What is it?
The GDC is a form of cultivation of the vine, also known as Double Curtain, which simply refers to the Cortina, which is a system that allows you to completely mechanized pruning and harvesting, and that is suitable for plants with buds and fertile upright varieties. The Cortina is formed by a simple horizontal cordon placed at 120, 150 cm from the soil that supports a single thread of mobile while the GDC follows the same features allowing the splitting of the cord in two, three wires that are raised even to 170 cm from the ground. In this way, the vegetation may fall down while maintaining its strength and allow a good illumination of the bunch.
Breeding in GDC, like other systems, to promote optimal performance in production and keep the quality of the fruits of the plant and must be performed with specific climatic conditions, soil, the variety of lives and structures that support the plant itself . The distance between rows should be from 3.50 to 4 meters when using the tractor for orchards, and if you use a standard tractor, the distance should be between 4 to 4.50 meters. The distance along the row of screws, must be less than one meter (80 cm) for vigorous varieties, while the weak must not exceed half a meter. The planting density (the number of vines per hectare) must be between 2777 and 5714. The parameters differ according to region. Those shown are suitable for vineyards of Northern Italy. In other areas, for example, on the basis of experimental studies, the distance in the row should be included in a -1.50 meters.
The GDC system allows the mechanization of harvesting and pruning ensures high output and requires a low water availability. As mentioned in the first paragraph, also allows you to maintain the vigor of the plant and promotes good lighting of the bunch. Used in the United States until the late '70s, the GDC (Geneve Double Curtain), was then circulated in Italy where they were introduced of amendments to the initial structure of the farming system to increase the use of machines for pruning and the harvest. The grape harvesting machines, in fact, in the GDC, the shaking can operate vertically allowing a smaller loss of juice and a better quality product than the horizontal one. In the GDC system was designed according to modern canons of cultivation, the two strings to create a production side up, sunny, while the vegetation of the shoots, derived from the spurs, falls down because it is not supported by support wires.
GDC or Double Curtain system does not allow a high density of the system that otherwise would affect the vigor of the plant, the latter in the GDC, however, remains at an average level. The most important drawback is the cost of the same plant that is quite high. The equipment necessary for farming GDC are, in fact, different in type and number of components. The GDC will need: self-supporting arms 375, 140 cm long with its support plate, galvanized steel poles 420 40 x 35, 35 end posts always galvanized 55x50, 35 arms of the head; 940 pounds of wire coiled triple-dip galvanizing number 22, 190 kg of steel wire number 18-to-use triple-galvanized screws for vegetation, 35 anchors, 125 aprivegetazione for combing the semi-shoots.
To take full advantage of the GDC materials used must be of good quality and it is this aspect to drive up the cost of the system. The wires and poles must be sufficiently strong and durable to support the vines that have significant size. The choice of the weakest material costs could tip even further because of the need for constant substitutions that may damage the quality of the product. The choice, in the first instance, of high quality materials, will offset the initial costs of the system with the benefit of high production and totally mechanized.
The GDC has found application in the United States since 1960, the year of its introduction to the method developed by Professor Nelson Shaulis, of Pennsylvania who tested at the Geneva Experiment Station in New York, hence the name Double Curtain Geneve, or Double Curtain Geneva, abbreviated as GDC. In 1980 we have introduced a variant of the GDC, said Pound, edited by Dr Alain Carbonneau, Professor of Viticulture at Montpellier. The system Lira, compared to GDC classic, allowing a considerable improvement of the microclimate of vegetation that is exposed to less shading of leaves and fruits. The two cords are grown on two parallel wires, fruiting takes place up and then turn down taking the shape of the Lira. It seems that this variant will facilitate even better pruning