American Vineyard Foundation California Competitive Grant Program for Research in Viticulture and Enology Viticulture Consortium Program Annual Progress Report January 2001 Project Title: Wine Grape Trellising and Vine Spacing Studies Principal Investigators: Nick Dokoozlian* Department of Viticulture and Enology UC Kearney Agricultural Center 9240 South Riverbend Avenue Parlier, CA 93648 Phone: 559/646-6587 Fax: 559/646-6593 E-mail: [email protected] Paul Verdegaal University of California Cooperative Extension - San Joaquin County Steven Vasquez University of California Cooperative Extension - Fresno County *PI to whom correspondence should be directed SUMMARY Three separate studies were conducted in 2000 to examine the effects of trellis/training system and in-row spacing on the yield, growth and fruit composition of wine grapes in the San Joaquin Valley. This progress report summarizes data collected during the second year of evaluation. In the first experiment, Chardonnay grapevines (Clone 4 grafted to 5C rootstock) were trained to six different systems trellis/training systems (Sprawl, VSP, Wye, Lyre, Smart-Henry and Smart- Dyson) at the Kearney Agricultural Center in Parlier. The horizontally divided Wye and Lyre systems produced the most clusters per vine, the Sprawl was intermediate, while the VSP, Smart- Dyson and Smart-Henry produced the fewest. However, when fruitfulness was expressed per foot cordon length, vines trellised to the Sprawl, VSP and Smart-Dyson were more fruitful than the remaining systems. Total yield per vine was generally similar among the trellising treatments, except that vines trained to the Lyre and Wye produced significantly greater yields than VSP vines. Based on standard industry row spacing for each treatment, estimated yields per acre ranged from 12.4 tons per acre for the Smart-Henry to 10.5 tons per acre for the California Sprawl. Sprawl and Smart-Dyson vines produced larger berries than the other treatments, while soluble solids, titratable acidity and juice pH were similar. Sprawl vines produced the greatest pruning weights per vine and per foot cordon length, the greatest mean cane weight, and the lowest yield:pruning weight ratio in the trial. In contrast, Wye and Smart-Henry vines had the lowest pruning weights per vine and per foot cordon length, as well as the greatest yield:pruning weight ratios in the trial. A separate experiment at the Kearney Agricultural Center examined the effects of in-row spacing and training system on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 4, 6, 8, 10 or 12 feet between vines in the row and trained to two training systems (bilateral vs. quadrilateral cordon). Nearly all bilateral cordon trained vines were trained fully in 1999, while the portion of fully trained quadrilateral cordon vines dropped linearly as in-row spacing increased. About 80% of the cordon wire was filled when quadrilateral vines were spaced 4 feet in the row, but this dropped to less than 40% when in-row spacing was 12 feet. Cordon and trunk diameters revealed that 4 and 6 foot in-row spacing reduced initial vine size compared to wider spacing, while canopy density (leaf layer number or LLN) also decreased as in-row spacing increased. Productivity per acre was maximized when in-row spacing was 6 to 8 feet for bilateral cordon vines. Maximum productivity per acre for quadrilateral vines was obtained with an in-row spacing of 4 feet, and tons per acre declined steadily as in-row spacing increased. No significant differences in berry size and fruit composition were observed among the treatments at harvest A trial was also established near Lodi in a commercial vineyard to examine the effects of in-row spacing on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 5, 7, 9, 11 or 13 feet apart in the row. Clusters per vine and total yield increased linearly with in-row spacing, while both parameters declined with increased in-row spacing when expressed per foot row or cordon length. Point quadrant parameters indicated that canopy density declined as in-row spacing increased. Total tons per acre were greatest when the space between vines ranged between 7 and 9 feet. No significant differences in berry size or fruit composition were observed among the treatments at harvest. Wines from all three trials will be evaluated in the spring of 2001. OBJECTIVES 1. Compare the yield, fruit quality and canopy characteristics of Chardonnay grapevines grown under six modern wine grape trellis/training systems commonly used in California. 2. Determine the effects of in-row spacing and training system on the yield, fruit quality and canopy characteristics of Syrah grapevines. EXPERIMENTS CONDUCTED Vineyard Sites, Treatments and Experimental Designs Trellis Study The trial is located at the Kearney Agricultural Center in Parlier, CA. Chardonnay grapevines (UC Clone 4) grafted to '5C' rootstock were planted in 1996 on sandy loam soil and oriented in east-west rows. The vines were trained to six different systems (Sprawl, VSP, Wye, Lyre, Smart-Henry and Smart-Dyson) in 1997 and 1998. Each system was replicated six times using seven vine plots arranged in a randomized complete block design. The middle three vines in each plot is used for data collection. All vines are spur pruned and cordon trained (bilateral and quadrilateral cordons for single curtains, quadrilateral cordons for double curtains). In-row vine spacing is 6' in all treatments, while between row spacing is 10'. All treatments were pruned to approximately 2, 2-3 bud spurs per foot cordon length, with 16 and 32 spurs retained per vine, respectively, on the single (Sprawl, VSP, Smart-Dyson) and divided (Wye, Lyre, Smart-Henry) curtain systems. Shoot positioning and hedging will be performed per standard industry practice for each system. Trellis dimensions and wiring configurations are shown in Figure 1. Syrah Spacing Studies Parlier Experiment - the trial is located at the Kearney Agricultural Center in Parlier, CA. Syrah grapevines (UC Clone 7) grafted to 5C rootstock were planted in 1997 on sandy loam soil and oriented in east-west rows. The experiment was designed as a 5 x 2 factorial consisting of in- row spacing (4, 6, 8, 10 or 12 feet between vines within the row) and training system (bilateral vs. quadrilateral cordon) arranged in a randomized complete block, split plot design. Each treatment is replicated six times using six vine plots. The middle two vines in each replication are used for data collection. The cordon height of both training treatments is 54". A single catch wire was placed 12" above the cordon on bilateral cordon trained vines. Fruiting curtains of the quadrilateral cordon vines are separated 22". A 30" crossarm, with 2 foliage support wires, was placed 12" above the cordons in this treatment. All treatments are pruned to approximately 2, 2- 3 bud spurs per foot cordon length. Between-row spacing is 11' for all treatments. Lodi Experiment - the trial is located in a commercial vineyard near Lodi, CA. Syrah grapevines (UC Clone 7) grafted to 5C rootstock were planted in 1997 on clay loam soil and oriented in east-west rows. The experiment was designed as a 5 x 3 factorial to analyze the effects of in-row spacing (5, 7, 9, 11 or 13 feet between vines within the row) and pruning level (5, 10 or 15 buds retained per pound dormant pruning weight). Data collection on the pruning level portion of the experiment will be initiated in 2001. The 10 bud per pound pruning weight treatment approximates the industry standard pruning level (approximately 2, 2-bud spurs per foot cordon length). The treatments are arranged in a randomized complete block, split plot design. Each spacing treatment (main plot) is replicated six times using 10 vine plots. Subplots (pruning treatments) are replicated 6 times using 2 vine plots. All vines are cordon trained, spur pruned and trellised to the vertically shoot positioned (VSP) system. Between-row spacing is 8' for all treatments. Light and Canopy Density Measurements The light environment along a vertical profile of the fruit zone in each replicate was determined with a sunfleck ceptometer (Decagon Devices, Inc, Pullman, WA) calibrated to measure average PPF. Measurements were taken near harvest between 11:00 and 13:00 Pacific Daylight Time (PDT). Point quadrant measurements were performed on data vines simultaneously to PPF measurements. The sharpened tip of a 1-m rod (3-mm diameter) was positioned perpendicularly to the canopy surface at the height of the fruit zone. The rod was inserted into the canopy at an angle of 90º with respect to the canopy exterior, and the number of leaves, clusters and gaps intercepted by the tip of the rod recorded. Readings were taken through the entire width of the canopy. Twenty insertions per replicate were made at 5-cm intervals. Leaf layer number was calculated as the mean number of leaf contacts per insertion. Vine Performance Evaluations Vine yield components (shoots/vine, clusters/shoot, berries/cluster, berry weight and total fresh weight, bunch rot incidence) were determined in each experiment. One-hundred berries were collected per replicate at harvest to determine berry weight, soluble solids, titratable acidity, juice pH, and skin anthocyanins (Syrah only). Yield components and fruit composition from upward and downward positioned shoots in the Smart Henry and Smart Dyson systems were recorded separately (Chardonnay only). Pruning weights, shoot numbers per vine and individual shoot weights were determined in each plot at dormancy. Fruit ripening was monitored in all experiments to allow treatments to be harvested at similar soluble solids levels (23.5 to 24.5 oBrix). Combined wine lots (250 pounds of fruit per treatment) from each trellis treatment in the Chardonnay experiment, as well as from main plot treatments in each Syrah experiment, were made and evaluated at the University of California, Davis Experimental Winery.