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Home , Canopy (grape), Veraison

Trellis Selection and Management

ver the past two decades, advance- As a result, a wide range of plant densities ments in design, trellis and training/trellis systems are routinely Oand training systems, and canopy employed in California produc- management practices have dramatically tion. The trellises used range from single to improved wine grape productivity and fruit divided curtain systems and employ both quality in California. Prior to this period, horizontal and vertical canopy division. a standard vineyard design and trellis sys- Due to both cost and durability, metal has tem was used throughout the state. Little replaced wood as the material of preference attention was paid to site-specific factors for trellis construction. influencing vine vigor such as climate, grow- The major wine grape trellis systems cur- ing region, soil type, and . Now rently used in California are outlined in the significant effort is made to match vineyard following table. A primary consideration design and trellis system to the site-specific when selecting the proper trellis system is factors that influence potential vine growth. anticipated vine vigor or canopy size. Highly

SINGLE CURTAIN SYSTEMS Region Application Two-wire vertical trellis (also called Simple Curtain or California Sprawl) Used in the Used when antici- San Joaquin pated vine vigor is foliage Valley as moderate to high support wire well as some cordon wire 12" areas of the Central Coast

54"

Vertical--positioned trellis (VSP) Used in Used when antici- coastal pated vine vigor is movable shoot regions moderate to low wires (3 pairs) and in the 14" northern San Joaquin 12" Valley

cordon wire 10"

32"

16 Wine Grape Varieties in California vigorous vines require larger, more expansive ence vine growth. Deep, fertile soils with large trellising systems than low-vigor vines. Before amounts of stored soil moisture support vigor- vineyard establishment it is important to accu- ous vine growth, while soils of moderate rooting rately estimate anticipated vine vigor or canopy depth and lower amounts of stored sup- size to select the proper trellis system. port less growth. Lastly, pre-plant soil prepara- Climate plays a major role in determining tion (ripping or slip plowing), cultivar, rootstock vine growth potential, particularly temperature, selection, and anticipated cultural practices (irri- annual rainfall, sunlight exposure, and wind gation, fertilization, and vineyard floor manage- velocity. Warm summer temperatures and large ment) also impact vine growth. amounts of sunlight exposure encourage large Other factors influencing trellis choice include canopies, while cooler temperatures or constant plant and row spacing, row orientation, estab- and high-velocity winds in the spring and sum- lishment costs, equipment requirements, and mer result in less-vigorous growth. Soil texture the desire to mechanize labor-intensive practices and potential vine-rooting depth also influ- such as and harvesting.

Training and Approximate pruning systems Spacing Mechanization cost Comments

Bilateral cordon training and Spacing ; pruning $1,500 per acre Most common system for wine spur pruning between vines or pre-pruning; for materials, trellis, grape production in San Joaquin is generally removal; hedging and installation Valley due to low establishment 6 to 8 feet. cost and ease of pruning and Spacing harvest mechanization. Canopy between rows configuration prevents excessive is 10 to fruit sunlight exposure in warm 12 feet. climates. Interior canopy shading can be a problem if vines are highly vigorous.

Bilateral cordon training and Spacing Harvest; pre-pruning; $2,500 per acre Most common trellis system for spur pruning most common. between vines shoot positioning; for materials, trellis, wine grape production in coastal Unilateral cordon training and is 3 to 8 feet. leaf removal; hedging and installation regions. Allows reduced between- spur pruning used when in- Spacing row spacing and increasing vine- row vine spacing is 5 feet or between rows yard design efficiency; requires less. Head training and cane is between shoot positioning. pruning used for some culti- 7 and 8 feet. vars in cool regions.

TRELLIS SELECTION 17 In addition to proper trellis selection, canopy formed in all trellised to the lyre, verti- management practices such as basal leaf removal, cal-shoot-positioned, Scott Henry, Smart-Henry, shoot positioning, and hedging are an integral and Smart-Dyson systems. Some form of hedg- part of high-quality wine grape production. Some ing or shoot trimming is necessary with most of form of basal leaf removal is practiced in the these systems as well. majority of coastal wine grape vineyards, as well Basal leaf removal consists of removing pri- as in many vineyards in the northern and central mary and lateral that subtend the San Joaquin Valley. Shoot positioning is per- four to six basal nodes on each primary shoot. In

SINGLE CURTAIN SYSTEM WITH VERTICALLY DIVIDED FOLIAGE Region Application Smart-Dyson Used in Used when antici- coastal pated vine vigor is upward shoot positioning wires (2 pairs) regions and moderate to high the northern 14" San Joaquin Valley cordon wire 13"

15" downward shoot positioning wires 30" (1 pair)

VERTICALLY DIVIDED DOUBLE CURTAIN Smart-Henry Used in Used when antici- coastal pated vine vigor is upward shoot positioning regions moderate to high wires (2 pairs)

14"

cordon wires 13" 9"

downward shoot 15" positioning wires (1 pair) 18"

VERTICALLY DIVIDED DOUBLE CURTAIN Scott Henry Used in Used when antici- coastal pated vine vigor is upward shoot positioning regions moderate to high wires (2 pairs) 14"

cane wires 13" 9"

downward shoot 15" positioning wires (1 pair) 18"

18 Wine Grape Varieties in California most regions leaves are removed on the shaded ing leaves immediately before softening, side of the row only (that is, the north side or , as fruit grown in the canopy shade of east-west-oriented rows or the east side of is highly susceptible to sunburn if suddenly north-south-oriented rows). Normally leaves are exposed at this time. removed shortly after berry set to allow clusters In many coastal vineyards, shoots are thinned to acclimate to increased sunlight exposure and in the early spring to reduce shoot congestion higher temperatures and to reduce the likeli- and crop load. Sterile shoots, and in some cases hood of sunburn. Growers should avoid remov- cluster-bearing shoots from non-count nodes, are

Training and Approximate pruning systems Spacing Mechanization cost Comments

Bilateral cordon training and Spacing Harvest; pre-pruning; $2,500 per acre Used for new vineyards or as spur pruning between vines leaf removal; hedging for materials, trellis, a retrofit for existing vineyards is generally and installation. trellised to VSP. Generally used in 6 to 8 feet. coastal regions when anticipated Spacing vine vigor is too high for VSP but between rows narrow-row spacing is desirable. is 7 to 8 feet. Between-row spacing should not be less than 7 feet in order to prevent shading of lower portion of canopy. Requires both upward and downward shoot positioning. Popularity increasing.

Bilateral cordon training and Spacing Harvest; pre-pruning; $2,500 per acre Used in coastal regions when spur pruning between vines leaf removal; hedging for materials, trellis, anticipated vine vigor is too high is 6 to 8 feet. and installation. for VSP but narrow row spac- Spacing ing is desirable. Requires that between rows bilateral cordon–trained vines is 7 to 8 feet. be alternated at two heights to create upper and lower fruiting zones. Lower fruiting zone often becomes weak over time.

Head training and cane Spacing Harvest; leaf removal; $2,500 per acre Similar application as Smart- pruning between vines hedging for materials, trellis, Dyson, except that cane prun- is 6 to 8 feet. and installation. ing allows easier separation of Spacing canopy. Used when cane pruning, between rows VSP canopy configuration, and is 7 to 8 feet. narrow-row spacing are desired under moderate- to high-vigor conditions.

TRELLIS SELECTION 19 removed when the average shoot length is 6 to vineyards where the row middle or area between 8 inches. Shoot thinning increases light reaching the fruiting zones becomes shaded following fruit the basal in the canopy interior. However, set. The vine foliage is separated or positioned under moderate- to high-vigor conditions the using movable wires. On vertically divided sys- effects of this practice on canopy tems, shoot positioning is performed several may be temporary due to compensating lateral times per year, typically near bloom and follow- shoot growth. ing berry set. For horizontally divided systems, In vertical-shoot-positioned (VSP) canopies, shoot positioning is normally performed once shoot positioning maintains canopy form and per year near bloom. foliage separation in narrow-row spacings. On Hedging or shoot trimming maintains canopy horizontally divided canopies (GDC or Wye), shape, prevents shading, and facilitates culti- shoot postioning maintains canopy separation. It vation and mechanization. The shoots of VSP improves light penetration to the canopy interior, canopies are trimmed when the foliage begins to particularly in vigorous, horizontally divided grow over the positioning wires at the top of the

HORIZONTALLY DIVIDED DOUBLE CURTAIN Region Application Double curtain (also called GDC type or Wye trellis) Used in Used when antici- coastal pated vine vigor is cordon wires regions and moderate to high the San Joaquin Valley

42"

54"

Lyre trellis Used pri- Used when antici- marily in the pated vine vigor is shoot positioning North Coast moderate to high wires (3 pairs)

cordon wire

58"

12"

12" ° 105 11"

40" 32"

20 Wine Grape Varieties in California canopy, usually sometime between berry set and veraison. The shoots are typically trimmed 6 to 8 inches above the top canopy wires. If signifi- cant lateral shoot growth has occurred, sides of the canopy are also hedged to maintain canopy width of approximately 18 to 20 inches. California Sprawl (two-wire vertical) canopies in the San Joaquin Valley are typically trimmed approximately 24 inches above the vineyard floor sometime near veraison. This facilitates air movement and decreases humidity in the fruiting zone. —Nick K. Dokoozlian

Training and Approximate pruning systems Spacing Mechanization cost Comments

Quadrilateral cordon training Spacing May be mechanically $2,000 per acre Used to reduce canopy density and spur pruning; divided cur- between vines harvested if curtains for materials, trellis, under high-vigor conditions. tain may also be formed using is 6 to 8 feet. are no more than and installation. Shoot positioning used in some bilateral cordon trained vines Spacing 30” apart. Pruning or cases to increase sunlight pen- that alternate from side to side between rows pre-pruning, hedging etration to the center of the (e.g., GDC). Distance between is 11 to may also be mecha- canopy. Overcropping may be a curtains ranges from 2 to 4 12 feet. nized. problem with highly fruitful or feet, depending on desire to large clustered cultivars. mechanize harvest.

Quadrilateral training Spacing Pre-pruning; leaf $3,500 per acre Found primarily in the North and spur pruning; distance between vines removal; hedging for materials, trellis, Coast in moderate- to high-vigor between curtains is 3 to is 6 to 8 feet. and installation. and 4 feet. Spacing vineyards. Not widely used due between rows to high establishment and annual is 10 to production costs. 12 feet.

TRELLIS SELECTION 21