trees. At the Snyder Research Farm, trees are trained to the similar super slender spindle system. These trees are even closer together than those planted at Donaldson Farms. The Snyder Farm’s trees are planted at a density of 1,742 trees per acre, and yielded 200 bushels of apples per acre a mere two years after being established in the orchard.
While trees grown in these closely spaced, vertical systems are known for high yields in short periods of time, they do require some special care to establish. In fact, the key to a productive tall spindle system begins with a better young tree, Cowgill said.
“If you plant just a whip, you have to grow branches the first year,” Cowgill said, but with a feathered young tree, the branches are already established, and the serious business of producing apples begins.
The trees Cowgill would like to see coming out of the nurseries would have a good amount of feathering, which can be promoted through the use of Maxcel, a chemical used to increase branching. By spraying the growing tip every two weeks, the nurseries would produce a nicely feathered young tree.
Cowgill also cautioned growers who want to try a tall spindle type system to custom order their trees several years ahead of planting. Getting the correct rootstock, and getting the best trees, not the grade-outs, can make a major difference in production, he said.
Establishing the system
In the tall spindle system, the leader is promoted, and is not pruned. Even if planting a whip, the leader should not be cut back, which will not promote the growth pattern needed for the system. The buds around the leader are removed, or any top shoots are cut back, to select for the leader’s growth. The leader should grow rapidly to the top of the trellis.
The feathers are bent below horizontal. The degree of branch angling depends upon the tree spacing in the row. Closer spaced systems require more bending than those spaced further apart. In these systems, the branches are not permanent, and any robust branches — those more than one-half the diameter of the trunk — are removed.
“You’ve got to spend some time with these young trees,” Cowgill said. The pruning is “diameter-based pruning,” and leaving big wood will “shut down the tree.”
Branches are bent down below horizontal, using clothes pins, clips or elastics. By doing so, the branch will develop buds, and bear fruit the next year. This should be completed by late spring. Subsequent pruning involves removing any large branches and clipping back side branches longer than a few inches, as well as keeping branches below horizontal. In this manner, the tree’s balance is repeatedly renewed with new, young branches, and the energy goes into fruit production.
The trees require regular water and fertilization. The increased feathering of the young trees requires more water, due to their large leaf area. Increased nitrogen to support growth in highly feathered young trees may be needed for the first three years.
Establishing a healthy growing environment prior to planting promotes the rapid leader growth needed for successful tall spindle production. The leader should be clipped to each wire as it reaches it. Clipping reduces movement. Movement of the tree promotes undesirable trunk thickening, and also utilizes energy better used in fruit production. So providing proper support early on is critical for retaining growth and productivity. Creating the environment where the leader can grow rapidly during the first three years, and reach the 10 foot trellis height, is important for future production.
When trees reach the top trellis, don’t just cut off the leader, Cowgill said. This would stimulate growth, and for about two feet below the cut, too many branches would be produced. The leader should be cut properly at about 12 feet.
“You always have to leave a wick. Always leave one apical bud a the top. You don’t just cut it off. Cut to always have a side shoot,” Cowgill cautioned.
The time to head the top of the tree has to do with the spacing between the rows, he said. When the tree is 9/10ths as tall as the row is wide, then you want to cut the top.
“If you let your trees get too tall, they’ll shade the bottom of the next row when the sun comes around.”
For a successful tall spindle system, cropping must begin the second year. The target is about 20 fruit per tree at that time.
The rootstock is important in this system, with the dwarfing M9 and B9 being favored for vigorous scion cultivars. For weaker scion cultivars, a more vigorous M9 rootstock may be warranted. The rootstock, the variety of apple and the soil fertility will all impact spacing in a tall spindle system.
Extensive pruning is not needed in mature plantings: the bulk of the pruning and training labor occurs in young trees. Once established, mature pruning is minimal, removing low hanging branches, shortening branches, and annually pruning two larger branches for limb renewal. Maintaining a columnar canopy, for best light penetration, is important.
At maturity, the trees will be about four feet wide on the bottom, tapering to a two-foot width near the top. The close spacing of the trees in rows creates a hedge effect, with the space between trees filled with short, fruiting branches. The design allows for easy access for orchard equipment, as well as the ability to easily pick the readily accessible fruit. While a tall spindle system requires more inputs — trellis wire, posts, supports, and clips — than a more traditional orchard system, the potential productivity per acre, as well as efficiency, in a high-density system is much greater.
Without requiring large amounts of ongoing labor at crucial times during the season, when energy needs to be spent on vegetable production, Donaldson Farms was able to provide its customers with a pick-your-own experience and fill a niche, adding an additional crop and activity to their farm market.
Tall spindle apple trees
by Tamara Scully