Frontenac gris

Grapevine

Variety Description

Variety used for comparison: 'Frontenac'

Summary: The young shoot tip of 'Frontenac gris' has no anthocyanin colouration whereas that of 'Frontenac' is of weak intensity and distributed in a striped pattern. The ventral side of the shoot internode is green with red stripes for 'Frontenac gris' whereas the ventral side of the shoot internode is red for 'Frontenac'. 'Frontenac gris' has berries with red-grey skin and colourless flesh whereas 'Frontenac' has berries with blue-black skin and coloured flesh. 'Frontenac gris' berries produce a non-pigmented juice whereas those of 'Frontenac' produce a pigmented juice.

Description:

PLANT: hardy to extremely hardy winter survival

YOUNG SHOOT TIP: enclosed by small leaves, no anthocyanin colouration, none or very sparse prostrate and erect hairs
SHOOT: dorsal side of nodes and internodes are green, ventral side of nodes is red, ventral side of internodes is green with red stripes, absent or very weak intensity of anthocyanin colouration of buds, erect to semi-erect attitude
WOODY SHOOTS: circular in cross-section, striate surface, yellowish brown, no lenticels, absent or very sparse erect hairs on nodes and internodes, time of bud burst is mid-season
TENDRILS: subcontinuous or continuous, short to medium length

YOUNG LEAF: upper side light copper-red, absent to weak intensity of anthocyanin colouration, absent or very sparse prostrate and erect hairs between veins, sparse prostrate hairs on main veins, absent or very sparse erect hairs on main veins
MATURE LEAF: medium to long, pentagonal in shape, three to five lobes, medium green upper side, flat in profile, absent or very weak blistering on upper side, no goffering on upper side between secondary and tertiary veins, no undulation of leaf blade between main and lateral veins, length to width ratio of teeth is medium, both sides of teeth are rectilinear, very open petiole sinus, u-shaped base of petiole sinus, upper leaf sinus is open, base of upper leaf sinus is u-shaped, absent or very weak intensity of anthocyanin colouration of the main veins on upper and lower sides, none to very sparse prostrate and erect hairs between veins and on main veins on lower and upper sides, short to medium length petiole, absent or very sparse prostrate and erect hairs on petiole

FLOWER: hermaphrodite type

FRUIT CLUSTER: medium length, medium density (densely distributed berries, pedicels not visible), very low to low weight, few to medium number of berries per cluster, short to medium length peduncle, medium lignification of peduncle
BERRY: begin ripening late in season, short, very low to low weight, uniform size, roundish, circular in cross-section, non-pigmented juice, neutral flavour, very short pedicel, easy separation from pedicel
BERRY SKIN: red-gray, uniform colour, medium bloom, thin
BERRY FLESH: colourless, juicy, medium firmness
SEEDS: hilum visible, fully developed

Origin & Breeding History: 'Frontenac gris' was discovered in 1992 as a single cane sport (a spontaneous mutation), bearing gray coloured fruit of the variety 'Frontenac' at the University of Minnesota Horticultural Research Centre located near Excelsior, Minnesota, USA. From 1995 to 1999, eight vines of 'Frontenac gris' were asexually propagated by hardwood cuttings and observed until 2002. It was determined that the plants derived from the cuttings (including their flowers and fruits) were indistinguishable in appearance from the original 'Frontenac gris' cane. The initial selection of 'Frontenac gris' was based on its well-branched habit, large flowers and flowering under short days. Additional selection criteria included vigour, reliable cutting propagation and cutting stability.

Tests & Trials: The trial for 'Frontenac gris' was conducted in a production vineyard in St. Paul d'Abbotsford, Quebec in 2013. A total of thirty-five vines per variety were planted in 2007. The vines were spaced 1.2 metres apart within a row with spacing of 2.5 metres between rows. The vines began producing fruit in 2010. Ten vines of each variety were examined.

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Grapevine: 'Frontenac gris' (left) with reference variety 'Frontenac' (right).