Apple Scion /Rootstock Selection and Planning for Michigan

Apple Scion/Rootstock Selection and Planning for Michigan

R.L. Perry and J. Hull
Dept. of Horticulture
Michigan State University
East Lansing, MI 48824

The training system that a grower selects must be one which best maximizes all the resources in making the enterprise a profitable venture. There are many parts to the orchard system decision "puzzle" (Barritt, 1991) which must fit together in a complementary arrangement to make it work. The most immediate question that must be answered regarding the establishment of a new orchard is spacing. In 1989, we made an initial attempt at trying to simplify the decision making process by considering the most important variables and assigning them values (# codes in parentheses) in a formula. Our experience gained from working with the high density orchards and with new cultivars has encouraged us to revise the 1989 model. More revision in the future will be necessary as we learn more of the technical intricacies of new rootstocks, cultivars, marketing demands and management constraints.

The primary factors affecting spacing include; scion vigor, rootstock vigor, soil type, irrigation, management intensity and the interactions that take place between them. The spacing recommendation in this writing pertains to single row arrangement of trees. Use the on-line form below to calculate in-row tree spacing based on your input:

A. Scion Vigor

Enter the number in parentheses that corresponds with scion vigor:

I. Low vigor spur type varieties (1)

Redchief Del. (Campbell), etc.

II. Medium low vigor spur-type and precocious cultivars (2)

Empire, Idared, Vallee-Spur, Spur-Rome, Spur-Macs, Braeburn, Spur-Red Del. (Starkrimson, Starkspur, Sturdee etc.), Honeycrisp, etc.

III. Medium vigor (3)

Prime Red (Akane), Jonathan, Jonagold, Redcort, Gala, High Early Red Del., Golden Del., Early Red One Red Del., Tydeman's Red, Jonamac, etc.

IV. Vigorous (4)

Rome, Liberty, Sharp Red Del., Imperial Red Del., Lodi, McIntosh, Starking Red Del., Winesap, Paulared, Spartan, Melrose, Jerseymac, Redfree, Cortland, Wealthy, Top Red Del., Red Prince Red Del., Fuji, GingerGold, etc.

V. High vigor (6)

Northern Spy, Granny Smith, Mutsu, Rhode Island Greening, etc.

B. Rootstock Vigor

Enter the number in parentheses that corresponds with selected rootstock vigor:

(0) M.27, P22, G65

(0.5) Mark, M.9 NAKB, Bud.9

(1) M.9 EMLA, PJ2, RN 29

(2) Ottawa 3

(2.5) M.26, Interstem

(3) G.30

(5) M.7

(7) MM. 106

(9) MM. 111

C. Soil Type

Enter the number in parentheses that corresponds with your soil type:

(0) Sandy or gravelly soil to 4 ft. (droughty, no use of rootstocks in vigor code 0-1)

(1) Low fertility sandy loam or shallow soil < 3 ft.

(2) Moderate fertility, loam soil

(3) High fertility, clay loam, with good moisture retention (i.e., well drained but with good moisture in low areas)

D. Irrigation

Enter the number in parentheses that corresponds with your irrigation method:

(0) None

(1) Applied when needed, portable sprinkler etc.

(2) E. pan, trickle (i.e. 'Kenworthy Rule of Thumb,' start watering when growth starts at 1 gal./tree/year of tree age for 200 trees/acre; or 2 gal./tree/year tree age for 100 trees/acre; both up to 12 years of tree age)

(note: irrigation recommended for rootstocks in vigor codes 0-1)

E. Management Intensity

Enter the number in parentheses that corresponds with your anticipated level of management intensity:

(0) High intensity; winter and summer pruning & spread/tie limbs for first six years; staked trees on dwarf rootstocks*

(1) Medium intensity -- winter and summer pruning

(3) Low intensity -- winter pruning only

* For high-density systems, enter the number in parentheses here that corresponds with the following system factors. Otherwise leave as or enter 1.

(0.7) Vertical Axis and HyTec

(0.6) Slender Spindle

(0.4) V-trellis

Finally, enter anticipated tree height in feet:

NOW IN-ROW and ACROSS-ROW Tree Spacing based on above input (assumes North/South row direction):

RESULT: Feet between trees IN-ROW.

RESULT: Feet between trees ACROSS-ROW.

The formula: (assume North/South row direction)

In-row tree spacing =
Scion vigor + Rootstock vigor + Soil type + Irrigation + Management Intensity (*)
* For high density systems multiply In-row tree spacing by system factors
Vertical Axe and Hytec (0.7), Slender Spindle (0.6), V Trellis (0.4).

Row spacing width (minimum distance) = 1.3 x expected or projected tree height
(for East/West row direction = use 1.5)

Example 1: Idared / M.26, sandy (droughty) soil, drip irrigated, on stakes, expect 12 ft. high tree:
In-row tree spacing =(A.) 2 + (B.) 2.5 + (C.) 1 + (D.) 2 + (E.) 0 = 7.5 feet
Row spacing = 1.3 x 12 = 15.6 feet (7.5 x15.6 ft).

Ex. 2: McIntosh / MM.106, sandy soil, no irrigation, low intensity, expect 14 ft. high tree:
In-row tree spacing = 4 + 7 + 0 + 0 + 3= 14 feet
Row spacing = 1.3 x 14 = 18.2 feet (14 x18.2 ft).

Ex. 3: Jonagold / M.9 EMLA, fair vigor soil, drip irrigated, V.Axe, expect 10 ft. high tree:
In-row tree spacing = 3 + 1 + 2 + 2 + 0 = 8 x 0.7 = 5.6 feet
Row spacing = 1.3 x 10 = 13 feet (5.6 x13 ft).

Ex. 4: Empire / Mark, vigorous clay loam soil, drip irrig., slender spindle, expect 8 ft. high tree:
In-row tree spacing = 2 + 1 + 3 + 2 + 0 = 8 x 0.6 = 4.8 feet
Row spacing = 1.3 x 8 = 10.4 feet (4.8 x 10.4 ft).

References

Crassweller, R. M. and P.H. Heinemann and E.G. Rajotte. 1989. An expert system on a microcomputer for determining apple tree spacing. HortScience 24 (1): 148.

Barritt, B. 1991. The Hytec orchard system for apples. Compact Fruit Tree 24: 17-25.