Trellis

The trellis is the region's most ancient system of continuous and low guidance, with some examples of that type of plantation from the last hundred years. This system is formed by a row of 1.5-2 meters high trellis posts, with a 6-8 meters spacing and supporting 4-6 wires. The vines are usually planted with a close spacing (at intervals of about 1 meter) and flattened, allowing the grapes to grow at the first wire's height, namely very close to the ground.

This guiding system, in which the vine lines are around 3 meters apart, allows a mechanised and simplified vine treatment. The main disadvantage is the great pruning this system requires, causing vegetative and productive unbalances. In fact, these vines have a very small longevity and irregular productions.

Cross

The cross is a guiding system used in continuous vineyards, developed in the region and popular since the 70ties. Originally it was formed by a 2 meters high vertical post and a 1.5-2 meters long horizontal post, this one positioned 1.5-2.5 meters from the ground. The ends of the cross's arms, 5-8 meters away from each other, are linked by a wire. Four vines are planted next to each cross, following, in pairs, the cross's arms and then each one in its own wire.

Those vines are then pruned so that the leaves and the fruits develop only in the part where the plant is supported by the wire, forming two long parallel strings. This basic shape has suffered some changes, namely:

• the use of a third wire, linking the top of the cross and serving as support to two other vines that follow the vertical post; and
• the use of the vine supporting system, but combined with different ways of plantation (positioned two by two or isolated and planted on the alignment of the vertical posts, or directly under the wires).

The criticism made to this guiding system refers, from the technical point of view, to the plantation and to the difficulty in treating theses vines.

So it has been often verified that the death of a vine frequently gives origin to the death of all those planted in the same hole and whose roots developed in close connection with each other. On the other hand, the cross's spraying require particular care, as the "inside" of the plant is badly exposed to mechanised treatments. Furthermore, the existence of just one wire and vines exposed side by side favours the interlacing of the plants, giving origin to shades that are disadvantageous to maturation and increases the risk of cryptogamic diseases development.

From an economic point of view, the vine disposed in crosses takes around 8 years to reach a perfect production.

String

The string is another vine guiding system developed in the region and lately in expansion, being considered as the crosses evolution, as the type of guiding is similar, although in what concerns the supporting structures, it may be compared to the old trellis. Just like the trellis, the supporting structure is formed by trellis posts with a 6-8 meters spacing and 2.5-3 meters apart from each other, supporting 1.2 meters high wires.

The main objective is to make the vine reach those wires without ramification, allowing the vegetative and productive area to develop above the wires, similarly to what happens with the crosses.

One may opt for a simple string with just one supporting wire (about 1.5 from the ground) and one or two thinner wires to allow the vegetative development to hold itself, improving the leaves and specially the cluster's exposition; or for a overlaid string with two supporting wires (the first one slightly lower than the one of the simple string; the second one at a similar height to the one of the crosses) and another one supporting the vine's vegetative development, as it happens in the upper wire.

The string system seems to be the one that, from a technical point of view, raises less problems, as the treatments are easy to do, the chances of radicular contamination of the sick vines are low and the exposition and aeration are reasonably good. However, the double or overlaid strings may be accused of causing too much shade to the vine in the lower wire and, sometimes, of requiring that the pruning and the picking of the upper vine are made with the help of a ladder or the tractor trailer.

From an economic point of view, the perfect production of a vine in simple string guidance shall happen in the fourth year and it should not exceed 18 casks per hectare. Regarding the vines in overlaid strings, the perfect production of 20 casks per hectare will happen in the sixth production year.