Couderc 3306

History of Origin and Economic Significance

The grape rootstock Couderc 3306 is an interspecific hybrid obtained in France in 1881 by the well-known scientist and breeder Georges Couderc by crossing the parental forms Vitis riparia and Vitis rupestris. The variety was created for areas of phylloxera-infested viticulture and became widespread in regions with cool climates and humid soil conditions. In the commercial assortment of Soviet viticulture, the rootstock Couderc 3306 occupied limited areas: according to the 1960 census in Moldavia, it accounted for about 0.4% of mother vines, and it was also found in the mother vineyards of Ukraine and the Caucasian republics. The main advantage possessed by the rootstock variety Couderc 3306 is its ability to grow successfully in excessively wet (but not swampy) areas, where other Riparia × Rupestris hybrids demonstrate inhibition. The variety Couderc 3306 has good biological affinity with most European grape varieties, providing grafted vines with moderate vigor, early ripening of the harvest, and good sugar accumulation in the berries.

Soil Recommendations and Resistance to Environmental Factors

Based on long-term trials by viticultural institutes, it has been established that the rootstock Couderc 3306 is strictly recommended for deep, cold, plain soils possessing a sufficient natural moisture reserve. This rootstock variety absolutely poorly tolerates dry and arid lands, reacting to moisture deficiency with a sharp slowdown in growth and a decrease in the yield of marketable canes. The drought resistance of the variety is rated as low. The carbonate resistance of the hybrid is low: the rootstock Couderc 3306 withstands an active calcium content in the soil solution of only up to 11% according to the Galet scale. When this threshold is exceeded on carbonate soils, the bushes are affected by lime-induced chlorosis, which causes yellowing of the leaves, a drop in the yield of the grafted scion, and subsequent dieback of the shoots. The frost resistance of the root system is high and stands at the level of the parental form Riparia Gloire.

Morphological Description of the Rootstock Variety Couderc 3306

The botanical characteristics of the rootstock are described based on materials from the ampelographic collections of research institutions:

• Young shoot (tip): The tip of the young shoot is half-open, features intense grape-purple (anthocyanin) edging, and is covered with dense, bristly pubescence. Young leaves are small, almost entire, of intense green color with a strong wine-red or bronze tint.
• Mature leaf: The leaves are of medium size or small, round-cordate in shape, and practically entire. The leaf blade is flat, smooth on the upper side, and dark green. The main veins at the very base are intensely colored a crimson-red. On the lower side of the blade, a distinct, stiff, bristly pubescence is recorded, localized primarily along the veins of the first and second orders. The petiole sinus is open, brace-shaped, or widely V-shaped.
• Teeth: Saw-toothed, relatively large, sharp, with straight margins and well-visible light points at the apexes.
• Petiole: Equal in length to the median vein or slightly shorter, intensely colored a dark red, and covered with short, stiff bristles across the entire surface.
• Flower: Male flower type. Inflorescences are small and develop in large numbers, but do not form berries.
• Annual shoot: The cane is characterized by medium thickness and moderate vigor of the bush. The coloration of the bark of the annual shoot is dark brown or brownish-red, without a distinct gray coating. The internodes are of medium length (11-13 cm). The surface of the shoot is smooth and round in cross-section. The nodes are colored darker than the internodes, and the eyes (buds) are small and conical in shape.

Features of Agricultural Practices in Nursery Management

The rootstock variety Couderc 3306 is characterized by a medium capacity for lateral shoot formation, which favorably distinguishes it from the rootstock 101-14 and reduces total labor costs for conducting green operations in mother vineyards. The ripening of the shoots by the end of the vegetative period is high, amounting to 85-90% of the total growth length, and the wood forms dense with a small volume of pith. In mother vineyards, the variety Couderc 3306 provides a stable yield of cuttings. The cuttings possess a high regeneration capacity, very easily form callus, and root well in commercial nurseries, guaranteeing a high yield of first-grade saplings. The disadvantages of the variety include its increased susceptibility to the foliar (gall) form of phylloxera, as well as the high vulnerability of the shoots to anthracnose and melanosis, due to which the mother vineyards of the grape rootstock Couderc 3306 require regular preventive treatments with fungicides.