Wine Grape Trellising and Vine Spacing Studies
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.