During the past two decades, advancements in vineyard design, trellis and training systems, and canopy management practices have dramatically improved wine grape productivity and fruit quality around the world. Prior to this, it was left to tradition and little attention was given to site-specific factors influencing vine vigour such as climate, growing region, soil type, and rootstock. Today significant effort is made to match vineyard design and trellis system to the site-specific factors that influence grape quality.
Vertical Shoot Positioned trellising (usually abbreviated as VSP) is designed to arrange shoots to grow upwards across guide wires. Usually four fruiting canes are trained to grow in opposite directions along two levels of wire. Fruit hangs approx 1m off the ground, and below the raft of vertically growing leaves.
The system is traditionally used where there is a high risk of fungus as the trellis keeps the foliage away from the ground and allows for good air circulation and light exposure. VSP offers many advantages over other trellis systems, including that it can be used with machine harvesters, all the fruit is grown in one zone, and it suits many grape varieties.
VSP is very common in cool climate regions, with low to moderate vigorous growth, as it encourages better air flow through the vine. This is accomplished by keeping all the shoots growing vertically, with no vegetative growth below the canes. The increase in air flow helps prevent problems associated with disease, allowing the fruiting area to dry out quicker after rains. With proper canopy management, the fruit is healthier, but being exposed to the sun earlier in the season, encouraging grapes to ripen more evenly within the bunch.
The objective of VSP is to train the shoots in a vertical fashion, creating a narrow layer that provides good exposure to sunlight and air flow in the fruiting zone of the canopy. The shoots length can easily be controlled by careful pruning any vegetation over the top catch wire.