Apple tree named `M9-RN29`

This invention relates to a new and distinct apple tree rootstock clone which is useful as a size controlling rootstock. The new clone originated as a mutation of Malling 9 (M9), an unpatented dwarfing apple rootstock. Standard growing apple cultivars propagated on this new rootstock are approximately 65% of the size of like apple trees growing on seedling rootstocks. Compared to its M9 parent, this new clone produces many more and larger lateral branches, has more sharply serrated leaves which are more pale yellow-green in color. The clone is also more vigorous and produces a large number of rooted plants in a given area of stoolbed.

BACKGROUND AND SUMMARY OF THE INVENTION 
The inventor of the subject plant, Rene Nicolai, was the owner of Rene 
Nicolai Nursery, which propagated and sold Malling Nine (M9) apple tree 
rootstock. Rootstock are propagated by placing plants in a stoolbed which 
encourages root growth and then dividing the resulting roots into 
individual plants. Over the years Mr. Nicolai searched the M9 stoolbeds 
for M9 mutants which were superior to the parent variety in those 
characteristics which are desirable for apple tree rootstock. 
The subject clone was selected in 1967 from a large stoolbed of M9 plants 
that was planted in 1960 at the Rene Nicolai Nursery at Linderstroot, 
22-B-3820 Alken, Belgium. The original source of the plants in the bed was 
the East Malling Research Station in England. Following its selection, the 
clone was assigned a number (RN29) and was propagated for further testing 
and evaluation. 
Since all original M9 rootstocks have been found to be virus infected, RN29 
stocks were subsequently heat-treated by application of dry heat in order 
to obtain virus-free specimens. After heat treatment and subsequent virus 
testing, the new rootstock clone was again exposed to multiplication 
techniques (stooling) followed by continued testing and evaluation. 
Virus-free RN29 progeny plants were expanded into small stoolbed plantings 
at several locations which were planted separately in order to examine the 
new variety's individual characteristics in small semicommercial stoolbed 
sites. Since 1974 nearly 40,000 plants of the subject variety have been 
planted at the following six sites and, in the process, many generations 
of the tree have been produced: 
1. A site at Deveaux, Belgium was planted in the spring of 1974 with 1,875 
plants of the subject clone. 
2. A site at Bordeaux, France was planted in 1977 with 200 plants of the 
subject clone. 
3. A site at Wissenhoeve, Belgium was planted in the spring of 1980 with 
7,644 plants of the subject clone. 
4. A site near St. Truiden, Belgium was planted in the spring of 1982 with 
100 plants of the subject clone. 
5. A site at Henkaenrts, Belgium was planted in the spring of 1986 with 
3,250 plants of the subject clone. 
6. A site at Ephrata, Washington was planted in the spring of 1990 with 
26,000 plants of the subject clone. 
Clone RN29 was subsequently finally selected as a rootstock clone that 
continues to possess growth and rooting characteristics that are 
distinctly different from its M9 parent. 
It distinguished itself in these beds from its M9 parent in the following 
ways: 
1. The subject clone produces many more lateral limbs (feathers) than its 
M9 parent and grows more robustly in the stoolbed (FIGS. 2 and 3, Charts 1 
and 2). Average increases in height of the plants in the stoolbed for the 
RN29 is almost 30% more than for the M9 (FIG. 6, M9; FIG. 7, RN29) and the 
average increase in the numbers of feathers produced is more than 
three-fold. There also occurs a great difference in the average length of 
the individual feathers produced (Chart 2). Because of the more robust 
growth and increased number of limbs produced by the RN29, a two-fold 
difference also occurs in the number of leaves produced per stoolbed plant 
(Chart 2). The number of nodes/shoot and the aver- age individual stem 
circumference were also greater for RN29 due to its more robust growth 
habit. Leaf size (adding the length and width together) and the length of 
the petioles were consistently smaller than the virus-free M9 (Chart 3). 
CHART 1 
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Percent of Layer Plants with Side Limbs (Feathers) 
(Test Stooling Beds at Bordeaux, France) 
Year 
Rootstock Clone 
79/80 80/81 81/82 82/83 
Average 
______________________________________ 
M9 (virus-free) 
13 8 25 0 11.5 
RN8 8 6 13 0 6.8 
RN19 41 32 44 19 34.0 
RN29 39 22 35 15 27.8 
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CHART 2 
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Growth Characteristics 
(Test Stooling Beds at Ephrata, Washington) 
Length Number Number Length 
Number 
Root- 
of of of of of Circumference 
stock 
Shoot Nodes/ Spura/ Spur Leaves/ 
of Stem 
Clone 
(cm) Shoot Shoot (cm) Shoots 
(cm) 
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H9 66.80* 39.20 3.00 1.50 53.00 3.24 
RN8 62.10 42.10 1.80 1.20 57.20 3.80 
RN19 78.20 41.00 18.60 8.60 88.30 3.51 
RN29 86.20 45.60 21.40 10.30 100.00 
3.54 
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*All numbers shown are the average of 100 plants selected at random. 
CHART 3 
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Leaf Size and Respective Petiole 
Length of Respective Rootstock 
(Test Stooling Beds at Bordeaux, France) 
Rootstock 
Length, L 
Width, W L + W Length of 
Clone (mm) (mm) (mm) Petiole 
______________________________________ 
M9 101.7 63.8 165.5 32.5 
(virus free) 
RN8 98.8 73.6 172.4 34.0 
RN19 91.4 60.0 151.4 30.8 
RN29 85.5 57.1 142.6 28.5 
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2. The subject clone has the ability to produce many more rooted daughter 
plants per mother plant (FIG. 1) and per meter of stoolbed row than its M9 
parent (Charts 4, 5 and 6). Data collected at the Deveaux, Belgium test 
site shows a two-fold increase in rooting ability and in the number of 
rooted plants harvested (Charts 1 and 2) and at a test site at Bordeaux, 
France a three-and-one-half-fold increase is demonstrated after five years 
in the stoolbed (Chart 6). 
CHART 4 
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RN29 Stoolbed Production (Deveaux, Belgium) 
______________________________________ 
No. Mother Plants - 1,875 
Length of Bed (m) - 6,215 
Year 
Grade (mm) 
82/83 83/84 84/85 85/86 86/87 
______________________________________ 
10/12 1,700 900 1,450 3,050 2,500 
8/10 0 0 2,100 0 0 
6/10 20,600 16,400 0 0 13,850 
6/8 0 0 13,040 13,500 0 
5/7 0 0 0 0 0 
4/6 11,400 11,200 17,200 11,400 20,100 
04 0 3,100 0 4,900 1,050 
#2s 4,500 3,900 4,000 4,400 7,900 
Totals 38,200 35,500 37,790 37,250 45,400 
Per Mother 
20.37 18.93 20.15 19.87 24.21 
Plant 
Per Meter 
61.12 56.80 60.46 59.60 72.64 
______________________________________ 
Year 
Grade (mm) 
87/88 88/89 89/90 90/91 
______________________________________ 
10/12 2,100 0 1,200 1,650 
8/10 5,150 7,050 6,050 0 
6/10 0 0 0 20,900 
6/8 14,200 15,200 13,800 0 
5/7 0 0 0 0 
4/6 1,400 14,500 15,900 14,100 
04 0 0 0 0 
#2s 7,500 4,300 10,800 4,700 
Average 
Totals 30,350 41,050 47,750 41,350 82/91 
Per Mother 
16.19 21.89 25.47 22.05 21.02 
Plant 
Per Meter 
48.56 65.68 76.40 66.16 63.05 
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CHART 5 
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M9(Virus-Free) Stoolbed Production (Deveaux, Belgium) 
______________________________________ 
No. Mother Plants - 561 
Length of Bed (m) - 187 
Year 
Grade (mm) 
82/83 83/84 84/85 85/86 86/87 
______________________________________ 
10/12 225 100 250 750 464 
8/10 0 0 450 0 0 
6/10 4,150 2,950 0 2,350 2,200 
6/8 0 0 3,400 0 0 
5/7 0 0 0 0 0 
4/6 1,800 1,600 2,200 1,600 3,000 
04 0 300 0 0 0 
#2s 700 800 500 500 1,400 
Totals 6,875 5,750 6,800 5,200 7,064 
Per Mother 
12.25 10.25 12.12 9.27 12.59 
Plant 
Per Meter 
36.76 30.75 36.36 27.81 37.78 
______________________________________ 
Year 
Grade (mm) 
87/88 88/89 89/90 90/91 
______________________________________ 
10/12 75 -- -- -- 
8/10 450 -- -- -- 
6/10 0 -- -- -- 
6/8 2,700 -- -- -- 
5/7 0 -- -- -- 
4/6 2,200 -- -- -- 
04 0 -- -- -- 
#2s 400 -- -- -- 
Average 
Totals 5,825 -- -- -- 82/91 
Per Mother 
10.38 -- -- -- 11.14 
Plant 
Per Meter 
31.15 -- -- -- 33.43 
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CHART 6 
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Average Number of Plants Per Stoolbed Mother Plant 
(Test Stooling Beds at Bordeaux, France) 
Year Planted and Age 
Rootstock 79/80 80/81 81/82 82/83 
Clone 2-Yr 3-Yr 4-Yr 5-Yr Average 
______________________________________ 
M9 (virus-free) 
1.2 2.6 .5 4.0 8.3 
RN8 2.1 3.9 3.8 6.4 16.2 
RN19 2.6 4.4 6.5 9.1 22.6 
RN29 4.4 5.6 5.7 11.3 27.0 
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3. Small differences in leaf color and structure have also been noticed. 
Leaf color of the subject clone is a pale yellow-green as compared to M9's 
darker green color (FIG. 5) RN29 is also characterized with leaves which 
exhibit smaller and sharper serrations than does its M9 parent (FIG. 4). 
4. The lack of blooming characteristics of RN29 is very pronounced and in 
this respect differs distinctly from its M9 parent. The lack of any bloom 
produced on RN29 two-year-old line-out stocks was contrasted with the 
amount exhibited by the M9 parent (chart 7). 
CHART 7 
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Bloom Characteristics 
(Research Station at Gorsum, Belgium - 1985) 
% of Rootstocks With Bloom 
Rootstock Clone 
(1 Year From Stoolbed) 
______________________________________ 
RN8 29 
RN19 4 
RN29 0 
M9 (virus-free) 
15 
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DESCRIPTION OF VEGETATIVE CHARACTERISTICS 
The following is a detailed description of the new apple rootstocks growth 
characteristics based on the stoolbed plants grown at the six test sites 
described above. Colors of the leaves and shoots are based on their 
appearance at the sites where grown. In those instances where a precise 
color assessment can be made, reference is to the Munsell Limit Color 
Cascade Table. In other instances, general color terms are used in 
accordance with the ordinary dictionary significance. 
General habit: 
Strength of growth.--Vigorous, stiff. 
Habit.--Upright. 
Branching.--Many, flexible, willowy. 
Vegetative Shoots: 
Bark color.--Greenish-brown (22-14). 
Pubescence.--Finely tomentose. 
Lenticels.--Few, inconspicuous, widely spaced, small, yellow-white. 
Leaves: 
Size.--Average, 5.7 cm wide, 8.6 cm long. 
Shape.--Broad elliptic, somewhat asymmetric, wavy. 
Base.--Obtuse, attenuated. 
Apex.--Mucronate. 
Serrations.--Finely serrate at sides, more obtuse margins at base. 
Spacing.--Normal phyllotaxical arrangement for Malus. 
Color.--Pale yellow-green (22-11) with pinkish tips. 
Leaf scars: 
Shape.--Broad V, slightly raised. 
Color.--Dark brown. 
Petioles: 
Shape.--Slender, slightly channeled. 
Length.--Medium, 2.85 cm. 
Color.--Reddish-brown (32-12). 
Pose.--Slight acute angle near tip, mostly horizontal. 
Glands.--None. 
Stipules: 
Size.--Small, 3-5 mm, inconspicuous, some minutely serrated. 
Color.--Yellow-green. 
Pose.--Mostly reposed along petiole. 
Lateral buds: 
Size.--Small. 
Shape.--Flat, angular. 
Color.--Dark brown. 
Pubescence.--Fine hairs, tomentose. 
Apical buds: 
Size.--Larger than lateral buds. 
Shape.--Obtuse. 
Color.--Dark brown. 
Pubescence.--Tomentose. 
Dormant Plant 
Shoots: 
Size.--Stocky, 7.8-12.0 mm in caliper at base, stiff, brittle. 
Bark color.--Dark brown (25-15). 
Pubescence.--Conspicuously pubescent. 
Nodes.--Larger in diameter than internodes with shoulder at each side on 
leaf scar. 
Internodes.--Smooth, regularly spaced. 
Stooling and Root Characteristics 
Rooting and stooling: Multiplies well in stoolbeds, forming strong roots 
along full length of shank. Roots arise from nodes. 
Flower Characteristics 
Flowers: 
Size.--3.5 cm in diameter. 
Color.--White with pinkish streaks toward base. 
Fruit (No commercial value but useful for identification): 
Shape.--Round to slightly oblong. Color.--Red stripes. Size.--4.5 cm in 
diameter, 5.5 cm in length. Flavor.--Bland, tasteless. 
General Characteristics 
Rootsuckering: Slight. 
Size control potential: Size of trees budded on the subject rootstocks will 
vary according to the vigor of the cultivar, condition and type of soil 
and orchard management. "Standard" growing cultivars such as Red and 
Golden Delicious are reduced in size about 65% when compared to trees on 
apple seedling rootstocks. Less vigorous varieties are more reduced in 
size and more vigorous varieties are less reduced in size. 
Dwarfing: Fully dwarfing. 
Precocity: Varies according to variety, most cultivars often flower and set 
fruit the first year in the orchard and thereafter bear fruit each year. 
Compatibility: Graft compatible with all major commercial fruiting 
varieties. 
Root anchorage: Needs support. 
Hardiness: Hardy in most commercial apple growing areas. 
Disease and pest resistance: Average resistance to common diseases and 
pests of apple. Tested and found free of all known virus and virus-like 
diseases to apple.