Couderc 3309

Origin History and Economic Significance

The rootstock grape variety Riparia × Rupestris 3309 was bred in France in 1882 by breeder Georges Couderc by crossing Riparia Tomento with Rupestris Martin. The distribution of the variety across viticultural regions occurred simultaneously with the 101-14 rootstock. The economic significance of the rootstock lies in ensuring the longevity and stable productivity of grafted vineyards. Grafted vines demonstrate good growth for many years. The yield of first-rate saplings in the nursery is high, reaching 60% or more.

A significant biological disadvantage of the variety is its high tendency to form lateral shoots, water sprouts from the vine head, and lateral buds on main stems, which increases manual labor costs for green operations and served as a reason for limiting the establishment of new mother plantations.

Ampelographic Description of the Riparia × Rupestris 3309 Variety

• Young shoot (tip): The tip of the young shoot is smooth, glossy, light green, with a slight bronze tint. Young leaves are bronzed, shiny, completely smooth on the upper side, and bear sparse stiff hairs along the veins on the lower side. The veins of young leaves are reddish. Stipules are small and dry out rapidly. The shoot axis is green, with a reddish tint on the sun-exposed side, smooth, and covered with a faint whitish waxy bloom.
• Formed leaf: Adult leaves are medium-sized, cordate, flat or slightly trough-shaped, with wavy margins. The leaf blade is entire, with large, prominent triangular terminal teeth elongated into a sharp point. The upper surface of the leaf is glossy. The veins are reddish at the petriolar insertion. On the lower side of the leaf, sparse stiff pubescence is present along the veins and in their angles, which almost completely disappears by the end of the growing season.
• Sinuses and petiolar sinus: The petiolar sinus is arrow-shaped (sagittate) with a sharp base, which serves as a key identifying trait of the variety (it can be lyre-shaped in spring). Lateral sinuses are absent or barely indicated.
• Teeth: The teeth at the lobe ends are triangular with a somewhat elongated apex. The teeth along the margin of the leaf blade are quite large, triangular-serrate with weakly convex sides, and widened at the base. The petiole is equal to or shorter than the central vein, glossy, green, with a wine-red tint on the sun-exposed side.
• Flower: The variety develops male flowers. There are five, rarely six stamens. The pistil is completely reduced. Inflorescences are small, compact, conical (resembling Rupestris du Lot), and form on the vines in large numbers. After flowering, the infolrescences dry out completely; no berries or clusters are formed.
• Canes: Mature annual shoots are not thick, round, brown or slightly reddish, with medium internode length and a small pith.

Features of Agricultural Technology of the Riparia × Rupestris 3309 Grape Rootstock

The Riparia × Rupestris 3309 variety is less demanding of soil quality compared to the 101-14 rootstock and can grow successfully on poorer, stony plots. In the Georgian SSR, the variety is recommended primarily for soils with an acidic reaction (pH below 6.8). Tolerance to soil-induced chlorosis is moderate—the rootstock withstands up to 25–30% of total limestone (evaluated with an index of 11 for active calcium on the Drouineau-Galet scale), while being less affected by chlorosis than the 101-14 variety. A disadvantage of the rootstock is its weak resistance to salinity: it suffers more than other rootstock varieties from elevated sodium chloride content in the soil, and in dry years, the rootstock and the vines grafted onto it are affected by fanleaf virus degeneration.

Due to its deeply penetrating, well-developed root system, the rootstock exhibits high resistance to soil moisture deficiency, surpassing the 101-14 variety in drought tolerance. The frost resistance of the roots is high (on par with the 101-14 rootstock). The yield of mother plantations reaches 60,000 to 80,000 half-meter cuttings per hectare under non-irrigated conditions, up to 42,800 meters in Western Georgia, and up to 21,500 meters in Eastern Georgia. Canes mature well by the end of the growing season. Resistance to the root form of phylloxera is high, and the variety is practically completely resistant to downy mildew, requiring no protective spray treatments, but it is heavily affected by the leaf form of phylloxera.