This form of breeding, invented by the ancient Romans and perfected by M. Guyot has a double and simple variant, it has a head and canes. Head refers to the enlarged section on top of the trunk. Fruiting canes are shoots grown in that year on the head of the vine and have a variable length between 7 and 9 buds. The head originates from the natural reaction of the plant to the pruning cuts, it can be shaped like a cone or a goblet depending on the pruning method and must always be kept compact.
In some varieties the head can coincide with a vegetative point, while others need two points to keep the correct distance from the curvature wire. Not all varieties adapt to this training system because of physiology or productivity reasons.
Bilateral management of the head, perfect when there are two fruiting canes or when the grown variety does not guarantee all free buds to sprout. Spurs are fundamental in keeping the head of the plant at the correct distance from the wire.
In order for the cone head to work correctly, the vegetative point must be located in top section of the stem. This position will guarantee lymph flow in the whole peripheral section and will keep the whole gobelet alive. Morphologically it is not a real head but an extension of the constantly growing vegetative point.
Forcing ramification in the head goes against the physiology of the plant. For optimal management of the head, both in ramified and cone head training, the vegetative point must be kept as close as possible to the trunk axis. Ramifying the head instead will bring the vegetative point farther away from the trunk axis and will result in uncovered sections and bundled sections in the leaf wall. Ramification will render plant management much harder, that is, died sections will easily appear in the conductive tissue and will degenerate it fast.
On this vine on breeding, branching is set up to preserve the upward flow of the lymph (follow the flow). This creates a reduced lymphatic flow of the upper area of the head. When the head grows old this section of the plant will more easily decay. This dead wood can not be used by the plant and it is subject to installation of mushrooms.
The more the vine head is close to the roots the more easily the plant will react to the pruning cuts.
The plants in the picture are about fifty years old and the heads, despite having been “tortured” over time, are still vital, with very few dead sections.
With the Guyot method the shoots are curved on the bending wire. The vegetative canopy originate from the buds of the vine shoot.
It reach maximum efficiency when the shoots are well distributed along the row and the leaves intercept the light well. On the contrary with bundling between the shoots there is poor light interception and bunches of clusters are created. This increase the risk of phytosanitary problems on the clusters.
MODIFIED FORMS OF GUYOT
Mainly adopted in the varieties with basal gems sterility or long internodes. Elongating the head will allow for using a higher number of buds and the distance between the two wires will allow for a constant curvature along the entire length of the shoot/branch thus reducing acrotony. The distance between the two wires must be carefully calculated because if too wide, the median section of the head will be emptied. It can be single or double depending on the number of bent shoots.
Simple or double, the “Pergola” is one of few systems that provides the ramification. The head splits in 2 or 3 branches and every branch has a spur and a shoot on the top. The vegetative canopy develops on the support structure which, depending on the viticultural tradition of the region it belongs to, can be parallel to the ground or inclined. It allows to reach remarkable productions in function of the load of buds/hectare. To keep high quality level, the clusters must be reduced with a green harvest.
In the “Pistolette” method the head cannot be bent as the vegetative point has grown higher than the wire. Any bending action would concentrate the leaf wall near the trunk thus creating bundles of vegetation and grapes. This method is suitable for plants with a low growth-rate and with high Gross Saleable Production.