Successful Pruning of Fruit Trees
While the principles of pruning fruit trees do not
change, the actual practices used in modern production systems vary. The
higher density-supported training systems now used by commercial growers
are managed by the same principles of pruning used in the past. Before
embarking on a specific training system for high-density plantings,
investigate specific techniques required for training and pruning that
Pruning Dwarfs Trees
Numerous experiments show that pruning is a dwarfing
process, that is, it reduces the total size of the tree. Leaves are the
food-manufacturing organs of the tree. Cutting away a live branch, which
if left would have borne leaves, reduces the output of the "factory",
and the final result is a reduced bearing area. Summer pruning has the
greatest dwarfing effect.
Pruning Appears to Invigorate Trees
There is a certain deception in the effects of pruning,
in that strong shoots with large leaves tend to rise just at the back of
pruning cuts. This gives the impression of increased growth. Pruning
reduces the number of growing points, thus stimulating an increase of
growth at the remaining points. However, pruning, in proportion to its
severity, reduces the total growth and the total leaf surface of the
tree. (Invigorate trees when necessary with appropriate fertilizer use.)
Pruning Effect is Localized
The removal or cutting-back of the laterals of a branch
reduces the growth of that branch. Pruning has the direct effect of
producing growth response in the immediate area in which the cut is
Pruning Too Heavily Has Several Ill Effects
Excessive pruning, by over-stimulating growth, causes
loss of fruit colour, delayed fruit maturity, and growth of suckers and
watersprouts. Excessive succulent growth increases the hazard of fire
blight in apple and pear, canker in peach, and winter injury in all
Pruning the Young Tree Delays Fruit Bearing
Because pruning tends to force the growth of long,
succulent shoots that grow late in the season, manufactured food is not
allowed to accumulate in sufficient quantities to cause the formation of
fruit buds. Consequently, the tree is kept in a juvenile or nonfruiting
condition for a greater number of years. Young trees often grow very
upright, and become so dense that the grower is tempted to thin-out the
branches. It has been shown, however, that early fruit bearing will open
out a tree much more effectively than pruning. With the young tree,
remember: light pruning, early bearing, a spreading tree. (Figure 1)
Central-leader type of tree. There are 7 main branches
distributed vertically and spiralled on the trunk and
attached by wide, strong crotches.
Clean, Flush Cuts Heal More Quickly
Make pruning wounds flush with
the limbs to which the unwanted branches are attached. The exception to
this rule is with peach. With peach use a collar cut rather than flush
cuts. Wood healing is more rapid when the bark ridge at the base of
larger limbs is not removed during a pruning cut. Where one-year-old
wood is being pruned, make the cut as close as possible to a bud to
facilitate healing. A stub and/or ragged edges at these points greatly
delays the healing of the wound and increases the probability of drying
out and infection. This is particularly important with peach because
canker may enter where healing is delayed.
Narrowed-Angled Crotches are Weak
Where the crotch angle is less
than 35 degrees the attachment will be weak because of the inclusion of
bark. The tissues in narrow crotches (Figure 2) are slower to mature in
the fall and may be injured by low temperatures, especially in test
winters. Narrow crotches are usually further weakened by water, ice, rot
organisms and canker. Thus, remove limbs that make sharp angles early.
This avoids possible loss of a large part of the tree later on due to
breakage from weight of fruit.
Structure of wide (a) and narrow (b) crotches. The narrow
crotch is structurally weak and contains a bark inclusion
(arrow), an entry point for insect or diseases (modified
from Cornell Agr. Expt. Sta. Bull. 419, 1923)
Pruning and Training at
When new fruit trees are dug in
the nursery, a large percentage of the finer root system is left behind
during the process. The new tree that once had a balance of leaves to
roots now develops more leaves than there is root system to sustain. The
resulting tree will be out of balance, resulting in poor growth.
To overcome this problem,
heavily prune all fruit trees at planting time before growth starts.
Remove at least ¼ of the potential leaf area. Eliminate all branches
below 60 cm. If the tree is tall enough, cut back the leader to about
80-90 cm, and remove all shoots. With well developed trees or older
trees having some limbs you wish to retain, you can cut these limbs back
to 2 or 3 buds and retain growth in that area. Totally remove limbs:
Consider the pruning at
planting time and over the next 2 or 3 years as a training process. The
final strength of the tree depends upon the wise selection of branches
and your ability to maintain the proper balance between these branches.
Mistakes made in this formative period may mean weak trees and, in
addition, the correction of errors may call for severe pruning in later
years - the removal of considerable portions of the bearing area and the
creation of large wounds subject to infection. It is critically
important that you build a strong framework in the early years.
The central leader training
system is recommended for all fruit trees. This tree "Christmas tree"
form is conical in shape, with a wide base and a narrow top. During the
early life of the fruit tree, keep this tree with judicious pruning.
Some trees, particularly sour cherry, peach and Japanese plum, do not
retain a dominant central leader for long. This is not a problem. The
central leader tree at maturity consists of 6-8 main scaffold branches
distributed vertically and spirally around the trunk (Figure 3), and
with the topmost branch (leader) well in the lead of the lower ones.
The vertical distance between
limbs occupying the same quadrant of the tree will vary from 10-80 cm
depending on the ultimate size of the tree. Limbs too close together
will result in excessive shading. This weakens the limb and leads to
poor fruit quality, reduced productivity and ultimately failure of the
If the branch angles at the
main trunk are sufficiently wide (over 35 degrees), there will be no
bark inclusions in the crotches, resulting in a strong tree.
With many cultivars the central
leader will slow in growth, making removal or heading unnecessary.
Keeping the central leader in the early years encourages wider angles on
the framework branches below it. The central leader of dwarfed trees
will be lost prematurely if allowed to fruit too soon.
3. It is extremely important to build a strong framework
in the early years.
Training the Young Nonbearing Tree
The less pruning during this period, the more quickly
the tree comes into bearing. Consequently, once the main branches are
selected, do minimal pruning until the tree is bearing. An early crop of
fruit, besides bringing early financial returns, slows down vegetative
growth and bends down the branches. This aids in controlling the height
of the tree, and opens up the tree to permit more light and better spray
coverage. Guard against too-early fruiting of the central leader.
Prune lightly in the third and fourth years, chiefly by
thinning-out rather than heading-back. Generally avoid heading-back from
the second year, until the trees are in heavy bearing.
Remove branches that form narrow crotches (less than 35
degrees) with the trunk. Eliminate branches that grow straight up or
into the tree, those that are weak and drooping, and those that tend to
cross or otherwise interfere with others.
Six or 8 main branches are usually sufficient to build a
good tree. With pear varieties susceptible to fire blight, and where
fire blight is likely to be serious, prune especially lightly and leave
more framework and secondary branches.
Pruning the Mature Fruit Tree
Most pruning is done when the trees are dormant, between
the time when the leaves drop in late fall and when the buds begin to
swell in early spring. The safest and best time is just before the buds
swell. The most risky time is very late fall and early winter. Dormant
pruning of peach and nectarine increases the risk of winter injury;
prune during the bloom period.
In the orchard, start spring pruning early enough to be
completed before the leaves appear. The risk of winter injury increases
if pruning is begun too early. Pruning followed by low temperatures
means winter injury - not always seen but almost sure to be present. The
amount of injury is directly related to the length of time between the
pruning operation and the temperature drop; the shorter the time, the
greater the injury.
All pruning has a dwarfing effect, but dormant pruning
produces the most new growth. If you want new vegetative growth, dormant
pruning is the way to get it. The harder the cutting, the greater is the
response in new shoot growth. The response takes place in the area of
the tree where the cuts are made.
Pruning During Bloom
Most growers prefer not to prune peach and nectarine
trees until the flower buds have advanced sufficiently to assess the
flower winter survival. Delaying pruning much beyond shuck split may
cause a serious loss of tree vigour.
Early Summer Pruning
Pruning has the greatest dwarfing effect in June and
early July. If you wish to reduce vegetative growth and prevent shoots
developing, this is the time to prune. But remember that early-summer
pruning has a very dwarfing effect. It first dwarfs the root system, and
then the whole tree.
Pruning at this time of year has little or no effect on
stimulating new vegetative growth. At the same time, it is not nearly so
dwarfing as early-summer pruning. The root system is dwarfed somewhat
but only moderately, as compared with the results of early-summer
This may be the time to reduce the height and width of
your trees by cutting back the new growth. The amount of cutback would
depend on the growth, vigour and age of the tree. A well-grown tree with
a good crop could have new growth reduced by 1/2 to 2/3. This will let
in more direct sunlight to colour the fruit. It will also reduce
vegetative growth, which makes more sugars available to the developing
fruit, and results in improved flavour, although fruit size may be
Pruning cuts will not heal at this time of year, but in
order to spread the work load over more time, some pruning might be
started in early fall. Start with the oldest trees, and cease all
pruning operations well before any chance of a severe temperature drop.
Do not prune peach and nectarine trees in the fall because of the
ever-present threat of canker.
Summary of Rules for Pruning Bearing Trees
Cut out broken, dead, or diseased branches.
Where 2 branches closely parallel or overhang each
other, remove the least desirable, taking into account horizontal and
Where possible, prune on the horizontal plane; that is
leave those laterals on the main branches that grow horizontally or
nearly so, and remove those that hang down or grow upward.
Thin all varieties to permit thorough spraying and the entrance of
sunlight and air.
Where it is desired to reduce the height of tall trees, cut the leader
branches back moderately to a well-developed horizontal lateral.
Prune the lower branches of broadheaded or drooping varieties to
Varieties that tend to produce numerous twiggy, lateral growth should
have some of this growth removed to prevent overcrowding.
Make close, clean cuts. Stubs encourage decay and canker, thus forming a
source of injury to the parent branch or trunk.
Prune moderately. Very heavy pruning is likely to upset the balance
between wood growth and fruitfulness, and generally should be avoided.
Prune regularly. Trees that are given some attention each spring are
more easily kept in good condition than trees that are pruned
Prune that part of the tree where more growth is required. This is
particularly important with old trees. New growth will be stimulated
only in those parts of the tree that were pruned. Reduce pruning to an
absolute minimum where growth is already excessive.
Do not remove a branch unless there is a very good reason for doing so.
Leaves are the food-manufacturing organs, and if the leaf area is
reduced unnecessarily, the tree will be reduced in growth or
fruitfulness or both.