Quote: The open vase with Nemaguard rootstock, planted at 16 x 18 foot spacing and pruned
using the minimally pruned method, is currently a very economically efficient training system
for fresh-shipping stone fruits in most areas of California.

ORCHARD SYSTEMS FOR NECTARINES, PEACHES AND PLUMS:
TREE TRAINING, DENSITY, AND ROOTSTOCKS

Kevin R. Day1and Ted M. DeJong2
University of California

1Tree Fruit Farm Advisor, Tulare County, 2500 W. Burrel, Visalia, CA 93291;
2Professor of Pomology, University of California-Davis, Davis, CA 95616.

Presented at the Curso Internacional de Fruticultura de Clima Templado-Frio in Mendoza,
Argentina, June 16-20, 1998

INTRODUCTION
Choosing an orchard training system (including rootstock) is one of the most important decisions
a grower is called upon to make.While poor varieties can be changed over through grafting, the
original training system is difficult to change, and the rootstock impossible.For this reason,
growers should carefully consider their choices prior to planting.

Probably the biggest mistake made in developing a training system is not having a clear picture
of how the orchard should look when mature.Additionally, one must have a clear plan as to how
to get the orchard to that point.If a grower does not know what he wants or how to get there, it
is impossible to give proper directions to workers.

It is therefore very important for growers to have a plan for developing the orchard system prior
to planting. When evaluating an existing orchard system, some important questions to consider
are:

1.

What steps were taken, and when, to get the orchard to look like it does?Consider type,
timing, and severity of both dormant and summer pruning.
What were the major factors considered in developing that system?Consider fruit
production, fruit quality, labor savings, wind protection, etc.
Where was the system developed?Possible differences in climate, soil, sunlight, length of
growing season which may substantially alter tree growth pattern and vigor must be
considered.
Is there a dwarfing rootstock involved?If so, is this rootstock adaptable to your situation?If
not, can the system work without that rootstock?

2.

3.

4.

A carefully planned and designed system, appropriate for your situation, cannot be implemented
until these types of questions are asked and understood.

EVOLUTION OF CALIFORNIA SYSTEMS
The Open Vase
For more than 150 years, the open vase system has dominated California orchards as the
preferred system for growing fresh-shipping stone fruits.The system was originally planted on
wide spacings, 20 to 25 feet apart in both directions, to allow easy cultivation and cross
cultivation with mules, horses, and later the more primitive mechanized equipment.In the 1950s
and ’60s chemical herbicides were introduced and the need for cross cultivation was reduced or
eliminated.Consequently, tree spacings could be slightly reduced.Today, popular spacings are
18 to 20 feet between rows and 16 to 20 feet between trees down row.

Trees are trained to 3 or 4 primary scaffolds arising from a short central trunk.These scaffolds
then are each allowed to branch into 6 to 8 secondary scaffolds.These in turn may branch so
that at the top of the tree there are often as many as 10 to 14 tertiary growing points.Fruitwood
is developed off the primary, secondary, and tertiary scaffolds.

The open vase system is simple and easy to develop.Planting costs are low because of the low
tree densities involved.Light is easily managed due to the open center nature of the tree that
allows excellent light penetration when managed properly.As grown, the system has two
drawbacks:1) it is slow to come into production even under vigorous growing conditions, and
2) labor costs can be expensive because trees are generally allowed to grow to 12 to 14 feet in
height, requiring considerable ladder work.

Hedgerow Systems
In the 1960s and 1970s, hedgerow systems were introduced to California from Europe.There
was much discussion about how labor costs would be reduced since trees could be harvested,
pruned, or thinned either mechanically or with mechanical assistance.University of California
trials on these systems were initiated in 1972 (Gerdts et al., 1979).

The most popular of these systems was eventually termed the “Parallel V”or “California V”and
was similar to the palmette system.Trees were planted on much narrower between-row spacings
of 12 to 16 feet.Trees within the row were 8 to 12 feet apart.Two primary scaffolds oriented
parallel with the row were allowed to develop.Fruitwood then was developed from these
primary scaffolds.In the best orchards, secondary branching of the primary scaffolds was not
allowed.This was to help prevent the tree being dominated by structure rather than fruitwood.

Another system, based on the central leader used in apples, was also planted in California.In
this system, trees were also planted in close hedgerows 12 to 16 feet apart, but the trees were
even closer down the row—usually 5 to 8 feet apart.

Both of these systems were very productive in the early years after planting—especially the
central leader with its very high tree densities (Table 1).However, these systems became very
difficult to manage after the trees reached their full size with shading and loss of fruitwood
becoming large problems.Often growers did not understand or have a clear and well-thought-
out plan for managing the vigor of these orchards.Most responded by making heading cuts to
limit tree height and size.These cuts stimulated vigorous regrowth that usually just made the
problem worse.Growers also had a difficult time determining when and how to summer prune
the trees.Additionally, mechanical or mechanically aided devices for saving labor did not work
out.

Table 1.Summary of the initial high density peach planting trials at the Kearney Agricultural
Center; trees planted in 1972, cumulative yield from 1974 through 1978 (after Gerdts et al.,
1979).

Spacing
(feet)

Trees
per acre

Cumulative
yield (t/acre)

Variety

System

Springcrest
Springcrest
Springcrest
June Lady
June Lady
June Lady
Fantasia
Fantasia
Fantasia
O’Henry
O’Henry
O’Henry

8x15
10x15
22x19
8x15
10x15
22x19
8x15
10x15
22x19
8x15
10x15
22x19

363
290
104
363
290
104
363
290
104
363
290
104

Central leader
Parallel V
Open vase
Central leader
Parallel V
Open vase
Central leader
Parallel V
Open vase
Central leader
Parallel V
Open vase

42.6
44.1
23.7
54.6
46.4
28.0
76.3
58.8
42.0
72.3
65.5
38.3

Successful growers managed these orchards by controlling excessive vigor through proper
fertilization and pruning.Excessive amounts of nitrogen were avoided; most orchards received
no more than 50 to 125 pounds of nitrogen per acre annually. Also, and most importantly,
pruning tactics centered on the use of thinning cuts rather than heading cuts.These growers
found that four or five light, frequent summer prunings were more beneficial than one or two
severe prunings.The use of mechanical topping and side-hedging was eliminated.These tactics
made the orchards much more manageable.Most growers, however, lost patience with these
systems and replaced them when the orchards got old or production dropped off due to shading
or other problems.

Today there are only a few hedgerow-trained orchards in the fresh-shipping region of central
California.Most of these are managed by one large firm that has taken the time to understand
these systems.The system they have settled on is the parallel V at a spacing of 8 x 12 feet.All
hand labor is performed using ladders.

TrellisSystems
Trellis-based systems have not worked out in California.Many have been tried, mostly vertical
hedgerow systems, but also some Tatura type “V”plantings.Under our climate, these systems
have not been necessary to prevent wind damage.Growers made similar mistakes to those
encountered with the other hedgerow systems, and vigor became difficult to control in these
orchards.A complicating factor with trellis systems is that the California fruit industry replaces
varieties about every 8 to 12 years.At costs of $3000 to $5000 per acre for the support system
alone, the trellis systems were viewed as too expensive to remove with the trees.Often the trellis
was left in place, but this made replanting difficult since ground modification such as deep