Stephen A. Hoying & Dr. Terence L. Robinson Cornell Cooperative Extension & Department of Horticultural
Sciences
The vertical axis planting system has recently generated
interest in the Northeast because of its high productivity, high fruit quality
and ease of management. Production can begin as early as the second leaf with
the ability to produce more than 1000 bushels of fruit per acre by the 6th
leaf. The fruit produced is of the highest quality with color, soluble solids,
and size all because of good light exposure throughout the tree. It is easy
and inexpensive to train and prune during the formative years. Our figures
show early training and pruning costs are about 25% of that of the Slender
Spindle at the same tree density and rootstock. At maturity, pruning is easy
and inexpensive, a fraction of the cost of a semi-dwarf Central Leader orchard.
Even though a trellis system is required to support the relatively tall narrow
tree form, it is easy to erect and of moderate cost.
This system originated in France and is now used throughout the world. It
and its variations are also known as the French Axe, Slender Pyramid, Triple
Axe, or just plain Axe. We believe that many of the training and pruning principles
gleaned from this system will become the important components of all orchards
in the future.
The Vertical Axis System is based on three principles...
Principle One
Rapidly grow the tree to approximately 10 feet in height by the end
of the third growing season.
This is accomplished by not heading the leader during
the development years thereby growing the tree tall very quickly and preventing
the development of strong upper tiers of scaffolds. The mature height of
the system is determined by the choice of variety, rootstock, support system,
and leader management. Mature height will rarely exceed 15 feet. In New York
and the Northeast, one of the M.9 clones or B.9 is ideal for most varieties
and gives a mature tree height of 10 - 12 feet. Weaker varieties can be grown
successfully on Interstem or M.26. When more vigorous stocks are combined
with vigorous varieties, trees are more difficult to manage.
It is necessary to install a support system soon
after planting. The preferred support system is simple, relatively inexpensive
and easy to install. Our recommended support system consists of a trellis
with a single high wire at 7.5 ft. The wire is supported by in-lines posts
(10 ft. long, 3/4 in. diameter) spaced
approximately 50 ft. apart and driven 30 inches into the ground. Anchor assemblies
at the ends of each row consist of an anchor post (4 - 5 in. diameter) driven
48 inches into the ground vertically and an angled (60º) inline post (3
- 4 in. diameter) driven 30 inches into the ground between the first and second
tree. The wire is attached to the bottom of the anchor post and run over the
top of the angled in-line posts and then down the row over the top of the vertical
inline posts. It is attached to each post with galvanized 3/4 inch 12 gauge
staples. Tension is maintained with wire tensioners in each row. Individual
tree support poles (either a 10 ft. 1/2" diameter galvanized metal conduit
or 10 ft. bamboo pole) are then placed by each tree and pushed into the ground
6 inches. The pole is attached to the wire and the trees are then attached
to the pole with a plastic tree tie.
Careful leader management in the formative years
is the key to making this a successful vertical axis tree. The leader is
not headed except at planting when necessary to establish permanent scaffolds
or balance the top with the root system. After this initial cut, the leader
is NEVER headed.
Vertical growth and early fruiting is maximized by not heading. It is important
to support the rapidly growing leader by fastening it to the support stake
as it grows. Rapid leader development and weak yet fruitful side branches are
encouraged along the leader by stunting competitive shoots using a technique
known as "Pinching". Pinching is simply the removal of the growing tip and
developing leaves of all competitive shoots sprouting within 12 inches of the
leader's terminal bud position at the start of the growing season. Pinching
starts when competitive shoots reach 4 - 6 inches in length and is repeated
as pinched shoots regrow more than 4 inches. Strongly growing varieties such
as Crispin or Gala must be pinched 2 or 3 times each year during the second
and third growing seasons. Weaker varieties such as Empire may only need to
be pinched once each year. Since pinching is only done from the ground and
by hand, it can cost as little as $10 per acre per trip.
Principle Two
Use a minimum of pruning during the formative years.
Training trees to the vertical axis is based on the principle
that no pruning results in greater flower bud formation and subsequent fruiting
while pruning stimulates vigor and reduces flowering. Like most other systems,
a minimum of four scaffolds is required. However, the more scaffolds the better.
Selected scaffolds should have good crotch angles and not be more than 1/2
the diameter of the leader. Starting in the second leaf, shoots that compete
with the leader are either removed or suppressed by pinching if they originate
within 12 inches of the leader. The lack of heading of the leader allows rapid
fruit bud formation along the leader. Vigor levels are easily managed in the
tops as long as no pruning cuts are made and early and heavy cropping occur.
The occasional strong competitive shoots missed during the pinching process
should be completely removed during dormant pruning. Permanent bottom tier
scaffold branches are spread or tied down during the second or third growing
season to produce calm fruitful scaffolds appropriate for the spacing. During
this formative period, it is important to spread and bend all vigorous growth
rather than prune. Training rather than pruning encourages rapid filling of
productive area and early fruiting. Early fruiting calms tree growth producing
a balance between vegetative growth and production.
It is important that the leader be permanently tied at the top of the support
stake to support the crop and maximize production. The leader is not pruned
during this stage. Tree height is limited by cropping which bends and bows
the leader above the support pole.
Principle Three
Renewal pruning of upper branches on mature trees will contain tree
size and maintain a conic shape.
As trees mature, lower tier scaffolds are gradually thinned to 4 or 5 with
proper vigor and position. Above that tier of scaffolds only smaller caliper
fruiting wood is allowed to remain in the tree. When branches exceed 1 inch
in diameter they are removed completely using a bevel cut. Latent or adventitious
buds from this small stub sprout, producing weaker fruitful wood in its place.
The leader is not pruned until fruit bends it over and weakens it. The weight
of the crop above the support pole is allowed to bend and in some cases even
break the leader before any pruning of the leader is done. This helps manage
tree vigor in the tree top. Then the leader is pruned to an appropriate upright
replacement. These fruitful branches in the upper half of the tree are only
shortened by pruning if it is necessary to remove pendant portions of the branch.
By following these three principles you will be able to
produce an orchard with tall narrow pillar-shaped tree with a strong dominant
trunk, a permanent lower tier of scaffold branches and only weak fruiting branches
arising from the trunk. The upper half of the tree will have virtually no permanent
wood. In contrast to the central leader tree training system it has no permanent
upper tiers of branches. These very narrow trees intercept nearly all the light
available to them yet their narrow conic shape allows good light exposure even
in the center of the canopy. The abundance of light ensures the production
of healthy fruit buds, excellent fruit set, and near perfect fruit quality,
particularly color.
Simplified Training Recipe for the Vertical Axis
Apple Planting System
First Leaf
At Planting...
1. Adjust graft union to 3" above soil level, tamp
soil around roots.
2. Remove all scaffolds below 22" using a flush
cut.
3. Trees with less than 3 feathers should be headed
at 32" and all feathers
removed using a bevel cut.
4. Trees with 3 or more scaffolds (10" long) should be headed 12" above
the uppermost scaffold with all scaffolds headed by removing 1/3 their length.
Soon After Planting...
1. Install tree support system that will allow tree to be supported to 10
ft.
2. Attach tree to support system with a permanent
tree tie above 1st tier of scaffolds leaving a 2" diameter loop to allow
for trunk growth.
1/4 - 1 inch Growth...
1. Rub off 2nd & 3rd buds below the chosen leader
bud to eliminate competitors to the leader shoot.
2. Deflower tree.
2 - 4 inch Growth...
1. Attach clothespins to new side shoots to promote favorable crotch angles.
July...
1. Tie developing leader to support system with Max Tapener.
2. Remove clothespins.
Second Leaf
Dormant...
1. DO NOT HEAD THE LEADER OR PRUNE TREES.
2. If additional scaffolds are needed, score above appropriate trunk buds.
4 - 6 inch Growth...
1. Pinch lateral shoots in top 1/4 portion of last
year's leader growth removing the terminal bud and 4–5 expanding leaves of
the lateral shoot.
June 15...
1. Re-pinch all lateral shoots in top 1/4 of last year's
growth.
2. Tie developing leader to support system with Max Tapener.
3. Remove all fruit on 1 year old wood and hand
thin remaining fruits to 6" apart.
Mid July...
1. Re-pinch vigorous lateral shoots in top 1/4 of last
year's growth.
2. Tie to leader support system with a permanent tree tie at 6' height and
tie developing leader to support system with Max Tapener.
3. Tie down 4 - 5 permanent lower scaffold branches
to the horizontal.
4. Position other vigorous upright shoots below the horizontal.
Third Leaf
Dormant...
1. DO NOT HEAD THE LEADER.
2. Tie down vigorous, upright limbs below the horizontal overlooked during
second summer.
4 - 6 inch Growth...
1. Pinch lateral shoots in top 1/4 portion of last
year's leader growth removing the terminal bud and 4 - 5 leaves of the lateral
shoot.
June 15...
1. Re-pinch all lateral shoots in top 1/4 of last year's
growth.
2. Tie developing leader to support system with Max Tapener.
3. Hand thin to single fruits spaced 4" apart.
Mid July...
1. Re-pinch vigorous lateral shoots in top 1/4 of last
year's growth.
2. Tie leader to support system with a permanent tree tie at 8' height and
tie developing leader to support system with Max Tapener.
3. Position other vigorous upright shoots below horizontal with elastics,
weights, tape, or string.
August...
1. Tie up lower scaffolds not expected to support the crop. Alternatively,
do not tie up but prune back scaffolds to prevent limb breakage, and preserve
tree structure.
Fourth Leaf
Dormant...
1. DO NOT HEAD THE LEADER.
2. Remove limbs that are overly vigorous.
July...
1. Position vigorous upright limbs below the horizontal with elastics, weights,
tape, or string.
2. Tie leader to support system with a permanent tie at the top of the pole.
August...
1. Lightly summer prune to encourage light penetration and maintain pyramidal
tree shape.
Fifth & Sixth Leaf
Dormant...
1. DO NOT HEAD THE LEADER.
2. Shorten bottom tier scaffolds where needed back to side branch to facilitate
movement of equipment and preserve fruit quality on lower limbs.
3. In each year, remove one of the least desirable lower tier scaffold branches
until only 4 remain.
4. Shorten branches that have become pendant back to horizontal portion of
the branch.
5. Remove up to one vigorous upper scaffold limb each year to begin renewal
of fruiting branches.
August...
1. Summer prune as necessary to maintain pyramidal tree shape.
Seventh Through Twentieth Leaf
Dormant...
1. Shorten bottom tier scaffolds by pruning back to side branch to facilitate
equipment movement and preserve fruit quality on lower limbs.
2. Remove and renew 1 - 2 vigorous upper scaffold
limbs each year preserving all weak fruiting wood and permanent lower tier
scaffolds.
3. Shorten leader down to desired height by cutting to a fruitful side branch.
August...
1. Summer prune as necessary to maintain pyramidal tree shape and encourage
light penetration.
