Pruning and training apple trees, basic principles and new strategies to
improve fruit quality in modern plantings . Why prune and train? An apple orchard is a
solar collector, fruit trees convert sunlight energy to chemical energy then
utilize this energy to manufacture a nutritious food. Apples. Before beginning work on the tree
architecture and in an orchard block, it is important to review why we prune and
train for trees. There are two main considerations, the total amount of light
intercepted, influences crop yield. And the distribution of light throughout the
canopy determines the location of fruit and its quality. The primary goal of pruning and training fruit trees is to improve sunlight distribution. Apple leaves almost harvest at least 30
percent of the sunlight available on a sunny day to operate at full capacity
and for fruit to obtain maximum size, color, and sugar levels. Where as with a
grain crop, 100% sunlight interception is optimal. With apple trees, fruit quality
must be balanced with total crop yield. Optimal sunlight interceptions closer to
70 percent. In this way leaves throughout the canopy operate
with adequate light. Light can move about four feet into a tree canopy before it
becomes limiting. Strategic pruning and training create windows into tree
canopies to let sunlight in. This is an important step to grow big sweet apples
with attractive skin color. Other goals to consider are tree size control and
increased yeild efficiency. Crop load reduction, fruit spur renewal, improved air
movement and disease control, limb selection in positioning, shaping canopy
to desired form. First, controlling tree size and increasing yield efficiency.
Pruning is a dwarfing process and can be used to maintain a tree in its allotted
space in an orchard row, optimizing pounds of fruit per pounds wood equates
to optimum yield efficiency. Second, crop load reduction. Since an apple tree will usually set more fruit than it can support, partial crop thinning can be
accomplished by removal of fruit bearing surfaces. Third, fruit spur renewal. Fruit size and quality decline on old spurs purning stimulates new wood with young spurs. Next, improved air movement which
promotes better drying conditions and spray penetration. These help to reduce
damage caused by insects and disease. An open tree canopy is important
component of a successful integrated crop management program. Fifth, when selection in positioning
remove the damaged in diseased branches. Also limbs that are more than a half the
diameter of the truck at the point of attachment. These branches tend to shade
lower portions of the canopy, limbs with wide crouch angles have the best balance
between shoot growth and fruit production. Any final goal of pruning and training
apple trees is to shape the canopy to the desired tree form. In apple orchards trees
are trained to a conical or pyramid shape and most training systems. How we make the windows into a fruit
tree is important. It's essential to understand when to use various pruning
and training strategies. There are two types of pruning cuts,
heading and thining. A fruit tree will respond very differently to the different cuts.
With a heading cut the terminal portion of a branch, limb or shoot is removed. The main effects of the cut are, an increased number of shoots, increased length of shoots, more upright growth, reduced
numbers of fruit spurs, and a denser canopy with reduced light levels. Heading cuts
should be reserved for training young trees and for limb renewal on mature
trees. If there is a portion of a tree canopy where increased branching is
desired use a heading cut. To make a heading cut, position pruner blades at an
angle about a quarter inch above a bud position to grow in a desired direction.
Pruning tools should be kept sharp so that the cuts can be made quickly and
smoothly. One type of heading cut that should not
be used on apple trees is a bench cut. It is preferable to use training aids to
adjust lim angles. With the thinning cut an entire
branch, limb, or shoot is removed. Growth is stimulated at the site of the cut but
to a much lesser extent than with the heading cut. The main response is fewer
shoots which resulted in more open canopy and improved light distribution.
Thinning cuts are utilized in both young and mature trees to maximize light
interception, crop production, and fruit quality. To properly thin out a shoot make a
pruning cut at its base just outside the collar. Notice the swollen area. Keeping the color
intact will result in an improved healing response. To encourage the
development of a new branch at the site of the cut a bevel or dutch cut is used.
This is an angled cut that preserves the latent bud on an underside of the shoot
that will likely grow into a renewal one. Various training strategies can be used
to open windows and fruit tree canopies. The principal to keep in mind is that a
very upright shoot will tend to be overly vigorous and will not bear much
fruit creating poor light conditions. At the other extreme, a shoot or branch in a
flat orientation will produce an excessive number of fruit and shoot
growth will be minimal. The ideal branch angle various with apple variety and
training system but is generally between 50 to 75 degrees from vertical for
permanent scaffolds. A scaffold limb spread to a wide angle will have better
balance between vegetative growth and fruit production. Temporary branches in upper tiers of an
apple tree or train to horizontal positions to induce fruiting. A second
or third tier branch that is overly vigorous should be bent to below
horizontal. Popular training systems in newer orchard blocks for the vertical axis
and the state central leader, both used with size restricting rootstock. In older
blocks common systems are the freestanding central leader and the
multiple leader upside-down pyramid system. Pyramid or cone shaped trees either the
vertical axis or the central leader system intercept adequate sunlight while
allowing good light distribution to the lower canopy. An orchard of pyramid
shaped trees is arranged just like an efficient solar panel system, the top of
each panel allows light to reach the base of each panel. Large freestanding central leader train
trees and especially multiple leader train trees have poor light conditions
it is crucial to create windows of light by thinning out each scaffold in
relation to itself and to the others around it. Developing a pyramid-shaped canopy
requires patience, at some point as the tree reaches five to seven years of age, the leader will grow taller than planned
final height of the mature canopy. It then becomes a temptation to attempt to
contain tree height by shortening the leader, do not give in to the temptation,
wait until leader has become fruitful and its growth has slowed before heading
it. Often this will not occur until the 7th leaf. Then shorten the leader by
cutting back to a fruitful side branch. The leader must be allowed to grow
taller than the final tree height for a year or two. Cutting too soon will lead to
delayed fruiting and more vigorous re-growth, some refer to this management
technique as crop and flop. Pruning becomes more intensive with multiple leader trees. The greatest
challenge in this canopy shape is to prevent the upper branches with good
light exposure from outgrowing and shading lower limbs. Productivity and
fruit color in the lower canopy declined when this shading occurs. The most vigorous limbs in the top must be pruned out to maintain adequate light penetration in
the bottom of the canopy. Thinning cuts are preferable to heading or stubbing back
cuts. Sometimes multi leader trees are created unintentionally by leaving too
many permanent branches in the top of the canopy and letting these become too
dominant. This condition can be corrected by removing two to three major limbs per
year from the upper canopy over a three-year period. Dust converting the
canopy back into a conical form, yields are reduced during this period of
conversion so this technique is usually reserved for younger semi dwarf
trees. Pruning and training techniques vary with varieties of different growth
habits. Spurr type trees such as new delicious strains, tend to have fewer more
upright scaffled limbs and more friuting spurs compared to non spur varieties. The
limbs had minimal branching. In spur type apple blocks, a greater number of
permanent scaffleds can be selected and strategic heading cuts are warranted
when more shoot growth is needed. Various training aids can be used to bend
the limbs to more desirable orientation. Terminal bearing trees such as Rome and
Granny Smith tend to have weaving growth habits. Hanging limbs are removed with thinning cuts or stubbing cuts. The spurs are short shoots and for good productivity should not be
thinned too heavily, don't worry if terminal bearing trees do not look as pretty as
trees of other growth types when you're done pruning. Young terminal bears and
spur types both tend to a blind wood. Delaying pruning until late spring
will encourage more branching on blind shoots. Bearing apple trees may be pruned once
they have stopped growing for the season and after exposure to freezing
temperatures. pruning in late spring and induces more bud break, pruning after
bloom called the delayed dormant pruning is deenergizing and is a useful practice
on trees that are overly vigorous. Avoid pruning before a cold event, as pruning reduces
the trees hardiness for about 10 days. The greatest loss of hardiness is
within 48 hours of pruning, when the forecast indicates a potential drop to
about negative twenty degrees Fahrenheit or drop of more than 50 degrees and
inter negative numbers, stop pruning until the severe weather is past. Pruning is a
cumulative process apple trees really have perfect forms and you do not want
to remove every branch that is less than ideal. Prune only as much as needed consider, tree vigor, cropping, and natural
growth habit. On large trees you can make about three big cuts and remove up
to about a third of the smaller limbs. It takes about three years to do
corrective pruning on neglected trees. On narrow canopy trees
such as the vertical axis you can make about one large cut per season, this
should be a bevel or Dutch cut as described earlier for the purpose of
lim renewal. Although pruning is a dwarfing process,
it isn't a substitute for natural size control and should be used as an aid not
as a means of dwarfing. Avoid severe pruning bend a limb rather
than cut it out when possible. Trees that are prune to heavily will
have reduced cropping, excess wood production and will be less efficient.
On trees that seem to need heavy pruning save some cuts for next year
rather than sacrifice fruit yield. Modern orchard planning should be pruned carefully to maximize cropping and fruit
quality. Fortunately if you remember some basic pruning and training principles
and techniques you'll make a huge difference in the success of an orchard
operation. The main goal is to create windows to increase light distribution. Use thinning cuts in most situations. Reserve heading cuts for portions of the
canopy were increased branching is desired. Use a bevel or dutch cut for scaffold
renewal where a limb has become overly vigorous. Ideal angles for permanent
scaffold limbs are 50 to 75 degrees from vertical. Pyramid shaped trees intercept the most
sunlight maintain a tree structure that is wide at the base and narrow at the
top. With the heaviest diameter branches in the first whirl and the branch
diameter gradually decreasing in upper tiers. Avoid pruning before a cold event. Avoid severe pruning. Pruning is a cumulative process. Prune
only as much as needed. bending some limbs rather than removing
them, save some cuts for next year. You will take tremendous pride in apple
blocks you have handled in this manner. As your impact on the orchard enterprise
will be obvious. Apple trees will have better light quality, which will lead to
higher productivity and better fruit quality.
