1. Info
The fruit wall: are tall trees really
necessary?
A large number of canopy shapes and planting configurations are used in fruit growing
worldwide. In the past, but even today, in China for instance, tree canopies were made up
by complex structures, with 3 levels of organization, starting from the main stem up to
big branches, minor branches and bearing wood. Even in modern orchards based on conic
shaped systems there is a robust secondary structure in “centrifugal pruning” with the aim
of having productive wood and crop in the periphery (Figure 1). The height and width of
trees has not only a major influence on production and quality, but also on many cultural
practices and on crop protection.
Many fruit growers and consultants are con-
vinced of the advantages of tall trees, especially
in fruit-growing areas of South Tyrol, Italy, where,
they claim, the expensive land is better exploited
by tall trees. However, if we take into account
the additional costs and difficulties of produc-
ing apples in the top of the tree, the situation
changes. Working platforms are expensive and
picking from ladders is slow and risky. There is a
relationship between tree height and between-
row spacing, which in turn is a function of tree
canopy width, and the machines available on the
farm (tractors, mowers, etc.). Assuming that grow-
ers can manages to keep trees short and slender,
the question remains how much can the height
of the tree be reduced without this negatively
affecting light interception and consequently,
yields. The 1.5 metres clear alley required for the
machinery can in modern orchards be achieved
using very different systems. For instance, fruit
walls can achieve the same production volume
(for example, 80 tonnes per hectare) by chang-
Tree shape
Mechanical pruning is
an important tech-
nique when creating
a fruit wall. Machines
work quickly, whether
or not the trees have
leaves. They also con-
sistently prune the
tree into the correct
shape. In addition,
pruning machines are
flexible to deploy and
they can be used the
year round, also in
periods when there is
a limited amount of
labour available.
Alberto Dorigoni
Fondazione Edmund Mach
Center for Technological Transfer, Italy
alberto.dorigoni@fmach.it
Franco Micheli
Fondazione Edmund Mach
Center for Technological Transfer, Italy
50cm100cm150cm200cm
Figure 1: ‘Centrifugal effect’ of long pruning (Chile).
Alberto Dorigoni
EFM 2015-0610

2. ing the parameters of the planting system from
a few rows of large, tall trees to many rows of
low, narrow fruit walls (Figure 2).
Advantages of short trees
The advantages of short and thin fruit walls con-
cern management, cultivation characteristics and
environmental aspects. With small pedestrian
size trees, no work platforms or ladders are re-
quired,whichissaferfortheworkers.Allhorchard
management operations, from pruning through
thinning to harvesting, can be done faster and
easier from the ground. Picking aids can be em-
ployed more efficiently. The quality of the fruit is
more homogenous, because there is less differ-
ence between inside and outside of the canopy.
Moreover, every form of mechanisation is easier
for a low fruit wall than for standard trees. Con-
sider for instance the use of flower thinning ma-
chines, pruning, tunnel sprayers, weed control,
etc. The lower support system required for short
trees is easier to install and the posts do not need
to be joined together transversely. It is also easier
to protect the trees with multifunctional nets
from codling moths and hail. Such nets can also
be used to thin some varieties by closing them
around the trees during full bloom. In fact nets
can be used at bloom time to physically hinder
bee activity and reduce the available light result-
ing in more fruit abscission.
Disadvantages of low trees
Because there are 50% more rows of low fruit
wallsthanwithstandardsystems,cropprotection
takes more (driving) time. The additional driving
time is in part compensated by the higher driv-
ing speed. The reintroduction of the two-row
planting system can be an alternative. Orchard
Regulating growth
There are of course
many supplementary
measures that can
be used to regulate
growth and that can
help to keep the fruit
wall low and nar-
row. These include
root pruning, the use
of chemical plant
growth regulators
and controlled water
stress.
Figure 2: At a between-row distance of 2.80 metres, there is a gap available between the fruit walls
of 2.00 metres for the machines. In 2014, this ‘multi-leader’ Golden Delicious orchard in South Tyrol
achieved a production of 87 tonnes per hectare (53 kg/tree x 1.650 trees/ha).
Alberto Dorigoni
2.0m
2.7m
2.8m
0.4m 0.4m
bearing
wood
Figure 3: Golden Delicious on the MM106 rootstock becomes surprisingly
dwarfed when these trees are cultivated as multi-leader trees with six le-
aders instead of a spindle. These trees with six leaders are 2.50 metres tall.
2.3 m
Alberto Dorigoni
11EFM 2015-06

3. Fig: Cultural practices improved by fruiting wall
– Hand pruning
– Hand thinning
– No limb bending
– Branch renewal
– Harvest
– Mech. harvest aids
Mechanical thinning
Mechanical pruning
Mech. weed control
Less PGR’s
Less spraying volume
Faster leaf drying
Reduced drift
Tunnel sprayers
Multi-task nets
SSCD
FRUITING WALL
MANAGEMENT
ADVANTAGES
(Economic
sustainability)
ADVANTAGES IN
MECHANIZATION
(Ecological
sustainabilty)
AGRONOMIC
ADVANTAGES
Light interception / penetration
(no distinction between
inside and outside)
life may be diminished by the tendency of trees
to grow upwards and lose quality in the lower
portions of the canopy. However, using the cor-
rect cultivation techniques, it is possible to keep
a good balance between vegetative growth and
cropping and to overcome the disadvantages
mentioned.
Techniques used to form fruit
walls and to keep them in shape
Even though genetic characteristics unargu-
ably determine vigour, the shape and size of
fruit trees is mainly determined by external fac-
tors. This means that cultivation techniques can
be employed to create very different canopies
on genetically identical trees. There are various
ways to “de-structure” tree canopies and get rid
of large branches.
Increasing the number of
leaders
Double leader-trees and ‘multi-leader’ (ML) trees
have a natural tendency to form a narrow and
dense hedge with little or no secondary struc-
ture. This is because the vigour is distributed
over more than one leader as the only struc-
tural wood. Since, as far as vigour is concerned,
increasing the number of leaders has the same
effect as using a more dwarfing rootstock, the
EFM 2015-0612

4. Various advantages
The objective to im-
prove the economics
and ecologic aspects
of the fruit industry
can be accomplished
by just changing the
tree shape. From
the crop protection
viewpoint, the fruit
wall also has advan-
tages. Thanks to the
low and narrow tree
canopy, the distribu-
tion of crop protec-
tion products is good
throughout the year.
Various machines and
techniques that are
common in wine pro-
duction can be used
in modern orchards
consisting of fruit
walls in a new scenar-
io of orchard param-
eters that involve tree
height, spacing, ma-
chinery, etc.. People
from outside of agri-
culture, including the
tourist industry, can
also benefit from the
lower input of chemi-
cals and the reduced
drift associated with
low fruit walls.
2011 cut
2012 cut
New shoots
and
buds
10cm20cm30cm40cm
Hand pruning
“Lorette”
Crown of 4
new leaves
Stalk of the
old leaf
Distance from the trunk
Figure 4: Golden Delicious Bibaum: Several consecutive years of summer
pruning have promoted the growth of productive shoots close to the trunk.
Figure 5: The strong “de-structuring” effect of summer pruning on a vigorous branch of the Empire
apple variety. This variety normally grows long branches.
Alberto Dorigoni
Alberto Dorigoni
1-year old wood produce new spurs between the
cut and the tree trunk (Figure 4). ‘Lorette’ prun-
ing, and other forms of non-dormant pruning,
helps to remove old, structural wood and to turn
it back into bearing wood. The effect is so strong
that some varieties including Empire lose their
natural centrifugal growth habit (Figure 5). Prun-
ing after harvest, compared to winter pruning,
is also an interesting measure to reduce vigour.
number of leaders is an additional variable that
can be used when determining the correct sys-
tem in new orchards.
Trees with multiple leaders are positively assessed
throughout the world. Started in Italy, where the
Mazzoni tree nursery has patented trees with two
leaders as ‘Bibaum’, the growing system with two
leaders was implemented in particular in Spain
and the United Kingdom, but also in the rest of
Western and Eastern Europe. The first orchards
of multi-leader trees have also been planted
in Chile, the United States, Australia and New
Zealand. The width and height of multi-leader
trees can be controlled much better than spin-
dle-shaped trees. This applies even for trees on
vigorous rootstocks (Figure 3).
Short pruning in summer
While long pruning and thinning of strong
branches is recommended if centrifugal growth
of the tree is desired, any shortening of branches
tends to bring back bearing wood near the trunk.
Of course, such short pruning, when not accom-
panied by the correct strategy, can cause pow-
erful regrowth, in particular if it is performed in
winter. At the beginning of the 20th
century, the
Frenchman Louis Lorette demonstrated that the
growth of vigorous apple and pear trees could be
tempered by repeated manually pruning trees in
summer. Similar effect can be achieved by me-
chanical pruning in summer. The ‘de-structuring’
principle is simple: summer pruning performed
early directs the flow of sap to the fruits and buds
instead of to the shoots. A few months later, the
terminal stipulary eyes at the base of the leaf on
13EFM 2015-06