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Contribution 1 983-1 1E

Management of
high-density orchards
in Quebec

630.
C759
C 83
c.3

Canad

The map on the cover has dots representing
Agriculture Canada research establishments.

Management of
high-density orchards
in Quebec

RAYMOND L. GRANGER
Research Station
Saint-Jean-sur-Richelieu, Quebec

Technical Bulletin No. 17 revised

Research Branch
Agriculture Canada
1983

Copies of this publication are available from

Roseau h Station

Research Branch

Agriculture Canada

Pb. Box 457

Saint-Jean-sur-Richelieu, Quebec

J3B 6Z8

Produced by Research Program Service

©Minister of Supply and Services Canada 1983

£galement disponible en francais sous le titre
Conduite des vergers a fortes densites au Quebec

Resume

L1 arboriculture fruitiere au Quebec subit presentement des changements
rapides et radicaux. Les pommeraies constitutes d'arbres de taille
conventionnelle se transf orment en plantation a fortes densites ne
comportant que des arbres nains ou semi-nains. Les rangs simples y
predominent . Les nouvelles formes les plus en vogue sont la "cloche
etroite" et la "palmette oblique". Chez le pommier, les porte-gref f es
les plus utilises sont la 'Mailing 9', le 'Mailing 26', 1' 'Ottawa 3'
et 'Mailing 7'. Les resultats des recherches initiees a la Station de
Recherches de Saint-Jean tendent a demontrer que 1' 'Ottawa 3' est
superieur. Dans la conjoncture economique actuelle, huit hectares de
pommiers nains plantes a forte densite pourraient procurer a l'arbori-
culteur fruitier du Quebec un revenu convenable.

Pour le poirier, on y utilise encore le franc de 'Bartlett' comme porte-
gref fe. Par ailleurs, les francs du prunier indigene, le 'Myrobolan'
et le 'Brompton' sont les porte-gref fes du prunier les plus employes.
Les essais effectues avec d'autres porte-gref fes de poirier et de prunier
sont tres limites. Les cultivars de griottiers et de cerisiers a fruits
doux sont surtout greffes sur les francs de 'Mazzard', de 'Mahaleb' et
du clone 'Mazzard F12'.

Une serie de questions et reponses concernant les particularites de la
pomiculture au Quebec apparait en annexe.

Contribution no J. 850 de la Station de Recherches, Direction de la
Recherche, Agriculture Canada, Saint-Jean-sur-Richel ieu , Quebec.

Communication presentee le 20 aout 1980, au Colloque International
sur l'Horticulture patrone par les Floralies de Montreal, Quebec.

Abstract

Quebec's fruit growing industry is now experiencing rapid and important
changes. Standard size fruit trees are being replaced by dwarf and semi-
dwarf ones. Single row systems are prevailing at the moment. The most
common training systems are the "slender bell" and the "oblique palmette",
Concerning apples, the 'Mailing 9', 'Mailing 26', 'Ottawa 3' and
'Mailing 7' rootstocks are in prominent use. Of these, 'Ottawa 3' showed
a superior performance. Given present economic conditions, it seems
that eight hectares of dwarf apple trees planted in a high density
system can viably support one Quebec grower.

'Bartlett' seedlings are still the most popular rootstock for pears in
this province while native plum seedlings, and the clones 'Myrobolan'
and 'Brompton' are the usual plum rootstocks. Trials with other plum
and pear rootstocks have been very limited. Sour and sweet cherry
cultivars are mainly grafted on 'Mazzard' and 'Mahaleb' seedlings or
on 'Mazzard F12' clones.

A series of questions and answers regarding some unusual aspects of the
regional fruit tree culture is included.

Contribution No J 850, Research Station, Research Branch, Agriculture
Canada, Saint-Jean-sur-Richelieu, Quebec.

Paper presented at a colloquium on horticulture held at the Inter-
national Floralies, Montreal, Quebec, August 20, 1980.

In recent decades, fruit growers in most pome - and stone-fruit producing
countries have tended to cultivate fruit trees which are adapted to their
own regions; small, early-bearing, heavy producers of quality fruit. It
has been found that profits depend on optimum fruit tree density over a
given area, together with good orchard management.

Quebec's fruit growers too have begun to realize that dwarf and semi-
dwarf fruit trees, properly managed, are their only hope of survival.
Apple orchards, particularly those with 90 to 180 trees per hectare,
are being replaced by new plantings with 600 to 3 500 trees per hectare.
The same tendencies, although slightly less marked, are evident among
pear, plum and cherry growers.

Training systems

The training systems in most common use in Quebec at the present time
are the "slender bell" and the "oblique palmette" methods (fig 1 and
PI. I, figs h and j). Trees trained to these forms are normally provided
with some kind of support and are nearly always planted in single rows.
Some trees are also left "free-growing", without any support.

Local tests tend to demonstrate that, in terms of apple production and
profits, of the following four training systems, the "free-growing tree",
"Van Roechoudt palmette", "oblique palmette", and "slender bell", the
two most promising forms are the "slender bell" and the "oblique
palmette"* (pi. I, figs h, i, j and k) . The "slender bell" is closely
related to the "slender spindle" described in this report by Dr. S.J.
Wertheim. This form is obtained either by leaving the central stem
intact after the second foliation, or by cutting it back each year,
depending on whether the French "vertical axis" or the Dutch "slender

* All these training systems are described in Saint-Jean Research Station
bulletin J-642.

Figure 1 Principal training systems used for apple trees in Quebec:
A slender bell or slender spindle
B oblique palmette

B

spindle" system is being used. In the first case, the leading shoot must
be attached to a good-sized stake or raised on wire support, otherwise
the weight of the crop will soon cause it to bend and break (PI. II,
fig g) . At the Frelighsburg experimental sub-station, the "slender bell"
method has encouraged heavier and earlier fruit production than the other
training systems (Table 1) .

TABLE I Average production (kg/ha) by training system and density of
4th-year dwarf and semi-dwarf apple trees, Frelighsburg 1979

Training system Density** in trees/ha Average

2960 1480 740

Slender bell 9220 a 5344 a 7282 a

Oblique palmette 7320 b 3870 c 5595 b

Free-standing 5340 a 3521 a 4431 c

Van Roechoudt 3943 b 1806 b 2875 d

palmette

Our current tests appear to indicate the need for a stake or point of
attachment to support dwarf and sometimes even semi-dwarf trees, which,
under our climatic conditions, have a strong tendency to bend when the
soil softens during the spring thaw (PI. II, fig f). The same phenomenon
may also occur during the summer, as a result of wind, rain or the weight
of a crop which is poorly distributed around the central axis. This is
why, as shown in table 1, "free-standing" apple trees show reduced
production as compared to "slender bell" and "oblique palmette" trees.
Since apple trees trained by the "Van Roechoudt palmette" system must be
severely pruned in their 2nd and 3rd seasons, it is difficult to compare
them to other apple trees in terms of production.

a Non-significant difference (at the 5% level) form data followed by
the same letter.

** In this text, density will be described as high (2960 trees/ha),
medium (1480 trees/ha) or low (740 trees/ha).

In Quebec, since the weight of snow and ice tend to break the lower
branches of dwarf or semi-dwarf trees, it is often important to attach
the lateral branches of these fruit trees to a central support or wire
(PI. II, fig e).

The commonest training system for pear, plum and cherry trees is the
"free-standing" or "bell" tree, normally without any form of support.
The espaliered forms used in British Columbia for the 'Anjou' pear do not
yet exist in Quebec. Similarly, the system of training strong lateral
branches on sour cherry trees for easier mechanized picking is not yet
in use on Quebec. While some fruit growers have trained their plum trees
into the "goblet" shape, the most common and the most practical
forms for the plum tree in Quebec remain the "free-standing" tree and the
"bell" free.

Rootstoaks

Given present economic conditions, it is essential that fruit production
costs be reduced. With regard to apples, Dr. Ronald Tukey (1971) notes
that picking, pruning and pest control account for nearly 40 % of the
total of these costs. Other economic studies performed in the state of
New York (Snyder, 1968) have demonstrated that the use of dwarf and semi-
dwarf apple trees helps to reduce production costs considerably. The
same observation made in Quebec (Garon and Ouellet, 1978) has led us to
recommend the exclusive use of rootstocks which will produce trees of
dwarf and semi-dwarf size and which are adapted to our climatic
conditions. These include 'Mailing 26', 'Ottawa 3', 'Mailing 7' and
'Mailing 9'; the last-named, however, should be used only to a limited
extent .

'Mailing 9'

'Mailing 9' is a dwarfing rootstock which was tested at the Ottawa
Research Station from 1938 to 1970. There it proved to be cold-sensitive

(Davis et at. , 1948). In Russia, too, it is considered non-hardy
(Margolin, 1951 and Smirnov, 1960). In Quebec, 'Mailing 9', cultivated
on turfed land near Macdonald College, has survived our winters for at
least 22 years (Taper, 1979). However, after their first season, poorly
matured specimens of 'Mcintosh' and 'Spartan' cultivars on 'Mailing 9',
growing on bare ground at the Frelighsburg sub-station, suffered considerably
from the cold during the winter of 1975-76 (Rousselle et at. , 1976).

In our Frelighsburg experimental plots, young 'Mailing 9' was the least
productive of the dwarf-type rootstocks (Table 2).

TABLE 2 Average production (kg/ha) of 'Mcintosh' and 'Spartan' cultivars
per rootstock and planting density of 4th-year dwarf and semi-
dwarf apple trees, Frelighsburg 1979

Rootstock Density in trees/ha Average

2960 1480 740

Ott 3 14229 a 8756 a 4150 a 8972 a

M 26 7617 b 3797 c 3576 b 4696 b

M 9 7403 c 4312 b 1568 d 4605 c

M 7 6810 d 3697 d 2104 c 4077 d

a Non-significant difference (at the 5% level) from data followed by
the same letter

This rootstock appears to perform well with the cultivars best adapted
to high-density planting, such as 'Empire'", 'Golden Delicious'* and 'Red
Haralson'** (PI. I, e and f ) .

At Vineland, Ontario, 'Mcintosh', 'Cortland' and 'Red Delicious' trees,
all on 'Mailing 9', have produced an average of two bushels per tree
from the 5th to the 10th season. At the same location, 'Mcintosh',
'Spy' and 'Red Delicious' apple trees on 'Mailing 9', considered
relatively old (between 20 and 25 years old) , produced an average of

* cultivar sensitive to cold injury; should be grown in a selected area
where winter damage does not usually occur

** gives poor quality fruits when grown under harsh winter conditions

54 kg (3 bushels) of apples per tree (Hutchinson, 1964). Some of these
trees produced up to 72 kg (4 bushels). In Ottawa, the annual yield
of 'Mcintosh' trees on 'Mailing 9' has been 16 to 27 kg per tree between
the ages of 12 and 25 years. 'Mailing 9' requires soil which is
relatively heavy and well watered, but well aerated and drained (Granger
et al, 1974).

Based on the results obtained on our Frelighsburg plots with 'Spartan'
and 'Mcintosh' cultivars on 'Mailing 9', it appears that the optimum
density for this rootstock is approximately 2960 trees per hectare with
the "slender bell" system. With other training systems on 'Mailing 9',
that is, "free-standing", "oblique palmette" and "Van Roechoudt palmette"
trees, they also produce their optimum yield per tree at high density.
These densities are 2960 and 1480 trees per hectare for the "slender
bell" and "oblique palmette" systems respectively, and 1480 and 740 trees
per hectare for the "Van Roechoudt palmette" and "free-growing" systems.

In recent years, some of our apple growers have found that the new virus-
free 'Mailing 9' is too vigorous and not as productive as the older
specimens which were subject to virus diseases. It has also been noted
that, under our very humid climatic conditions, 'Mailing 9' tends to form
aerial root galls, known in English as burr knots; there galls interfere
with normal sap circulation and leave the tree more vulnerable to cold
and to certain diseases (PI. II, fig d).

'Mailing 26'

Created in 1929 at the East Mailing Research Station in England by a
cross between 'Mailing 16' and 'Mailing 9', 'Mailing 26' was distributed
for some time as number 3426. It is currently one of the most popular
rootstocks sold in Canada. It has been tested at the Ottawa Research
Station and is still being tested at the Saint-Jean Research Station in
Quebec, the Smithfield, Vineland, Harrow, Simcoe and Guelph Research
Stations in Ontario and the Kentville Station in Nova Scotia (Granger

et als 1974).

At Vineland, Ontario, 'Mailing 26' has produced an average of two bushels
from the 5th to the 10th season. At Frelighsburg, with 'Spartan' and
'Mcintosh' cultivars, its early yield has been superior to that of
'Mailing 9' and it has been ranked second (Table 2). It should be noted
that 'Mailing 26' is more compatible with the 'Mcintosh' cultivar than is
'Mailing 9' (Table 3) .

TABLE 3 Average production (kg/ha) of 4th-year dwarf and semi-dwarf
apple trees, Frelighsburg 1979

Rootstock Cultivar

'Spartan' 'Mcintosh'

Ott 3 8972 a 8691 a

M 9 6564 b 2552 d

M 26 5206 c 4186 c

M 7 3298 d 4855 b

a Non-significant difference (at the 5 % level) from data followed by
the same letter.

When cultivated in suitable soil, that is, good, well-drained, gravelly
soil with good water retention, 'Mailing 26' produced heavier vegetative
growth than 'Mailing 9'. In our experimental plots, however, 'Mailing
26' has produced heavier vegetative growth than 'Mailing 9', thus
necessitating more extensive pruning (Table 4) .

9

TABLE 4 Average trunk diameter of 4th-year dwarf and semi-dwarf apple
trees, Frelighsburg 1979

Rootstock Density in trees/ha Average

2960 1480 740

M 7 4.00 a 4.32 a 4.49 a 4.27 a

M 25 3.85 ab 3.84 b 4.44 a 4.04 ab

Ott 3 3.65 b 3.87 b 3.94 b 3.82 b

M 9 2.83 c 2.99 c 3.01 c 2.94 c

a Non-significant difference (at the 5% level) from data followed by
the same letter

Of the dwarf-type rootstocks, *M 26' has produced the highest proportion
of large fruit, as reflected by average apple weight (Table 5).

TABL 5 Average weight (g/fruit) of fruit from 4th-year dwarf and
semi-dwarf apple trees, Frelighsburg 1979

Rootstock Density in trees/ha Average

M 7
M 26
M 9
Ott 3

a Non-significant difference (at the 5% level) from data followed by
the same letter

In our climate, 'Mailing 26' has proven much hardier than 'Mailing 9'
(Rousselle e t at., 1976). Introduced to our region ten years ago, this
rootstock has not yet been affected by the cold. According to reports
from the Ottawa Research Station, 'M 26' is more sensitive to cold than
'Matus robusta 5' but in Minnesota these two rootstocks have been found

* a 150 g apple represents usually a commercially acceptable size

2960

1480

740

154 c
159 a
156 b
143 d

166 a
160 b
155 c
149 d

160 b

161 a
140 c
160 b

161 a
159 b
151 c
150 d*

10
to be equally hardy (Watkins, 1968; Granger et al3 1974).

In Quebec, 'Mailing 26' has been shown to be sensitive to bacterial
fire blight (Eruinia amylovora Burr. Winsl. et at) , although, after
grafting, this disease rarely affects the rootstock itself. The major
problem observed with 'Mailing 26' in Quebec involves its strong tendency
to develop aerial root galls or burr knots (PI. II, fig d) . To counter
this tendency, the exposed portion of 'Mailing 26' may be brushed with a
1 % solution of naphthaleneacetic acid (NAA) . This solution may be
mixed with a small quantity of white Latex-type paint. It is important
to treat the galls as soon as they appear, or they will form large
patches which will interfere with the circulation of the sap. It is
also totally inadvisable to use poorly perforated mouse guards around
the trunks, since they help to keep the crown and aerial base of the
tree in an atmosphere of constant humidity, which promotes the formation
of these galls. It is also important to eliminate tall grass or weeds
near the apple trees, since these too maintain a high percentage of
humidity at the foot of the trees. If it is necessary to use protectors
against field voles, it is therefore wise to use those which are made
of wire netting. Finally, it should be noted that Mailing 26 performs
very poorly in soil which is too light or too dry. In such cases,
irrigation is advisable.

'Ottawa 3'

Created at the Ottawa Research Station, this new rootstock is the result
of a cross between 'Robin' and 'Mailing 9' (1956). From 1967 to 1973,
it was tested at Ottawa and at Smithfield, Ontario. Multiplied and
assessed at the Frelighsburg sub-station since that time, it has been
distributed to a number of nurseries across Canada to meet the growing
demand from apple growers.

'Mcintosh' and 'Quinte' cultivars grafted onto 'Ottawa 3' since 1967 have
remained dwarf trees, slightly smaller than on 'Mailing 26' but somewhat

11

larger than on 'Mailing 9'. At maturity, a 'Mcintosh' apple tree on
'Ottawa 3' can be maintained at a height of slightly less than three
metres; the fruit is therefore very easy to pick (Granger et al, 1974).

'Ottawa 3' has proven very hardy, comparing favourably to xMalus robusta
5'. In the eastern part of the country, apple tree survival, under
unfavourable climatic conditions, has sometimes been ensured by the
hardiness of their rootstocks. These conditions may still prevail. It
is therefore important to use hardy rootstocks wherever possible.

'Ottawa 3' has provided very good yields, considering the small size of
the trees it produces. For instance, two-year-old 'Quinte' and
'Mcintosh' trees on 'Ottawa 3', planted in 1967 at Ottawa, began to bear
in 1970 (4th season), producing an average yield of 5.45 kg per tree
and reaching 18 kg in 1972 and 1973 (6th and 7th seasons). Yields from
apple trees grafted onto Ottawa 3 have thus proven superior to those
from apple trees on 'Mailing 26'. In addition, 'Ottawa 3' has produced
'Mcintosh' and 'Quinte' apples somewhat earlier than 'Mailing 26', but
the quality of the fruit produced on both rootstocks has been excellent.
At the Frelighsburg sub-station, the results obtained with 'Ottawa 3'
have been similar to those cited above. However, with the training
systems most appropriate to it, 'Ottawa 3' has shown better performance
at Frelighsburg than at Ottawa. In fact, table 2 shows that with
'Mcintosh' and 'Spartan' cultivars and trees trained to the four methods
mentioned at the beginning of this article, 'Ottawa 3' is easily the best
rootstock for producing high, early yields of quality fruit.

The training system which appears best suited to 'Ottawa 3' is the
"slender bell" (Tables 6 and 7).

12

TABLE 6 Average production (kg/ha) of dwarf and semi-dwarf 'Spartan'

apple trees with "slender bell" (1) and "oblique palmette" (2)
training systems, 4th season, Frelighsburg 1979

Rootstock

Density

trees/ha

Ave

rage

2960

1480

Ott 3

M 9
M 26

M 7

(1)

15170 a

15537 a

8962 b

6621 c

(2)
13287 a
9048 b
6029 c
7790 d

(1)
11350 a
7448 b
5347 c
3825 d

(2)
7625 a
3643 c
5260 b
1370 d

(1)

13260 a

11493 b

7155 c

5223 d

(2)
10458 a
6346 b
5645 c
4580 d

a Non-significant difference (at the 5 % level) from data followed by
the same letter.

TABLE 7 Average production (kg/ha) of dwarf and semi-dwarf 'Spartan'

apple trees with "free-standing" (1) and "Van Roechoudt palmette"
(2) training systems, 4th season, Frelighsburg 1979

Rootstock

Density trees/ha

Avera;

ge

1480

740

Ott 3
M 9
M 26
M 7

(1)

8242 a
7886 b

4141 c
3224 d

(2)
7807 a
3520 c
4590 b
1361 d

(1)

3280 a
3125 a
5820 b
1580 c

(2)
5019 a
2309 b
1498 c

598 d

(1)
5761 a
5505 a
4980 b
2411 c

(2)
6413 a
2915 b
3044 b

978 c

a Non-significant difference (at the 5 % level) from data followed by
the same letter.

With this training system, however, and high-density planting, the
'Spartan' cultivar on 'Ottawa 3' has not proven to be significantly
superior to 'Mailing 9'. At this density, 'Spartan' fruit on 'Ottawa 3'
has tended to be small, thus reducing the weight of the crop. The
training system least suited to the 'Spartan' cultivar on 'Ottawa 3' is
that of the unsupported "free-standing" tree (Tables 6 and 7). This
indicates that an apple tree comprised of the 'Ottawa 3' rootstock needs

13

a stake or some form of support. Measurements of the trees on our
Frelighsburg plots confirm the above observations, that 'Ottawa 3' gives
the apple tree a degree of vigour between that of 'Mailing 9' and 'Mailing
26' (Table 4). It should be noted that too high a density (regardless
of the training system adopted) is likely to reduce the vigour of apple
trees on 'Ottawa 3' (Table 4). In general, medium densities (all training
systems combined) allow 'Ottawa 3' to achieve its optimum physiological
equilibrium. It attains its maximum performance, that is, each individual
tree produces its heaviest yield, with the "slender bell" training system
and medium density (1480 trees per hectare). However, the highest yields
per hectare were obtained when ' Spartan' /' Ottawa 3' trees were planted at
high density, even though, under these conditions, the average yield per
tree was lower (Tables 6 and 7). 'Ottawa 3' also appears to be as good
a rootstock for the 'Mcintosh' cultivar as for the 'Spartan' cultivar,
whereas both 'Mailing 26' and 'Mailing 9' proved less satisfactory as
rootstocks for 'Mcintosh' than for 'Spartan' (Table 3). However, without
irrigation and chemical thinning, 'Mcintosh' /' Ottawa 3' and 'Spartan'/
'Ottawa 3' trees tend to produce rather small apples (Table 5).

Used as an 8 to 10 inch interstock on the Malus vobusta 5 rootstock,
'Ottawa 3' has given excellent early yields at Ottawa and at
Frelighsburg. 'Mcintosh' and 'Quinte' cultivars grafted in this way
have given approximately twice the yield per tree of the same cultivars
grafted directly onto 'Ottawa 3' roots. 'Ottawa 3' has proven superior
to 'Mailing 26' when used as an interstock on 'Malus vobusta 5'.

To date, 'Ottawa 3' does not appear to be overly sensitive to virus
diseases. In certain cases, however, scions, including those of non-
indexed 'Jerseymac' and 'Macspur', have transmitted virus diseases to it,
with symptoms appearing at the graft point in the form of brown streaks
below the bark. Trees thus affected will die within a relatively short
time. In addition, in the nursery, this clone is extremely sensitive
to powdery mildew and the woolly aphid.

14

These disadvantages would be more or less negligible in the orchard, but
apple growers and nurserymen should nonetheless be advised to graft onto
'Ottawa 3' only those scions which have been indexed for the principal
virus diseases.

Multiplication of 'Ottawa 3' from stool bed layering is very difficult,
but relatively easy from root cuttings. Root cuttings of 'Ottawa 3'
kept in the greenhouse from February to May at the Saint-Jean Research
Station showed rooting rates of 600 and 850 per 1000 in 1972 and 1973
respectively. When propagated by means of soft wood cuttings, this clone
showed a rooting rate of from 62 to 65 % from 1969 to 1974. This
percentage is lower than that obtained with Malus robusta 5 but higher
than that obtained with 'Mailing 7'.

'Mailing 7'

This rootstock, known in France and England since the seventeenth century,
was reselected in 1959 by England's East Mailing Research Station (Tukey,
1964). It is the only rootstock currently available on a world-wide
basis which produces a semi-dwarf apple tree.

'Mailing 7', as one of the oldest rootstocks in use by apple growers,
is considered one of the safest in North America because it has performed
well under a multitude of soil and climate conditions. In Massachusetts
and in Michigan, it still plays a major role in new plantings. No supports
are used, and the trees receive minimum maintenance. 'Mailing 7' is
precisely the rootstock which can nevertheless perform profitably under
these conditions (Lord and Costante, 1977). With 'Mailing 7' as the
rootstock, unsupported trees given practically no pruning and allowed
to grow with no particular care in poorly drained, weedy soil have
performed well since 1957 at Frelighsburg (Granger, 1972). In their 9th
and 10th seasons, Melba, Mcintosh and Bancroft cultivars on 'Mailing 7'
have had low yields of from 20 304 to 38 394 kg/ha (average for the two
years and three cultivars combined) but the fruit was of excellent quality.

15

At low density, per-hectare yields of apple trees grafted onto 'Malus
vobusta 5' have been slightly higher than those of trees grafted onto
'Mailing 7', at 18 770 as opposed to 18 246 kg/ha. However, at maximum
density, the yields of cultivars on 'Mailing 7' have been superior to those
of cultivars on ' Malus vobusta 5', the difference being in the range of
1 778 kg/ha in favour of 'Mailing 7' for the 9th and 10th seasons combined.
More recent observations at the Frelighsburg sub-station have shown that,
of the 4 rootstocks tested, 'Mailing 7' has produced the lowest yields at
both high and low density, except with 'Mcintosh', which, when grafted
onto 'Mailing 7', produced more apples than when grafted onto 'Mailing 9'
or 'Mailing 26' (Tables 2 and 3). 'Mailing 7' thus appears to be better
adapted to 'Mcintosh' than 'Mailing 9' or 'Mailing 26' (Table 3). We have
observed that the training system best suited to 'Mailing 7' is the
"slender bell" and that, even with this rootstock, it is important to
support the trees; otherwise, yields decline (Tables 6 and 7). Finally,
'Mailing 7' has proven more vigorous than the other four rootstocks and
has produced the largest fruit (Tables 4 and 5) .

Mailing 7 has a taproot system, rather than a running root system as is
the case with the other three rootstocks discussed. As a result, it may,
at least under certain conditions (partial freezing of its roots, etc.),
suffer from a potassium deficiency. In addition, it has a strong
tendency to produce suckers and it has proven very sensitive to crown
gall (Agvohaaterium tumefaciens) (PI. Ill, fig h) . While the use of this
rootstock may seem to be an easy solution to many apple growers in
Quebec in view of observations in Massachusetts and elsewhere, a word of
warning is necessary; certainly 'Mailing 7 ' is a reliable rootstock for
the apple grower who wishes to obtain small or medium yields with minimum
effort. However, 'Mailing 7' is totally inadvisable for those who wish
to obtain volume and quality, or, in other words, to achieve maximum
profit form their operations. Tests performed at Vineland, Smithfield,
Saint-Jean and Ottawa show the relatively low productivity of Mailing 7
(Hutchinson, 1964).

16

Pear rootstoeks

The most popular rootstock for pear in Quebec is still the 'Bartlett'
('Williams') seedling. Although it is fairly slow to come into bearing
and relatively sensitive to bacterial fire blight (Erwinia amylovora
Burr. Winsl. et at). This type of rootstock has proven hardier and
more vigorous than certain quinces which are not adapted to our climate,
particularly quince C. However, Pyrus Ussuriensis has been a good
reliable and cold hardy rootstock in the province of Quebec.

The Angers quince, which is considered relatively hardy in Ontario and
at the Geneva, NY research station (Lapins, 1963), has received only
limited testing in Quebec. 'Bartlett' seedlings have proven compatible
with Quebec's most popular cultivars, 'Flemish Beauty', 'Clapp's
Favourite', 'Anjou', 'Bosc' and 'Bartlett' (PI. Ill, figs, b, c, d) . The
latter, because it is not a hardy variety, has not been profitable in
Quebec.

Since 1972, we have been testing native hawthorn seedlings (Crataegus L.)
at Frelighsburg in an attempt to produce earlier-bearing dwarf pear
trees. We have found the life expectancy of pear scions on hawthorns to
be extremely short. In general, a combination of this kind lasts only
about five or six years. We then began testing interstocks of 'Old Home'
on Crataegus roots. According to results obtained in Oregon, this
combination should produce a certain degree of resistance to bacterial
fire blight (Erwinia amylovora Burr. Winsl. et at), earlier fruiting and
moderate dwarfism. Unfortunately, the rooting rate for trees with these
double grafts has been only 25%; however, those specimens which took
root have performed well, have begun to bear early and have developed into
semi-dwarf pear trees. The best combination has been the scion on 'Old
Home' on seedling stock. As a result of these tests, some of our nurseries
have begun to use 'Old Home' as interstocks on seedlings. Preliminary
trials have indicated that 'Harbin' and 'Luscious' could be possibly used
as rootstoeks for pear in Quebec. We have not yet tested any of the

17

Russian or German rootstocks, such as the 'Melitopolskaya' and 'Severnaya'
quince, and the 'Pillnitz' //l, 3 and 5 quince selections or 'Pillnitz'
clones (Pyrus be tuli folia) , which are recognized as relatively dwarfing
and cold-hardy.

Plum rootstocks

For over half a century, the rootstocks most commonly used in Quebec for
plums have been native plum seedlings (Prunus amerioana) and East
Mailing's 'Myrobolan B'. With these rootstocks, plum trees are planted at
a density of approximately 450 trees per hectare. At the La Pocatiere
and Frelighsburg sub-stations, we have planted plum trees grafted onto
'Brompton' rootstocks at a density of 840 trees per hectare. This
experiment, begun in 1977, involves more than 30 plum cultivars on this
rootstock; these trees have begun to bear but it is still too early to
assess the results obtained.

At the Ottawa, Vineland and Geneva research stations, tests have dealt
with the dwarfing effect of sand cherry seedlings ('Prunus besseyi' ) used
as rootstocks (Blair, 1954; Hutchinson, 1964). Yields have proven
acceptable, the fruit has matured from 7 to 10 days earlier and quality
has been excellent. However, the trees have required solid supports and
it appears that 'Damson' -type scions are incompatible with these
rootstocks. At the Frelighsburg sub-station, we have grafted plum trees
onto 'Prunus tomentosa' but the survival rate was only 15 %. These trees
were approximately half the size of standard trees and could have been
planted at densities in excess of 1 500 trees per hectare.

Sweet and sour cherry rootstocks

The commonest rootstocks for sour cherry cultivars in Quebec are 'Mazzard'

and 'Mahaleb' seedlings and the 'Mazzard F12' clone. While 'Mahaleb'

seedlings are slightly dwarfing for such sour cherry cultivars as

'Montmorency', 'Northstar' and 'Meteor', they still produce trees which

18

are rarely smaller than 50 % to 75 % the size of standard trees. Lapins
(1963) reports that an interstock of the wild red cherry ( 'Prunus
pensylvanica' ) on a 'Mazzard' root has a strong dwarfing effect and is
compatible with the principal commercial sour cherries. At the Frelighsburg
sub-station, we have performed a number of tests with wild red cherry
seedlings which have always appeared to be compatible with scions of
commercial sour cherries. However, it is still too early to evaluate the
results obtained. Since we have not yet tested the English dwarfing
rootstalk 'Colt', we have no rootstocks which really allow us to plant
sweet and sour cherry trees (for amateur gardeners) at high densities in
Quebec.

Economic aspects

Although it is still too early in Quebec to be able to evaluate the
profitability of various forms of fruit trees cultivated at given
densities, the preliminary results obtained in our experimental plots and
by avant-garde producers show promising results. Moreover, Fisher (1969)
in British Columbia, Norton (1971) in the State of New York and Hutchinson
(1976) and Miller (1976) in Ontario have reported that, even in America,
high-density orchards were more profitable than conventional orchards.
Of course, according to the same researchers, excessively dense plantings
are no more profitable than those which are not dense enough.

For apple trees, the results from our experimental plots at Frelighsburg
show that for the year 1979 (4th season) the "slender bell" training
system with high-density planting was the most profitable combination
(profit of 2 042,50 $ per hectare). It was followed by the "oblique
palmette" system at high density (profit 1 457 $ per hectare). It is
difficult to predict, from the data currently available to us, when our
apple trees will reach the break-even point. We anticipate that, as the
rate they are progressing and with the best possible combination, that is,
'Mcintosh' or 'Spartan' on 'Ottawa 3', planted at high density with the
slender bell system, by the 6 th season we shall completely cancel out

19

the initial debt of 16 342 $ per hectare which it cost to establish and
maintain this system to 1979. In short, production from these trees will
have to rise from 9220 kg/ha to approximately 40 000 kg/ha in 1981.
Certainly, the free-growing trees have been the cheapest to establish and
maintain, but it does not appear that they will be the most profitable.
Some apple growers using the "slender bell" system and high-density
planting have informed us that their apple trees have reached the break-
even point in their 6th season. Some, according to our crop estimates,
have produced, with their fifth - and sixth-season dwarf apple trees,
between 30 000 and 45 000 kg/ha from "slender-bell" ' Spartan ', 'Mcintosh' ,
'Lobo' and 'Red Delicious' cultivars planted at 2 000 to 3 000 trees per
hectare. At this rate, if it is true that the Quebec apple grower must
produce 20 000 bushels of apples in 1980 in order to earn a satisfactory
income, he would need only 20 acres (8,1 hectares) of "slender bell" apple
trees planted at high density to earn such an income by the 6 th or 7th
season.

As regards Quebec's production of pears, plums and cherries, our production
volume has been so low, at least in recent decades, that statistical
surveys do not even mention these crops. However, in 1976, per capita
consumption in Quebec was 7.2 lbs of pears, 2.2 lbs of plums and 1.9 lbs
of cherries (sweet and sour), as compared to 41 lbs of apples. Our market
could thus absorb a good volume of locally produced pears, plums and
cherries, provided the fruit is of satisfactory quality.

Under our climatic conditions, the pear cultivars which could supply the
local market with fruit which is competitive in terms of production and
quality (PI. Ill, figs.b, c and d) are 'Clapp's Favourite', 'Flemish
Beauty', 'Beurree d'Anjou' and 'Miney'. While 'Bartlett' is a better
known cultivar in this province, it is a much more uncertain crop since
the tree is sensitive to freezing and to bacterial fire blight.

As regards plums, the hardy cultivars most likely to find buyers on the
local market are 'Mount Royal', 'Reine Claude de Montmorency' and

20

'Damas Bleue'*. Many other cultivars could become commercially acceptable
since they have produced good yields and quality fruit in Quebec (PI. Ill,
figs e, f and g) . A bulletin on plum growing in Quebec is currently being
prepared at the Saint-Jean Research Station; it will contain further
information on this subject.

We are still far from commercial production of sweet and sour cherries
since these crops, particularly sweet cherries, are very marginal. However,
the production of sour cherries could be intensified in the Lower St
Lawrence and even in other areas where it currently exists in an ambryonic
state and where 'Montmorency', 'Meteor' and 'North Star' cultivars have
proven to be well adapted (PI. Ill, fig. a). Since competition in the area
of sour cherry production in North America is very strong, a serious
study of the potential market for this fruit in Quebec is essential before
we recommend the establishment of commercial orchards.

* note that 'Damas Bleue' , a selection of 'Damson', has a higher quality
than most plums of the 'Damson' series.

21

Appendix

Questions and answers on slides shown at the Amove pavilion August 21, 1980

Q. In the apple cultivars used in Quebec, what type of fruiting habits do
we encounter ?

A. The fruiting habits which we find are:

a) Type I Spur types (PI. I, figs, a and b)

b) Type II 'Mcintosh' and 'Spartan' types (PI. I, f i?»s. c and d)

c) Type III 'Empire' and 'Golden Delicious' types (PI. I, fig. e)

d) Type IV 'Cortland' and 'Red Haralson' types (PI. I, figs, f and g)
These types correspond more or less to those described by Mr. Lespinasse.
Because of the way in which the fruit spurs are arranged in the branches
of each type of tree, they require four different types of orchard
management (pruning and training) .

Q. In Quebec, is it more important to drain orchard soils for dwarf apple
trees than for standard size trees ?

A. Because of the heavy precipitation in the form of snow and rain, it is
absolutely essential to provide good drainage for orchard soils in
Quebec and particularly for dwarf apple trees, since with these trees
the damage potential from successive freezing and thawing of the roots
of the tree is a much greater problem when the soil is waterlogged.
Since dwarf apple trees have a relatively shallow and undeveloped root
system, they are often more subject to root asphyxiation as a result
of excess surface water (PI. II, rig. a) .

Q. Is it necessary to irrigate dwarf apple trees ?

A. Apple orchards in Quebec receive heavy precipitation each year but
unfortunately this precipitation is not uniformly distributed. As a
result, in the great majority of cases, irrigation is necessary, at

22

least during the first few years; the root system of young apple trees
is undeveloped and incapable of locating the soil water reserves,
which, during dry periods, may be fairly deep. It is important to note
that the physiological balance of a dwarf apple tree is much easier to
maintain when irrigation is used, and therefore the trees bear sooner
and more heavily. In addition, some new cultivars, such as 'Spartan',
'Empire' and 'Red Haralson', require the use of an irrigation system
if they are to produce large fruit (PI. II, fig. b).

Q. Should we avoid planting dwarf apple trees because, in our climate, the
branches of the young trees are often cracked or broken by ice, snow
and freezing rain ?

A. Certainly branch damage by ice, snow and freezing rain is a problem in
Quebec but, in general, it is not very extensive. Then too, even
standard apple trees, when they are young, can be damaged by ice, snow
and freezing rain. To avoid this difficulty, it is a good idea to use
good supports or a strong bracing system. Trees with little or no
support are much more seriously affected by this kind of mechanical
damage. A careful apple grower, when a thaw occurs during the winter,
will clear any soft snow from the branches of the apple trees. Once
this snow has hardened, it is impossible to free the branches. In
addition, when the melting snow freezes, it puts a great deal of
pressure on the branches at the crotch. Another phenomenon may also
occur in the spring when the snow melts, leaving an empty space below
the layer of ice which surrounds the branches of the apple tree. When
this happens, the weight of the ice, which does not melt as quickly
as the snow, may cause the branches to bend and crack (PI. II, fig. e).

Q. Is damage caused by field voles and deer more of a problem with dwarf
apple trees ?

A. Given the high density and small size of apple trees in new plantings,
they are certainly much more vulnerable to damage from these two pests
It is therefore important to protect the apple trees from them.

23

Q. Are dwarf apple trees more sensitive to bacterial fire blight than
standard size apple trees ?

A. Bacterial fire blight is no more of a problem with dwarf apple trees

than with standard trees so long as nitrate the fertilizers are not used
to excess, extremely sensitive cultivars are avoided ('Yellow
Transparent', 'St Lawrence', etc.) and sources of contamination are
eliminated. Bacterial fire blight can be spread from one source of
infection by summer pruning, which is used on dwarf apple trees as well
as standard size apple trees.

Q. Is plum growing feasible in Quebec despite the diseases which affect
this crop ?

A. Despite the presence of black knot (Dihotryon morbosum) _, crown gall
( Agvobac terivon tumefaaiens) and various virus diseases, plum growing
is possible in Quebec. Precautions can now be taken against these
diseases. A bulletin currently being prepared at the Saint-Jean
Research Station deals with plum growing in Quebec and with methods
of controlling these diseases.

Q. How can you prevent scion-rooting with a dwarfing rootstock ?

A. Scion-rooting, that is, the formation of roots from the scion, can be
avoided when planting the apple tree by placing the zone of the graft
at least 10 centimetres above ground level (PI. II, fip.c). If the
graft point is accidentally placed below ground level and roots have
begun to develop, these roots must be cut as soon as possible and the
graft area completely exposed. If they are not removed, the scion
roots will completely kill the dwarfing rootstock within one or two
years (PI. II, fig. c).

Q. Is weeding important around a dwarf apple tree ?

24
A. In our experimental plots at Frelighsburg, we have observed that where

weeds have been allowed to grow near the trunks of young apple trees,

they have developed very poorly and have not even begun to fruit by

their fourth season. However, in the same experimental plots where

we have completely cleared the soil by means of chemical weed

treatments, for the entire growing season or for part of it, that is,

until mid-August, the development of the trees in both cases has been

2 to 3 times better than that of the unweeded apple trees and production

has ranged from 5 to 12 kilograms of fruit per tree for 'Mcintosh',

'Jerseymac' and 'Red Delicious' cultivars.

Q. Is there any way of eliminating burr knots on certain apple rootstocks ?

A. There has been relatively little research in this area. However, Dr.
C.G. Forshey and Mr. F. McNicholas, in eastern New York State, have
found that applications of 1 % naphthaleneacetic acid (NAA) have
prevented the development of burr knots on 'M 26' rootstocks (PI. II,
fig.d). More details on burr knots were given previously in the section
dealing with 'Mailing 26'.

Q. Is the south west injury a problem with young dwarf apple trees in
Quebec ?

The south west injury or 'sunscald' is often a very serious problem
with young apple trees in Quebec. To prevent this difficulty, we
advise placing the supports on the southwest side of the tree during
planting, or painting the trunk of the apple tree with a mixture of
exterior white latex-type paint diluted with 2 quarts of water per
gallon, to which 2 lbs of Thiram (75 % WP) in the form of absorbent
powder have been added. The Thiram acts as a repellent against field
mice (field voles) .

Q. What are the most common deficiencies affecting young dwarf apple
trees in Quebec ?

25

A. The south west injure or ' sunscald' is often a very serious problem
with young apple trees in Quebec. To prevent this difficulty, we
advise placing the supports on the southwest side of the tree during
planting, or painting the trunk of the apple tree with a mixture of
interior or exterior white latex-type paint of the lower quality grade
diluted with 2 quarts of water per gallon, to which 2 lbs of Thiram (75%
W.P.) in the form of absorbent powder have been added. The Thiram
acts as a repellent against field mice (field voles) .
N.B. The expensive high quality latex paint may content a mildewcide
(alkyl, alkyd etc.) which is phytotoxic. Avoid using these for-
mulations on fruit trees.

Q. What are the most common deficiencies affecting young dwarf apple
tree in Quebec?

A. In Quebec, magnesium and boron deficiencies are very common (PI. II,
Figs, h, i) . Occasionally there is a calcium deficiency. Consult the
Guide de la Culture du Pommier du Quebec (Guide to apple growing in
Quebec) for more information on this subject (Publication 333, Quebec
Department of Agriculture Agdex 211/20).

Q. Should you use a windbreak to protect new plantings of dwarf apple
trees in Quebec?

A. The use of a windbreak is essential in Quebec apple orchards. The
windbreak should be on the west side of the orchard, towards the
prevailing wind. However, apple trees should not be planted too
close to the windbreak where the snow which accumulates during our
winters will soon break the branches of the apple trees. A good
windbreak could be composed of a row of deciduous trees and a row of
evergreens planted behind them in a staggered arrangement.

26
Literature cited

1 ANON. 1978. Coup d'oeil sur l'agro-alimentaire (Survey of food crops).
Agriculture Quebec. Service des etudes economiques, 334 pp, Fruits

P. 258.

2 BLAIR, D.S. 1954. Plums for cold areas of Eastern Canada. Can Dep Agr
Pub 849, 14 pp.

3 DAVIS, M.B.; D.S. Blair and H.B. Cannon. 1934-1948. Canada Dept Agr.Div
Hort Progr Rept, pp 5-14.

4 FISHER, D.V. 1969. Capitalization at the break-even point for a high
density and low density apple orchard. Report of the C D A Res Stn,
Summerland, B.C.

5 GARON, J., and F. Ouellet. 1978. Reorientation de lf Industrie Pomicole
au Quebec (Reorientation of the apple growing industry in Quebec) .
Programme Agricole 03, Element 02, Service des productions vegetales.
Agriculture Quebec, 2 pp.

6 GRANGER, R.L.,1972. Hints on the use of apple rootstocks. Meeting on
Apple Orchard Management (held in Ottawa in November) .

7 GRANGER, R.L. 1977. Problems and progress with high density apple
orchards in Quebec, p 21 in Hort Res Inst of Ont , Vineland Station,
Report on workshop on Apple Management, August 17-19, 73 pp.

8 GRANGER, R.L.; G. Rousselle and M. Lareau. 1974. L' Ottawa 3, le Mailing
9 et le Mailing 26 en tant que porte-gref f es et tiges intermediaires

de pommier (Ottawa 3, Mailing 9 and Mailing 26 as rootstocks and
interstocks in apple trees). Quebec Horticole, pp 12-16.

9 HUTCHINSON, A. 1964. Rootstocks for tree fruits. Hort Exp Stn,
Vineland, Ont. Dept of Agr Pub 334, 18 pp.

10 HUTCHINSON, A., and E. Andersen. 1976. Compact apple orchard experiments,
management, costs and returns the first 5 years. Paper given at the
International Dwarf Fruit Tree Association, Michigan.

11 LAPINS, K. 1963. Cold hardiness of rootstocks and f ramebuilders for
tree fruits. Res Stn Summerland.

12 LORD, W.J., and J. Costante. 1977. Establishment and management of
compact apple trees. Coop Ext Service, Univ of Mass. USDA and County
Ext Serv Coop, 32 pp.

13 MARGOLIN, A.F. 1951. Dwarf apple trees in the Moscow region (in Russian).
Sad i Ogorod 12: 5-7 1950. Plant Breeding abstracts 21: 1364.

14 MILLER, S.R. 1976. Economics involved in apple bed plantings. Report
of the Smithfield, Ontario Research Station, 14 pp.

27

15 NORTON, R.L. 1971. What you must know about high density plantings.
Go from red to black. July issue of the Am Fruit Grower, pp 10-14.

16 ROUSSELLE, G.L.; R.L. Granger; C.N. Fortin and S. Riendeau. 1975-76.
Resume des recherches en cultures fruitieres - Station de Recherches
de Saint-Jean (Summary of research on fruit growing - Saint-Jean
Research Station). Vols 4 and 5, p 33.

17 SMIRNOV, V.F. 1960. Cultivation of dwarf fruit trees (in Russian).
Gos Izd Selskokhoz Liter, Moscow, 4th ed.

18 TAPER, CD. 1979. Personal communication. Re: progress report on the
performance of dwarf and semi-dwarf apple trees at Macdonald
College.

19 TUKEY, H.B. 1964. Dwarfed Fruit Trees. Mich State University. The
Macmillan Co, New York. Textbook, 562 pp.

20 TUKEY, R.L. 1971. Proc BC Fruit Growers Association. Hort Forum,
35 pp.

21 WATKINS, R. 1968. Summary of results on some of the most promising
Ottawa clonal apple rootstocks with Mailing and Mailing Merton
rootstocks for comparison, report of Jan 11.

Plate I

Fruiting habits and forms of apple trees in Quebec

a. 'MorSpur Mcintosh' /'M Robusta 5', 8th season

b. Branches of 'Mac Spur Mcintosh'

c. 'Imperial Allred Mcintosh' / 'Ott 3', 4th season

d. ' Spartan' /'M 26', Ath season

e. 'Empire' /'Ott 8', 8th season

f. 'Red Haralson' /'Ott 8*, 8th season

g. ' Cortland '/'M 9', 22nd season

h. 'Imperial Allred Mcintosh' / 'Ott 3', "slender bell" training system,

4th season
i. 'Golden Delicious '/ 'M 9', "Van Roechoudt palmette" training system,

6th season
j. ' Spartan' / 'Ott 3', "oblique palmette" training system, 4th season
k. 'Imperial Allred Mcintosh' / 'Ott 3', "free-growing" tree

Plate II

Some anomalies or problems in high-density orchards in Quebec

a. Poor surface drainage, June

b. Feeder, drip irrigation system

c. Scion-rooting of an 'Imperial Allred Mcintosh' /'M 26' apple tree

d. Burr knots on 'M 26'

e. Broken branches on a 'Mcintosh '/ 'M 9' after its 15th season

f. Free-standing 'Spartan'/'M 9' apple tree

g. Leader bending under weight of apples because tree's support is
too short

h. Magnesium deficiency
i. Boron deficiency

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Plate III

Cherries, pears, plums and crown gall

a. 'Montmorency' sour cherries

b. 'Clapp's Favourite' pears

c. Pear tree, cultivar 'Clapp's Favourite'

d. 'Miney' pears

e. 'Early Italian' plums

f. 'Kahinta' plum

g. 'Kahinta' plum tree, 8th season

h. Crown gall on roots of 'Brompton' plum trees

Ill

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AGRICULTURE CANADA

3 JUIN 1986

Bibiiotheque
Complexe Guy Favreau

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