Vineyard Trellis Systems
Training systems in use in today are categorized as having either non-divided or divided canopies. Nondivided canopy trellis systems have a “single fruit zone” and are less expensive to establish and maintain than divided canopy systems. Divided fruit zone (or divided canopy) trellis systems all have two fruit zones. The purpose of divided canopy systems is to expose more of the vine’s foliage to sunlight resulting in greater fruit production while still maintaining good fruit quality. Divided canopy systems are better suited to high-vigor varieties/rootstocks that require considerable annual effort to maintain a suitable canopy microclimate. Divided canopies are inappropriate in low-nutrient soils and areas where rainfall or irrigation is limited. Divided canopy systems can be horizontally or vertically divided, though the horizontally divided trellis systems are by far the most common. Geneva Double Curtain and Lyre systems are examples of canopies divided horizontally and the Scott Henry system and the related Smart-Dyson system are examples of vertically divided canopy systems. Horizontally divided canopies usually require wider row spacing than vertically divided canopy systems. The complex trellis required for divided-canopy system is elaborate and expensive to establish, but is usually results in increased yield and improved fruit quality.
Non-divided Canopy Systems
Umbrella Kniffin – Head-Trained Vines
Two- or three-wire trellises are used for umbrella kniffin trellis system (See Figure 8.4). A trunk extends to a point 4 to 6 inches (10 to 15 cm) below the top wire. This system utilizes long canes (10 to 20 buds each) that originate from renewal spurs at or near the top of the trunk.
High Bilateral Cordon
The high bilateral cordon system involves training the cordons along the top wire of the trellis (See Figure 8.5) in a manner similar to the low bilateral cordon system. The cordons remain as semi-permanent extensions of the trunk though they may need replacement every five or so years. Generally only two wires are needed for the trellis. The bottom wire serves as a training wire and a hanging wire for the irrigation system.
Vertical Shoot Position (VSP)
The vertical shoot position (VSP) system (See Figure 8.6), also known as the mid-wire cordon, restricts the fruiting/renewal zone to a small vertical zone along a single trellis wire. VSP is a good canopy management system for low to moderate vigor vines. It is very common in cool-climate viticultural regions of the world where it is used to invigorate shoots and ensure that buds and fruit are adequately exposed to sunlight. If the VSP system is used for high vigor vines, the canopy may be too dense, and leaf removal may be required to improve bunch exposure and reduce disease incidence.
Divided Canopy Systems
Geneva Double Curtain
The Geneva double curtain (GDC) system divides the canopy horizontally into two parallel hanging curtains with the fruiting zone positioned at the top of the canopy. The system is normally cordon-trained, spur-pruned to enable a greater bud count on high-capacity vines. It requires a three-wire trellis, using two horizontal cordon-support wires attached to the ends of a 4 foot (1.2 m) cross-arm at or near the top of the trellis post and a lower single trunk support wire.
Lyre, or U-Shaped, Training
The Lyre or U-shaped system (See Figure 8.8) is a horizontally divided trellis system adapted to upright growing varieties for medium to high yield vineyards. The Lyre system consists of a short trunk branching into bilateral cordons that diverge laterally, and then bend along parallel cordon wires. The bearing wood consists of equidistantly positioned spurs.
The Scott Henry system (See Figure 8.9) was designed to improve grape yields and quality in a high-capacity, cool climate site. The basic strategy of Scott Henry training is vertical canopy division with shoots being trained upward (phototropically) and downward (geotropically). Canopy division allows the use of a relatively large number of shoots per vine to achieve vine balance. Similar application as Smart-Dyson, except that cane pruning allows easier separation of canopy.
The Smart-Dyson system (See Figure 8.10) is similar to the Scott Henry system where curtains are vertically divided but instead shoots originate from the same cordon or fruiting zone. Unlike the Scott Henry system, the Smart-Dyson is cordon pruned.
Click on the following topics for more information on trellising grapevines.