Lyre / U-System Trellis (High Vigor Soils)

The Lyre or U-system trellis is a horizontally divided canopy system in which a single trunk branches into two bilateral cordons that diverge laterally, then run along parallel cordon wires spaced approximately 1 meter apart horizontally. Shoots are managed by vertical shoot-positioning, angling outward at roughly 10 to 15 degrees from vertical on each side, creating two distinct canopy walls. The end-on silhouette of the trained vine resembles the shape of the lyre instrument, which gives the system its name. Support posts form a V-shaped configuration, and the trellis infrastructure is more elaborate and expensive to install than single-curtain systems.

• Trunk branches into two cordons that diverge outward, each carrying equidistantly spaced spurs as bearing wood
• Parallel cordon wires are spaced approximately 1 meter apart in the horizontal plane and positioned approximately 1 meter high
• Shoots on each wall are vertically positioned, angling slightly outward to keep the two canopies open and separate
• End posts are set in a V-shaped configuration to support the diverging canopy geometry; the system requires more wire and structural material than VSP

On high-vigor sites, dense overlapping canopies shade the fruit zone, reduce photosynthetic efficiency, and promote fungal disease. The Lyre counters this by physically separating shoots into two independent curtains, each receiving its own light exposure and air movement. Horizontally divided systems like the Lyre expose more of the vine's total foliage to sunlight, which supports greater fruit production while maintaining fruit quality. Each canopy wall can also be managed somewhat independently, allowing targeted leaf removal or shoot thinning depending on the orientation and microclimate of each side.

• Distributes shoot density across two separate surfaces, reducing competition for light between individual shoots
• Improved air circulation between and around the two canopy walls reduces surface wetness and lowers pressure from fungal diseases such as botrytis and powdery mildew
• Training vines upward, as opposed to the downward-trained Geneva Double Curtain, keeps fruit under the canopy and reduces the risk of sunburn in warm conditions
• Divided canopy systems are better suited to high-vigor varieties and rootstocks that require considerable annual effort to maintain a suitable canopy microclimate in single-curtain systems

The core benefit of the Lyre on vigorous sites is improved and more consistent light exposure across the fruit zone. Research by Carbonneau and others demonstrated that training systems directly affect vine microclimate variables including cluster exposure, photosynthetic rates, and fruit composition, and that with the right system, yield can be increased alongside improvements in fruit composition and wine sensory quality. White wines produced from Lyre-trained vines on fertile sites tend to show improved aromatic definition because light-driven volatile development in the berry is more consistent. Red varieties benefit from more even phenolic maturation, reducing the green or herbaceous character that can emerge when fruit is heavily shaded.

• Consistent light penetration into the fruit zone supports more uniform sugar accumulation and aromatic development across clusters
• Reduced canopy density lowers botrytis and mildew incidence, which helps preserve aromatic freshness and reduces oxidative fault risk
• Both white and red varieties show improved fruit composition on high-vigor sites when managed in divided canopy systems versus overcrowded single-curtain training
• The system accommodates the natural productivity of fertile soils without forcing the vine into imbalance between vegetative and reproductive growth

The Lyre system is designed specifically for medium to high-capacity sites where vine vigor is driven by deep, fertile, well-drained soils with strong nitrogen availability. On such sites, VSP systems become difficult to manage because foliage grows too dense, leaves become scrunched within the wire framework, and repeated hedging passes are required to maintain canopy shape. Divided canopy systems including the Lyre are not appropriate for low-nutrient soils or dryland sites where vigor is naturally controlled. They are also less suitable where cold injury to extensive cordon development is a risk. The decision to install a Lyre is most economically sound as part of a new planting rather than as a retrofit of an existing system.

• Most appropriate on deep, fertile, well-drained soils with high nitrogen availability that drive strong vegetative growth regardless of rootstock or pruning choices
• Not recommended for low-nutrient soils, shallow substrates, or sites where irrigation is limited, as divided canopies depend on sufficient vigor to fill both curtains
• Less suitable in cold climates where extensive cordon development is vulnerable to winter injury and requires frequent replacement
• Most cost-effective when planned into a new vineyard at establishment, as converting existing vertical trellises to a Lyre geometry typically requires full redevelopment of the block

The Lyre was developed in the Bordeaux region of France and established through INRA experimental vineyards. It has since been adopted in commercial vineyards across major wine regions worldwide, including France, and in New World regions such as California, Oregon, and Washington. In the 1990s, following widespread replanting in California after the AxR rootstock failures, the Lyre saw significant uptake in the Napa Valley and surrounding areas. Practitioners including King Estate in Oregon use the Lyre on specific high-vigor blocks, noting its effectiveness against mildew and its suitability for Pinot Gris and Gewurztraminer. The system is well regarded wherever upright-growing Vitis vinifera varieties are cultivated on productive soils.

• Developed and first researched in the Bordeaux region of France, with INRA experimental vineyard work confirming quality improvements across diverse commercial sites worldwide
• Saw significant adoption in California during the 1990s replanting era, with Napa Valley reported as one of the highest concentrations of Lyre installation globally at that time
• Used in Oregon at estates such as King Estate for Pinot Gris and Gewurztraminer on high-vigor blocks, valued for mildew defense and reduced sun exposure on white wine varieties
• Also suitable and documented in France, Germany, New Zealand, and South America, wherever upright Vitis vinifera varieties face vigor challenges on fertile soils

The Lyre requires more elaborate infrastructure than VSP or single-curtain systems, with V-configured end posts, two parallel cordon support wires, and additional shoot-positioning wires on each side. The complex trellis is expensive to establish but typically results in increased yield and improved fruit quality on sites where it is appropriate. The most significant ongoing trade-off is labor intensity: because the vine occupies both sides of a horizontal structure, every canopy operation requires more passes and handling time. Critically, most mechanical pruning, pre-pruning, and harvesting equipment is designed for vertical trellises and cannot be used directly on the Lyre geometry, making the system heavily dependent on skilled hand labor throughout the growing season.

• Trellis infrastructure is more complex and costly than VSP, requiring V-shaped end posts, paired cordon wires, and shoot-positioning wires on each canopy wall
• Divided canopy systems generally deliver increased yield and improved fruit quality on high-capacity sites, which can justify the higher establishment cost over the vineyard's productive life
• Horizontal structure makes standard mechanical pruning, pre-pruning, and harvesting equipment incompatible; most machines are built for vertical trellis configurations
• Both sides of the vine require individual attention during shoot thinning, leaf removal, and canopy work, making total annual labor per hectare higher than equivalent VSP management