Apple tree rootstock named ‘G.66’

Abstract

A new and distinct variety of apple tree rootstock Malus domestica x Malus robusta hybrid ‘G.66’ is described herein. The new variety is a productive, yield efficient, semi-dwarfing rootstock that is resistant to fire blight (Erwinia amylovora) and crown rot (Phytophthora cactorum). The ‘G.66’ rootstock is useful in that it can be propagated clonally and used as a rootstock or root system for apple trees as well as for interstems of apple trees.

Claims

1. A new and distinct variety of apple tree named ‘G.66’ as herein described and illustrated.

Description

DESCRIPTION OF THE FIGURES

(1) New apple tree rootstock ‘G.66’ is illustrated by the accompanying photographs. The ages of the trees depicted in the photographs are noted below. The colors shown are as true as can be reasonably obtained by conventional photographic procedures.

(2) FIG. 1 shows dormant shoots (including buds and bark).

(3) FIG. 2 shows abaxial (lower) and adaxial (upper) laminae of leaves.

(4) FIG. 3 shows interior and exterior of fruit and seeds.

(5) FIG. 4 shows a stool propagation bed with fully developed shoots.

(6) FIG. 5 shows micro-shoots obtained by in-vitro propagation.

(7) FIG. 6 shows roots grown in aeroponics.

(8) FIG. 7 shows 5 year old trees grafted on ‘G.66’.

(9) FIG. 8 shows maturing fruit and leaves.

(10) FIG. 9 shows high anthocyanin levels in developing leaves.

DETAILED BOTANICAL DESCRIPTION OF THE INVENTION

(11) The following description of apple tree rootstock ‘G.66’ contains references to color names taken from The Royal Horticultural Society Colour Chart (R.H.S.), 2001 edition. Botanical descriptions follow the Manual of Cultivated Plants (Bailey, 1949). Tree: Habit.—A self-rooted tree of ‘G.66’ is a shrub typically standing about 1.5-2 meters tall by about 2 meters wide when 7 years old. Multiple trunks-shoots can develop from suckers (adventitious shoots arising from surface roots). Canopy can be somewhat spreading. Rootstock liners planted in the nursery stop apical growth mid-season. The apical bud in these plants is pubescent Greyed-Purple (RHS 187A to 187B). Productivity.—In an intermediate trial performed at a research farm (Geneva, N.Y.), the ‘G.66’ rootstock received the cultivar ‘Golden Delicious’ (Not patented) (Malus domestica) as the scion and was compared to the Malus domestica check rootstocks ‘Mailing 9’ (‘M.9 EMLA’; Not patented), ‘Mailing 26’ (‘M.26’; Not patented) and ‘Mailing 7’ (‘M.7’; Not patented). ‘G.66’ was shown to have statistically similar (p≤0.05) yield efficiency (kg yield/cm.sup.2 trunk cross sectional area) than ‘Mailing 9’ and ‘Mailing 26’ rootstocks while featuring the largest cumulative yield. Precocity.—Scion cultivars budded on ‘G.66’ exhibit similar precocity (early bearing induction) as those budded on ‘Mailing 26’. Fertility (fecundity).—The ‘G.66’ plant produces flowers and fruits regularly. Dormant shoots (buds and bark): Dormant mature shoots.—Color: Greyed-Purple (RHS N186A to N186B). Texture: Some pubescence which gradually disappears in older tissues. Size: 30-60 cm long; may have some spines. Diameter: Typical, mature one year dormant shoots have a diameter ranging from 12-22 mm. Axillary buds.—Size: 4-5 mm long and 3 mm wide with pubescence on the apices. Shape: Obtuse, sessile, somewhat protruding and flattened. Texture: Some pubescence. Bark on three-year-old shoots.—Color: Greyed-Purple (RHS 197A). Lenticels: Color: Greyed-Orange (RHS 171B to 171C). Size: 0.3-0.4 mm in diameter. Quantity: 1-2 lenticels per cm.sup.2. Leaves: Mature leaves.—Leaf arrangement: Alternate. Shape: Simple, recurved, oblong-ovate. Size: Length: 110 mm. Width: 60 mm at the widest point. Laminae: Somewhat wavy. Apex: Acuminate. Base: Nearly symmetrical rounded. Margin: Serrated, with about 4 serrations per cm. Upper surface: Color: Green (RHS 141B) with Greyed-Purple (RHS 185B) venations. Texture: Glabrous and translucent. Lower surface: Color: Yellow-Green (RHS 146B) with Greyed-Purple (RHS184C to 184D) hues and venations. Texture: Somewhat pubescent. Venation: Netted. Venation color: Greyed-Purple (RHS184C to 184D) in the larger venations transitioning to Greyed-Red (182D) in smaller veins. Leaf poise: 25°-45° from the shoot, depending on shoot orientation. Stipules:

(12) Length: 8 mm. Width: 2 mm. Color: Green (RHS 141B) to Greyed-Purple (RHS184C to 184D). Petioles: Diameter: 3 mm. Length: 18-25 mm. Texture: Glabrous (smooth). Color: Greyed-Purple (RHS 184A to 184C) depending on low or high exposure to light. Flowers: Habit.—Flowers borne on spurs, shoot terminals, and from lateral buds on growth from previous season. Flower diameter.—40 mm. Fragrance.—None. Buds.—Location: Located on spurs and terminals; are mixed, typically producing a truss of 5 to 6 flowers and one bourse shoot. Pubescence color: Greyed-Green (RHS 196C). Color of scales beneath pubescence: Greyed-Purple (RHS N186A). Shape: Lateral buds are obtuse, sessile and somewhat appressed. Size: Length: 4 mm. Width: 3 mm. Habit: Buds near the base of the shoot of the previous season usually produce 3 to 5 flowers and a single short shoot; mid-shoot buds may have 2-4 flowers; and more distal buds are usually vegetative. Petals.—Size: Length: 25 mm. Width: 18 mm. Shape: Spatulate. Apex: Obtuse. Margin: Smooth. Texture: Smooth. Arrangement: Intermediate. Color: Closed petals: Red (RHS 54A) (Abaxial surface). Opening petals: Flowers undergo a transition as they are opening and colors become less intense. Open petals: Red-Purple (RHS 64D) with Red (RHS 54A) striations in some of the petals (Adaxial surface). Reproductive organs.—Pistils: Length: 6 mm. Color: Red (RHS 52B). Stamens: Length: 4 mm. Color: Red (RHS 52A). Anther color: Greyed-Yellow (RHS 162A). Fruit: Mature fruit.—Size: Height: 35-40 mm. Diameter: 30-35 mm. Shape: Obloid. Color: Orange-Red skin (RHS 30B) with Red (RHS 43B) blush overtones depending on the exposure to the sun. Sepals: Persisting on a protruding calyx. Flesh: Taste: Astringent (not meant for consumption). Color: Orange-Red (RHS 30A to 30D) bleeding from skin and core. Pedicels: Length: 20-27 mm. Diameter: 0.8-1.2 mm. Texture: Glabrous (smooth). Color: Greyed-Purple (RHS 184A to 184C). Seed: Color: Greyed-Red (RHS 179A), translucent. Shape: Tear drop shape. Texture: Glabrous (smooth). Size: Length: 3 mm. Diameter: 4.5 mm at the widest point. Number: Generally five seed per fruit. Disease resistance: As described above, the ‘G.66’ rootstock of the present invention exhibits resistance to fire blight. The percent lesion measured after inoculation of potted liners in the greenhouse using four different strains of E. amylovora was negligible for two of the strains and moderate for the other two, indicating a specific resistance to the bacterium. The ‘G.66’ rootstock, having survived the inoculation with crown and root rot, is also considered resistant to crown and root rots caused by Phytophthora cactorum.